CA2187756C - Disposable cassette with negative head height fluid supply and method - Google Patents

Abstract

A fluid infusion pump includes a disposable cassette (12) having an inlet (16), an outlet (24), and a fluid chamber (36) between the inlet and the outlet. There is a fixed wall (180) of the fluid chamber and a movable wall (182) of the fluid chamber. A pump body (26) receives the cassette in a fixed operating relationship such that an actuator (62) in the pump body is activatable for reciprocal advancement and retraction with respect to the cassette and is adapted to confront the movable diaphragm when the cassette is received in the pump body. There is a detachable coupling (44) between the actuator mounted in the pump body and the movable wall. The disposable cassette further includes an actuating means adapted to magnetically and detachably engage a magnetically attractable means attached to a movable wall of the disposable cassette and a relatively rigid carrier having concave indentations.

Description

2146610675 ROSS CLRPP KORN MONT T-89B P-005 MRY 08 ,'96 16:9 .~ _ ~~ai'~~ 95~/ p-. l Q
ip~'wlt~~ 0 8 ~IA~ 1996 KEND-23,773 DISPOSABLE CASSETTE 'WITH NEGATTVE HEAD HEIGHT
FLUID SUPPLY AND METHOD
TECHNICAL FIELD OF THE IN'~TENTION
This invention relates to the delivery of a fluid to a patient by s pressurizing the fluid, and in particular, to an infusion pump which provides fluid from a negative head pressure supply for delivery to a patient, which infusion pump incorporates an inexpensive disposable cassette.
~1MENOEO S~cw~' ~ia6610675 ROSS CLAPP KORN MONT T-898 P-006 MRY 08 '96 16:39 218 l ~ ~ f~ n~.vus o s SAY Toss BACKGROUND OF THE INVENTION
Infusion of fluids, such as drugs and plasma, into a patient is commonplace in the z~aedical field. Two common infusion, methods are intravenous delivery of fluids by gravity and either intravenous or infra-anerial s delivery by actually pumping the fluids for delivery to the patient.
In pump delivery, an infusion pump is used to pressurize the fluid.
Past devices often require a complac cassette mechanism which coxn~es into direct contact with the fluid to be delivered. Other devices require fluid to be fed by gravity to a pumping instrument having a cassette.
~o Peristaltic pumps acting upon in-line tubing segments have been used in this art. One example of a peristaltic pump, disclosed in U. S. Patent No.
4,155,362, includes a back pressure valve to prevent gravity siphoning from the pumping chamber.
Another relatively simple pumpiung arrangement is disclosed in U. S.
15 Patent No. 4,142,524, in. which a cassette is provided with W let and outlet valves to and from a pumping chamber_ The pump presses a rubber diaphragm on the cassette to diminish the volume of the cassette chamber by a known amount to deliver a predetermined quantity per pump stroke. An even simpler disposable element is disclosed in the pumping arrangement of U. S. Patent No. 4,199,307, 2o in which a pancake-shaped resilient pumping cb.amber is provided with upper and lower valves and an activating pumping piston which displaces a known volume on the pumping stroke. Yec another pump approach is dis~QSed in (~,T. $.
Patent No. 4,322,201, which seeks to provide continuous, uninterrupted fluid flow by alternating between two pumping chambers, each of which employs the principle 25 of the rolling diaphragm. A third rolling diaphragm chamber is employed for mechanically sensing pressure within the device for control purposes.
Another delivery pump system as disclosed in U_ S. Patent No.
4,657,490, employs a simple disposable element in combination with a relatively AMENJE~ -HAT~

"'14661e675 ROSS CLAPP KORN MONT T-89B P-007 MAY 0 '96 16:40 _. . PC~IUS 95/ 0~7~2 lPEA/US 0 8 ~l,c'~ i~96 straightforward gravity supply and positive pumping action which is acc,.~rate and which provides pressure monitoring and self-checki.ag diagnostics through measuring the pressure exerted on the pump actuator_ None of the foregoing art, however, provide a simple disposable element with a positive feed capable of drawing fluid from a negative head pressure supply in combination with simple straightforward delivery pumping action which is accurate and reliable and which provides improved reliability pressure monitoring through the cassette pumping 'membrane and self check diagnostics.
to SUI~wIARY OF THE INTENTION
One aspect of the present invention is a disposable cassette for use in medical infusion fluid pumping to positively draw fluid into the cassette for positive pumping to a patient. At least one pumping chamber in the cassette cooperates with a pumping instrument (in which it is operatively held to draw ~5 fluid from a negative pressure fluid source or a negative head height without relying on positive head height gravity feed. The cassexte is formed of one or two layers o~ flexible sheet material welded together and applied to a semi-rigid thin backing plate. Detachable connector means are provided in the area of the inlet chamber fot drawing in fluid, which connector means arc coupled to as actuator 2o in the pumping instrument to which the ca,ssrtte is inserted. The actuator a detachably coupled to the inlet chamber aad upon retraction draws one wall of the chamber away from the other wall, thereby creating a negative pressure within the chamber to draw fluid through the inlet into the chamber. The inlet is closed with a faxst valve means pressing the inlet closed and the actuator z5 advances against the chamber to decrease the volume of the chamber, forcing out ~l.uid for eventual infusion to the patient. The positive supply of fluid allows a reliable amount of fluid to be available for infusion to the patient whether or not a supply source is above or below the infusion pump. The valve by which fluid AMEN.'.7F~ ~,~''-~=

'146610675 ROSS CLRPP KORN MONT T-B98 P-008 MRY 08 '96 16:40 1 ~'' 7 ~' ~ 'a PC~'I~1~ 9 ~ l p 4 7 p 2 !P~/U~ C~ 8 MAY 1995 is wansferred out of the inlet ch~~mber is closed, the inlet valve is ..pened, and the inlet actuator is withdrawn, so that the inlet chamber walls are moved back creating an increased volume and therefore, a negative pressure is the inlet chamber. The inlet chamber fills with fluid and the cycle can be repeated.
When service to the patient is completed, or when the medicine is changed, the inlet actuator can be detached from the inlet chamber and the cassette can be removod and disposed while the relatively uxore complex pumping and mechanical valve system and instrument can be re-used without contamination. A new sterile cassette can be replaceably inserted and the inlet actuator can be coupled to the 1o inlet chamber for use with a new patient or wirh a new infusion solution_ Another feature of the invention is the use of a magnetic coupling between the islet chamber of the cassette sad the inlet pumping actuator. A
thin metal disk is attached to a flezible wall of the iaalet pumping chamber which corresponds in, location to a magnetic inlet actuator is the pumping instrusnent.
The magnrtic actuator secures itself to a fleuble wall through magnetic couplin.g_ The ocher wall of the inlet chamber of the disposable cassette is rigidified or otherwise ratraiaed from moving toward the flezible wall_ Tn the case of a single flexible sheet, the rigid carrier itself forms the rigidified wall. Tn the case of two flexible cassette construction, one of these flexible sheets is adhered to the rigid 2o carrier. This allows the inlet pumping actuator to draw the flexible wall.
outward, thereby increasing the volume within the pumping chamber and drawing fluid into the cassette.
In accordan=ce with another aspen of the present invention, a pumping chamber is provided in the disposable cassette which is distinct from the inlet ~s chamber. Fluid is drawn into the inlet chamber which acts as a reservoir supply chamber or a refill chamber and, is transferred from the i~olet chamber into the outlet pumping chamber and a pumped to a patient for infusion. The disposable cassette has a flexible will and a rigid wall defining the inlet and outlet chambers AMENOE~J S.:EET

?146610675 ROSS CLRPP KORN MONT T-898 P-009 MRY 08 '96 16:41 2~ ~1~'.~~ PC~t/~S 95/ p'~702 within the cassette; the irxlet pumping chamber being variable in volume by the retraction or advancement of an inlet actuator, the outlet pump chamber being variable in volutue as fluid fills the chamber or is pushed fiom it with an outlet actuator. The disposable cassette further has an inlet passage foz movement of 5 fluid into the inlet pump chamber, a transfer passage for moving fluid from the inlet pump chamber to the outlet pump chamber and as outlet passage for moving the fluid out of the outlet pump dxamber. Also, inlet and outlet valves ate provided for opening and closing the inlet and outlet, and a transfer valve is provided for opening and closing the transfer passage between the inlet pump lo chamber and the outlet pump chamber to control movement into the inlet pump chamber and from the inlet pump chauiber into the outlet pumvp chamber. A
carrier which is relatively rigid with respect to the flexible wall has an inlet concave depression, which forms a rigid wall spaced apart ~:rom the flexible wall of the cassette to form the inlet pumping chamber. Together, the flexible wall and the concave depression establish the inlet chamber volume_ The flexible layer is securely affixed around the perimeter edge of the inlet concave depression, such that it is deformable in both inward and outward directions. An inlet pumping actuator is provided for contacting and drtachably coupling with the outer surface of the deformable sheet to deform the sheet by either compression or expansion 2o between the deformable sheet and the inlet concave depression and to thereby decrease or increase the volume of the inlet pumping chamber and to draw fluid into the inlet pumping chamber or to expel fluid into the outlet pumping chamber.
An outlet concave depression is defined in the relatively rigid carrier such that the outlet pumping chamber conforms to the outlet concave depression, and is confined in its movement at least in the outward direction.
An outlet pumping actuator is provided for contacting the outer surface of the deformable sheet at the outlet pumping chamber to deform the AMENOF~ ~'-~~-~T

?146610675 ROSS CLRPP KORN MONT T-8!3B P-010 MRY 08 '96 16:41 Pcr~US 95i o~702 IPEA/US t~ ~ "~~~,'' a;
218~7.'~6 second sheet between the pumping member and the contming depression of the relatively rigid carrier to decrease the volume of the pump chamber and pump the fluid from the pumping chamber.
An outlet or delivery valve is provided for closing the outlet passage to a variable orifice size so that the valve mechanism gradually retracts to permit restricted fluid flow from the pump chamber past the outlet valve wh;~
movement of the outlet pumping actuator pressurizes the fluid in the pumping chamber to a predetermined pressure. The outlet valve can be electronically controlled to allow the pressuw in the pump chamber to be automatically 1o controlled in a predetermined manner, as by controlling it t:o a constant pressure level selected by the user. The semi-rigid carrier is provided with an orifice in the concave outlet depression, so that a sensor can measure the fluid pressure in the outlet pump chamber directly through a flexible membrane, such as another flexible sheet, and caa detect various condiraions, including potentially dangerous is conditions such as a lack of fluid, valve failure, and fluid obstructions.
In accordance with aaather aspect of the present invention, a carrier having concave depressions for both the inlet and outlet pumping chambers further includes concave passage depressions which are than the inlet passage, transfer passage, and outlet passage, as formed between the flexible sheet and the 2o rigid tastier. The coacave passage depressions correspond in locatioa to inlet, transfer and outlet valve mechanism, so that alignment ~f the passages with the closing valve mechanism results in positive closure.
Another feature of the invention is positive sealing in the valve areas of the passages, which results from a speta.fic structure produced by an improved 2s RF welding method. The unique structure results from welding a single flexible sheet compoxd of polyvinyl chloride (PVC) to a relatively thicker, rigid carrier compostd of a copolyester material. One aspect of the inventive RF welding method provides successful welding at the surface. The method includes ,4MENDED SHEET

'146618675 ROSS CLRPP KORN MONT T-898 P-011 MRY 08 '96 16:42 PCT/US 95 / p4702 '~,~ ~ r.~ w~ l._ , ~~i~a':~~;..;:~ i~~'~Y 1596 preheating RF die heads, so chat a die head contacting the thin PVC sheet is at a higher temperature than another die head conta~i.ag the P'VC sheer, adjusted so that the RF weld point occurs ai the interface between the PVC sheet and the copolyester carrier.
Another aspen of an inventive RF welding method eliminates the adverse consequences of weld extrusion into the transfer valve passage and into the restricci.on valve passage.
,a.MENDFD SH~E~' 146610675 8055 CLRPP KORN MONT T-8~8 P-012 MAY 08 '96 16:42 ~~~~ ~:~ 0 8 MAY .996 ~1~1756 BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the invention may be had by reference to the following detailed description and claims when taken in conjunction with the accompanying drawings, wherein like elements are s represented by like numerals and wherein:
Figure 1 is a schematic representation of as infusion pump forming one embodiment of the present invention;
Figure 2 is a perspective view of a disposable cassette according to one embodiment of the present invention;
to Figure 3 is a cross-sectional view of the infusion pump of Figure 1 taken along a horizontal plane through a center line of as installed disposable curette;
Figure 4 is a schematic front view of the pump prior to insertion of the disposable cassette according to the present invention;
15 Figtues 5, 6, and 7 illustrate schematically the operational sequence of an infusion pump according to one embodi,nneat of the present invention;
Figure 8 is a schematic diagxam of a microprocessor control circuit;
Figure 9 is a schematic process flow diagram of the method of construction according to the present invention;
zo Figure 10 is a perspective view schematically depicting the assembly coastrucrion of the cassette according to the present invention;
Figure 11 is a side cross-sectional view taken along line 15-15 of the cassette assembly of Figure 2;
Figure 12 is a schemuic assembly view of an alternative embodiment Zs of a coupling mechanism according co the present inventian;
Figure 13 is a perspective assembly view of an embodimem of the cassette formed with one sheet of flexible PVC to be welded directly to a rigid carrier to form a fluid passage therebetweett;
AMEt~O~~ S~~~T

?146610675 ROSS CLRPP KORN MONT T-898 P-013 MRY 08 '96 16:43 ~~TIUS 95/ 04702 i ~ 7 ;~ ~r~ IPE~'~~ 0 ~3 MAY 1996 Figure 14 is a top view of a single sheet cassette, according to one embodiment of the present invention;
Figure 15 is a bottom view of the cassette of Figure 14;
Figure 16 is a central cross-sectional view taken aloag a centerline 16-16 of Figure 14;
Figure 17 is a cross-section at 17-17 of Figure 14;
Figure 18 is a cross-section at 18-18 of Figure 14;
Figure 19 is a cross-section at 19-19 of Figure 16;
Figure 20 is a uoss-section at 2D-20 of Figure 1b;
Figure 21 is a cross-section at 21-21 of Figure 1~;
Figure 22 is an enlarged partial detail cross-sectional view of the inlet boss and orifice at 22 of Figure 16;
Figure 23 is a cross-sectional schematic depiction of an RF welding process and apparatus, according to one embodiment of the present invention;
1s Figure 24 a a cross-sectional schematic depiction of another part of an RF welding process and apparatus, according to one embodiment of the present invention;
Figure 25 is a cross-sectional schematic depiction of an alternative preferred RF welding process and apparatus, according to the present invention;
2o Figure 26 is a schematic graphical depiction of RF welding time, according to the process of Figure 25; and Figure 27 is a partial perspective view of an upper RF die and delrin insert, according to the method and apparatus of Figure 25.
AMEf'»~~7 c~:ar. v:

?146610675 ROSS CLRPP KORN MONT T-898 P-014 MRY 08 '96 16:43 ~ ~~7 '~~ PCTIUS 95 / ~~ 702 ~PEA/US 0 S ~~~:~Y i~~6 DETAILED DESCRIPTION OF THE PREFERRED EMBODnVIENTS
As illustrated in Figure 1, the pumping rystem is composed of a pumping instrument 10 in which a disposable cassette 12 is mouaated for operation. The supply container 14 containing the fluid to be infused may be s positioned above or below the cassette 12 and is connected to inlet 1b of cassette 12 by means of tubing 18. Outlet tubing 20 extends to th,e patient 22 from the outlet 24 of cassetxe 12.
At the front of the instrument body 10 is a cassette receiving and actuating section 26, including cassette positioning pins 28. A dosable door 30 is io pivotable about hinges 32 for rcplaceably holding the cassette 12 within the cassette receiving section 26 properly aligned as with alignment pins 28 for operational confiontativn between the cassette and the pumping instrument. A
data display/operator input patnel 34 may be formed on the front of instrument body 10 and preferably is formed on the front of closable door 30 for display of ~s operational data and for operator input while the cassette is held in place by closure of door 30. The details of the actuator receiver section will be more fully explained below with reference to Figures 3 and 4.
A preferred embodiment of the disposable cassette assembly 12 is shown in a top plan view in Figure 2. The cassette has an inlet chamber 36 which zo is in fluid comu~unication with inlet 16 through inlet passage 38. One wall 40 of inlet chamber 36 is flezible, and forms a flexible wall 40 having a.ff red thereto a portion 42 of a detachable coupling mechanism 44.
In the embodiment of the disposable cassette 12, shown in a perspective view in Figure 2, the portion 42 of the coupling mechanism 44 is a 2s magnetically attractable disk, such as a metal disk which is affixed to flexible wall 40. As will be more fully understood with reference to Figure 3, disk 42 couples with magnet 46 which is attached to inlet pumping actuator 62 and forms the second portion of detachable coupling mechanism 44. Fluid is received into inlet AMENDED SWEcT

chamber 3b through inlet passage 38 and is transferred out of inlet chamber 36 through transfer passage 48 and ousward from the cassette through outlet 2 4 PreFaably, the cass~e 12 also defines an outlet pumping chamber 50 which rxaives fluid through waasfer passage 48 and from which fluid is pumped through outlet passage 52 to outles 2 4 and is delivered by cube 20 to the patient.
As will be more fully explained below is coaaKdon with the construction of the c>.ssate assembly 12 as set forth in Figures 9 through 11, alignment holes 54 are formed for alignment during the coastrucxioa of the cassette asxaably and also for alignment doting iastal>ztioa of the cassette assembly within the cassette 1o receiving and actuation section 26 of the pumping inscniment 10.
The details of construction of the curette receiver aeiuator section 26 are best illustrated is Figures 3 and 4. Figure 3 is a cross-sectional view of pumping body 10 taken along a horizontal place Through the pumping instrument cad disposable cauette. Figure 4 is a front view of the cassette receiving section 26 of the puaup 10 prior to mounting the disposable cassette 12.
The moving members which confront cad act upon cassette 12 when ii is in as operating position are arrayed on panel 58 secured to the instrument body 10.
Proceeding from upstream, the major elements are inlet valve 60, inlet actuator 62, cr~uo,sfer valve 64, outlet pumping member 66, cad outlet valve 68.
2o The outlet pumping assembly 66 preferably indudss a central hub 70 surrounded by a plurality of petal-shaped sections 72 to form the movable Pressing surbce which produces pumping pressure is the outlet pumping chamber of the disposable cassette 1Z The hub 70 mry be formed by press fit of a malt hub member cad a female hub memker. A circular ~~YPe~ 74 near the voter a edge of hub 70 is formed between the male and female hub members_ Each petal section 72 is provided on the rear face of its inner end with a smooth hook-shaped curve portion 76 which corresponda to a smooth curve provided on the hub recess 7~. The inner edge of each petal section 72 is pivotally retained is the hub recess 74, with the complementary smooth curves of each me:.:ber permitting reliu~rc pivotal movement of each petal-shaped section With respect to the hub abous as azis pe:pendicular to ra;ess 74. The inatrumeas body paced 58 is provided with as annular recess that cinumferentially surrounds petal nest 78, which reaias the outer end of each getal shaped section 72. The coaf~coatiog surfaces of petal nest 78 aced the outer end of each petal-shaped section 72 are also shaped for smooth pivoting of the petal-shaped sections With respect to the instrument body. A movable carriage 84 is mounted behind hub 70 and carries a drive nut 86 Which is engaged With the threads of a threaded motor shaft 88 lo rotated by motor 90. The forward end of czniag~e 84 may be recessed to recEive a load cell 9 2 which has its central force measuring diaphragm confronting a metal ball 94 retained in a rear oeatral recess 96 formed on hub 70.
Preferably, however, a pressure sensor 91 is positioned and curled is door 30 for direct contact against the xcoad wall 93 of the outlet pumping chaiaber 50 of cassette 12_ The pressure sensor 91 will have improved pressure reading accuracy over a load cell 9 2 beaux of its substantially direct access to pressure chamber SO
without smsiag frictional variations due to variable sliding conditions of pumping acruuor 70 and associated movement of petals 72. Also, a more direct pump actuation may be aaoomplished with the doorL mounted pressure sensor 91, as the load odl 9 2 and associated metal ball 94 may be replaced With a continuous connector shaft 95 as schematically depicted in Figutes 5 through 7, from stepper motor 90_ Rotation of stepper motor 90 acts through the cooperauon of threaded motor shaft 88 and the carriagt nut 86 to drive carriage 84 forward_ 'his Zs acrioa uaasmirs force to hub 70 moving she hub forward.. The translauonal motion of hub 70 also causes each petal-shaped senior 72 lo pivot near each of its ends. The petal assembly thus forms a rsuncated cone of varying height as the 2146610675 ROSS CLRPP KORN MONT T-8'38 P-017 MHY 08 '96 16:45 PCTlUS 95/ 04702 ~PF~Is~~ 4 8 I~AY 1996 1877~~6 hub :roves between the extreme retracted position and advanced position, as depicted in Figures 5 and 6.
Inlet actuator 62 is carried forward by refill shaft 98 which is either advanced forwardly or retracted rearwardly through lever 100 acted upon by carriage 84. Thus, as viewed is Figure 3, when carriage 84 is moving forwardly to push the outlet pump assembly 66 forward, the action of refill lever 100 causes shaft 98 and inlet pump member 62 to be withdrawn, withdrawing metal disk 42 and inlet pump chamber diaphragm 40 with it. As molar 90 is driven in the opposite direction to withdraw carriage 84, lever 100 allows the inlet pumping 1o member 62 to move forward. Spring 102 biases member b2 to its forward position and thus carriage 84 to the rearward direction.
Inlet valve 60 and transfer valve 64 have rounded surfaces for engaging the flow path of the cassette 12 and are operated in tandtm fash,iora through inlet valve lever 104 driven by solenoid 106. When one of the two valves is in the open ~s or rearward position, the other is necessarily in the closed or forward position_ Preferably, the parts are assembled so that in the middle of the path of travel of valve lever 104, both valves 60 and 64 are closed to insure no bypassing of fluid.
Bias to inlet valve lever 104 is provided by spring 108 surrounding the inlet valve shat, which biases the arrangement to the condition of inlet valve 60 open, 2o transfer valve 64 dosed.
Outlet valve 68 is operated by a stepper motor 112 acting upon delivery lever 114 and is biased to the closed position by spring 116. The linear stepper motor 112 is capable of positioning the delivery restriction valve 68 in any selected position from fully retracted or open position as shown, to a fully z5 extended or dosed position. This permits the output from outlet pumping chamber to be metered according to the selected oprning position of the delivery restriction valve 68.
AMENDED SH~~T

46610675 ROSS CLRPP KDRN MONT T-89H P-018 MRY 08 '96 16:45 r~ ,~, ~ t,, ~ ~ ~'CTi U ~ , ! 9 ~ / 0 4 ~ ~ ,~
~_ 1 b . ~~L: v~.~~ ~ ~ I~AY 7996 As indicated previously, actuator panel 58 is provided with mounting pins 28 corresponding to the alignment in mounting holes 54 in cassette 12.
The actuator door 30 is mounted to panel 58 by hinges 32 and is dosed by latch 118.
As a double check for patient safrty, opening of door 30 will stop pumping and sound an alarm. In the inner face 110 of door 30, concave depression 120 is arranged to confront petal assembly 66 when the door is dosed, and simi:ar concave depression 122 confronts the refill actuator 62. Depressions 120 and may be provided with air vent holes through the front door to facilitate dosing the door with cassette 12 in position. With the cassette mounted on pins 28, the to inlet fluid chamber 36 and the outlet pump chamber 50 are captured between the inlet actuator 62 and outlet member 66 and the depressions 122 and 120, respectively. In the operating position, valve 60 is adjacent inlet passage 38 to dose off the inlet when the valve member 60 is e~cended. Likewise, valve 64 may be activated to dose off transfer passage 48_ z5 The delivery valve 68 may be activated to selectively close oudez passage 52 to an orifice of any desiued size. The pumping compartment defined between the rigid wall of depression 120 and the outlet pump petal assembly 66 is filled by the fluid from an inlet chamber 36 when the petal assembly 66 is in its retracted position, and the outlet pump dumber 50 is bulged with fluid at a low zo fluid pressure of approximately ten (10) inches of water. ',Che volumetricity of pumping is then provided by the accuracy of volume displaced between the extreme positions of outlet pump assembly b6 and the compliance of the exterior wall of outlet pump chamber 50 to the moving truncated cane surface presented by petal pump assembly 66.
z5 As will be discussed more fully below, the material used to construct the cassette is flexible, and therefore conforms to the surface of the petal elements so that the position of the petal assembly defines the volume of fluid endosed between it and the rigid surface on the other side very precisely. The volumetric ~4MEP,~DED SHEET

performance of this arrsagemeat is dtbaed almost completely by the movement of the hub 70 and thus, the petal-shaped sections 72 and not by the mechanical properties of the disposable casxtte element Which is confined from movement.
The volume displaced by the petal assembly varies is a Linear fashion with s triaslational movement of hub 70.
As illuss:-ued is Figure 8, the symm is operated under the coauol of a microprocessor system 124. The microprocessor controls the movement of solenoid 106 between two positions: (1) inlet valve open, uansfer valve dosed, and (2) inlet valve closed, transfer valve open. Likewise, microprocessor 124 to controls delivery vzlv~e stepper motor 112 to select the total or partial resmiction imposed by delivery vaW a 68 on the cassette outlet passage 52. Microprocessor 124 also xlecrs, in accordance wrath the rate selected by the operator on input panel 34, the rate of mrnrement of the pumping stepper motor 90. Continuous conuol ova operation, diagnostics and aberrant conditions are principally 15 provided by either a load cell 92, which measures the force being a=erred on pumping assembly 66, or by pressure sensor 91 which directly measures the pressure in the outles pump chamber 50, as eierted by petal assembly 66. As indicated prtviously, a door-mounted load cell 91 is preferred for a~.tau pressure measurement. This data is continuously provided to microprocessor x24 or trough analog to digital converter 126.
A' typical cycle of operation is illustrated is Figures 5 through 7.
Figure 5 illustrates the condition of the actuator and disposable cassette as the delivery portion of the cycle has begun. At this stage, the outlet pump chamber 50 has bees completely filled with fluid to occupy the cotnpartmeat formed ~5 bez.ve~a the cauecu nudes chamber depr~GUioa and the fully retractod petal assembly 66. Delivery valve 68 and transfer valve 64 are dosed, completely capturing the fluid is outlet pump chamber 50. Isles valve 60 is opened while the transfer valve b4 is dosed, so that fluid may be drawn into the inlet fluid chamber X146618675 ROSS CLAPP KORN MONT T-838 P-020 MAY 08 '96 16:47 PCT~US / 0 47 21 ~'r l ,~' ~ ~ ~PE~/U ~' ~~~
MAY 1~9~

36 as inlet actuator 62 is retracted. The microprocessor begins the initial stage of the delivery cycle by directing the outlet pump stepper motor 90 to advance to begin pressurization of fluid in outlet pump chamber 50. During the first few steps of stepper motor operation, valves 68 and 64 remain closed to permit this s initial pressurization. Elevation of the pressure caused by the advancement of petal assembly 66 is sensed by pressure sensor 91 which data is fed to microprocessor 124. This serves as a diagnostic step to verify the capturing of a full load of fluid in the outlet pump chamber S0. A :Failure to pressuri7x in the first several steps of motor 90 indicates a system problem. It could be that the to fluid supply is depleted, so that the outlet pump chamber ~>0 has not been filled, or that the inlet actuator mechanism has not appropriately filled inlet supply chamber 36. Another possibility is that a defect in valve b4 or 68 is permitting fluid to leak from chamber 50. In any of these events, operation of the instrument will be stopped by the microprocessor 124 and an alarm sounded.
15 If, howrver, normal pressurization occuxs, microprocessor 124 instructs delivery valve 68 to open as motor 90 advances, to deliver fluid to the patient through outlet 24, as illustrated in Figure 6. Continuous monitoring of the pressure sensor 91 permits the microprocessor to exercise continuous control over delivery valve 68 t0 SCIeCtIVely restrict the outlet passage 52. This permits 2o the device to insure that the delivery rate is not higher than the requested rate, as for ezample, where gravity siphoning occtus. The microprocessor is also programmed with a selected maximum pressure limit, set by the user through display/i,nput paztel 34, which is used in continuous pressure monitoring.
Escalation of pressure above the selected maximum pressure even with the z5 delivery valve b8 wide open, will result in ,alarm and shut-down of the instrument, indicating that there is some condition. which requires attention, and that fluid is not reach;ng the patient. The ability to select a maximum. pressure limit by the user permits relatively rapid alarms, even at relatively low selected infusion rates.
AMENDED Si-~E

?7.46610675 ROSS CLAPP KORN MONT T-H98 P-021 MHY 08 '96 16:4?
2~ air ~~, ~crns 95i u47o2 ~PE~UUS ~ ~ f~~Y ~~96 m Preferably, the microprocessor is programmed to maintain a relatively constant pressure in outlet pump chamber 50 by selected restriction of delivery valve 68, such constant pressure being just below the masi.mum pumping pressure selected by the operator. This is helpful in insuring that there are no variations s in volumetric delivery which might result from operation at varying pumping pressures.
While fluid is being delivered by advancement of petal assembly 66, the inlet actuator 62 is automatically being withdrawn, transfer valve 64 a already closed, pulling with it flexible will 40 through coupling 44, and fluid is drawn by 1a nega~cive pressure into the inlet chamber 36 through open inlet passage 38.
When the outlet punnping assembly 66 has reached its full extea.ded position, inlet and outlet valves 60 and 68 close and transfer valve 64 opens. Microprocessor 124 then reverses stepper motor 80 for rapid reuaction of petal assembly 66 and a rapid extension of inlet actuator b2 as illustrated in Figure ;7, This permits a very m quick transfer of fluid into outlet pump chamber 50 which will arm the device for the neat delivery cycle. During the outlet pumping portion of the delivery cycle, energy was stored in spring 102 immediately behind the inlet pumping member 62. This energy is used to effect the transfer of fluid so as to drastically reduce the mechanical loading on the main pump motor. The purpose of this is tv allow an 2a increased motor speed during the fluid transfer step which in turn reduces the time taken to effect the transfer as it is principally limited only by the maximum operating speed of the main outlet pump motor 90. Once the transfer of fluid is complete, valve 60 opens and valve 64 closes, and the system is in a condition once more indicated in Figure 5. A meC,hanical stop on shaft 98 limits the amount z~ of movement of the inlet refill actuator 62 so as to avoid pumping any fluid back towards the fluid container 14 as valve 60 opens. Accuracy of the pump is facilitated by having the ability to completely seal the passages, and particularly the transfer passage and the outlet passage. Thus, the outlet chamber can be Wl~f~~~E~7 SHEET

?146610675 ROSS CLRPP KDRN MONT T-8S8 P-022 MRY 08 '96 16:48 QcTius 95i o47oz ~ c~ ? 7 5 ~~ ~ PE~/US 0 ~ ~~'~

pressurized under controlled, non-leaking conditions. A desired pressure can be carefully maintained during delivery by partially opening the outlet valve, which acts as a restriction valve. The fluid delivery can then be completely and accurately controlled.
With reference to Figure 9, in conjunction with Figures 10 through 11, the construction and consiructioa process of one preferred embodiment of a disposable cassette assembly according to the present invention will be more fully understood.
The construction materials, which generally iaclude thin sheet of Zo plastic film, molded plastic tamer plates or moldable plastic for forming plastic carriers, magnetically attractable disks or sheet metal for formiag disks, tubing, and an adhesive, are received, as schematically represented by numeral 130.
The receiving step may include staging for inspection and quality conuol 130x, inspecting 130b, and moving the received material to a storage area 130c. The flexible portion of the cassette comprises two sheets 150 and 152 of flexible film such a PVC sheen or one sheet 182 and a pressure transducer membrane 184, which are cut or blanked at step 132 to as appropriaxe length and shape corresponding to the pump receiving and holdiag section. Typically, the flexible PVC film is received in rolls which are de-reeled, placed under pressure, punched or cut to an appropriate shape, and placed in a container for use in the neat step.
A portion 42 of the coupling mechanism 44 is then welded t:o a second sheet of the film or to a single sheet 182 at step 134. In the preferred embodiment, a flat metallic disk 42 is formed in a flat circular shape having a perimeter ledge therearound. Disk 42 is attached to a shallow plastic tray 138, as shown in Figure 10. Preferably, plastic tray 138 has a rim 139 which surrounds and overlaps ledge 13b as it is attached to the disk 42 as by ultruonic weld.ng, or as by an injection molding process to encapsulate disk 42 within plastic tray 1:38. Disk 42 with the ?1~~6610675 ROSS CLAPP KORN MONT T-898 P
~CT~~S ~'~ ~~ ~ ~~'~
~~~~'~~ ~ ~ ~n~'~ ~~~6 19 2j 87~'S6 plastic tray affixed thereto is positioned on the second elm strip and welded to the film strip i.n step 140.
Other detachable coupling mechanisms could be similarly welded in step 140. For example, a mechanical clip 44a is depicted in Figure 12 which s connects to a pair of clip receptors 4Za anal 46b Which are attached to the cassette and the inlrt actuator, respectively. Such an alternative clip could be advantageous for purposes of specialized Nuclear Magnetic Resonance (NMR) or Magnetic Resonance Imaging (MR.I) fluid infusion. However, the simplicity of the magnetic coupling is normally preferred.
1o At step 142, tubing is cut. An appropriate length of outlet tubing 20 is cut. .An outlet connector plug 144, which is a larger diameter tube and Which receives outlet tube 20 is cut_ A short section of flexible support tubing 146 is cut for insertion into inltt passage 38. An inlet plug connector tubing 148 is cut and an appropriate length of supply tube 18 is cut. The outlet tubing 20 is inserted 15 into the outlet connector plug 144; the flexible support tube 146 is inserted partially into the inlet connector plug; and, the supply tube 18 is partially inserted into the opposite end of the inlet connector plug.
As shown in Figure 10, the inlet and outlet tubing assemblies are placed in alignment between the first sheet 150 and the second flexible sheet Zo to which the metal disk has been welded. The sheets 150 and 152 are sandwiched about the aligned tubing and Welded together to thereby sealingly connect each of the flexible sheets to the outlet connector plug and the inlet connector plug and to define a sealed fluid path through the cassette, including an inlet passage 38, an inlet pumping chamber 36, a transfer passage, an outlet pumping chamber, and 25 an outlet passage. The inlet passage has a portion thereof immediately adjacent the inlet chamber which is narrower than the remainder of the inlet passage to thereby hold the inserted flexible support tube 146 within the inlet passage without permitting it to slide into the inlet chamber. The flexible support tube ,cn, ,, I~ ~u '146610675 ROSS CLRPP KORN MONT T-898 P-d24 MAY 08 '96 16:49 21 '~ ~ 7 ~~ ~ ~~EAI~~ ~ ~ ~~AY s~~~
146 has sufficient resiliency to advantageously prevent collapse a: the inlet passage 38 due to the negative pressure caused during the drawing back of the flexible wall 40 of the inlrt chamber 36. Fluid from supply cube 18 freely flows into the ruler chamber 36 without being restricted by a collapsed inlet passage 38. The support 5 tube 146 is sufficiently flexible to permit complete closure by inlet valve 60, although it has been found that small amaunts of leakage at the inlet valve are not critical because of the rapid rate of the transfer from the inlet chamber 36 to the outlet pumping chamber 50.
ViTith reference to both Figures 10 and 11, one preferred embodiment to of a carrier plate 154 is formed having concave indentations 156 and 158 for receiving the inlet chamber and outlet pumping chamber.. The carrier plate is rigid, relative to the flexible shoets 150 and 152, and may be composed of a plastic, such as PVC (but preferably a copolyester), which has a thickness several times greater than that of the flexible sheets. Also formed in the carrier plate 154 are 15 indented troughs or channels ib0, 162, and 164 corresponding in location to the inlet, transfer and outlet passages. The coughs or channels are shallow, having a radius of curvature 165 corresponding to that of the valves 60, 62, and 64 and are substantially wider than the width of the passages 38, 48 and 52, which are formed between the first and second sheets 150 and 152. This facilitates complete sealing, 2o because the valve head matches the channel size and radius, so that the narrower passages are completely compressed and closed by the valve head and channel.
The welded flexible sheet portion is aligned through locating holes 54 and corresponding locating holes 54a on the carrier plate 154. -thus, the tetra width of the channels will give additional tolerance in the alignment with the passages, which facilitates manufacture without adversely affecting the functionality o~
the cassette.
The construction method as in Figure 9 of the disposable cassette assembly as shown in Figure 10 includes a step 166 of welding the flexible portion ~IEI~IfiFi~ fi?~rE~' ?1~i66106'75 ROSS CLAPP KORN MONT T-8s.38 P-025 MAY 08 ' 96 16: 50 ~: ~ r' ,~ ,; ~, r~ ~T~~ S g 5 / 4 4 r 0 2 ~PEA/U~ 0 8 MAY i996 of the cassette to the rigid carrier. Prior to welding, an adhesive material 168, such as one which can be cured by ultraviolet (U~ radiation, is applied at step 170 to the inlet chamber concave depression 156. The layered flexible assembly is located and welded in place at step 166. Subsequently, a negative pressure is appfied through vent holes 172 to the depression 1S6 to draw the second flexible layer 152 against the concave depression 156. Ultraviolet radiation is applied at step 174 to cure the adhesive while it is drawn firmly against the depression wall.
Alternatively, a positive pressure could be applied to the opposite side of the flexible sheets adjacent the depression, either internal to the two flexible sheets or externally to the first flexible sheet to which the metallic disk is welded.
The negative pressure is preferred as it avoids potential contamination by pressurization inside the cassette aad also avoids potential uneven pressure due to pressing through the magnetic disk.
The outlet pumping chamber cavity has an orifice 176 formed therein through which the door mounted pressure load cell 91 may sense the pumping pressure directly through the second thin flexible sheet 152 of cassette I2.
It will be appreciated that the cassette and instrument could be designed without separate input and output pumping ck~ambers, and that a single pumping chamber activatable both for dewing supply fluid in from a negative 2o head pressure, and pumping the Fluid positively to the patient through a metered control valve could be constricted, without depar<ing from certain aspects of the present invention. However, it is believed that improved reliability, improved diagnostic monitoring, and improved control are advantageously achieved using an input pumping chamber to draw fluid from a supply without regard to positive z5 or negative head height of the supply, in combination with a separate outlet pumping chamber which can be carefully monitored directly through the exterior flexible wall thereof to accurately monitor and apply pressure to the patient.
~4MENDED SH~~~

2146610675 ROSS CLAPP KORN MONT T-698 P-026 MAY 08 '96 16:50 P~TIU S 9 ~ / U ~ ~ p 2 ~ ~' ! 7 c~ ~'~ IPEA/US 0 8 MAY 1996 While the foregoing alternative embodiment has been described primarily with respect to a double-sheet construction in which one of the flexible sheets is attached to a rigid carrier and thereby rigidified, :it has been found that other advantages may be obtained through reduced cost, both in the materials s used and in the processing steps required through the construction of an embodiment of the disposable cassette in which a single flexible sheet of PVC
~1m is welded to a rigid curier formed of a thicker injection-molded plastic, preferably a copolyester plastic. Also, as will be more fully understood from the description below, additional advantages have been obtained with unique, improved manufacturing methods - particularly, improved RF welding of thin sheets of PVC to relatively thicker, rigid carrier composed of copolyester. The resulting structure produces a fluid tight flow path between the single flexible sheet and the rigid carrier. The floor path includes an inlet passage, an inlet pumping chamber (i.e, suction pump chamber), a transfer passage, an outlet pumping chamber and 15 an outlet passage.
As noted previously, one key aspect for maintaining accurate fluid delivery from a cassette, which may be used in a pump for. drawing fluids from a negative head height, is in the capability of a cassette traasfer valve and an outlet valve (or delivery valve) to completely and reliably shut off all fluid flow.
The 20 outlet pumping chamber, or delivery pumping chamber, can be made completely fluid tight through valve operation. Leakage back from the outlet pumping chamber to the inlet pumping chamber is eliminated, and any delivery of fluid through the outlet valve can also be precisely controlled without any unwanted flow or with precisely controlled restricted flow. This capability must also be 25 provided in conjunction with weld seams capable of holding both positive and negative fluid pressures of 15 psi or more exerted over the entire surface area of the fluid flow pathway, both in the inlet, transfer and outlet channels and also in the inlet and outlet pumping chambers_ aMENGFD SHEET

146610675 ROSS CLRPP KORN MONT T-89B P-027 hIRY 08 '96 16:51 -, ~ ~; % ~ ~CTI~ S 9 5 l 0 ~+ 7 p 2 . ~ 7 . ~ ~~~,~~~ ~ ~ r~~AY 1996 The unique structure and construction of a preferred embodiment, having a single flesable layer 182 wrelded to a rigid carrier 180, will be more fully understood with reference to Figures 13 through 22, beloov. Figure 13 is a perspective assembly view of this alternative preferred embodiment of a s disposable cassette. Figure 14 is a top plan view of the assembled cassette of Figure 13. Figure i5 is a bottom plan view of the assembled cassene. Figure 16 is a side section view, taken along a center line of the cassette of Figures 13-15, according to the present invention. Figure 17 is a cross-sectional view, takes along s~xtion lines 17-17 of Figure 14. Figures 18 and 19 are cross-sectional views, 1o taken along section lines 18-18 and 19-19, respectively, of Figure 16.
Figure 20 is a sectional vices, taken along section line 20-20 of Figure 14. Figure 21 is a partial end view from the inlet end of the inlet boss 186 of the inventive cassette, according to the alternative construction, using a single fIeaible sheet i82.
Figure 22 is a partial enlarged, tross'sectional detail of the outlet boss 188 and 15 tapered hole tube connector 196 formed therein.
Referring now to Figures 13 and 14, one preferred embodiment of a disposable cassette includes a rigid carrier plate 180, formed as with injection molding, having a first concave indentation 156 for forming the inlet pumping chamber and a second concave indentation 158 for forming the outlet pumping 1o chamber. The carrier plate 180 is preferably composed of a copolyester plastic material, such as Eastman Ektar DN001, and has a sufficient thickness, so that it is rigid relative to the thin, flexible PVC sheet 182. The single sheet 182 is preferably composed of another, more flexible plastic, such as medical grade PVC.
PVC sheets available from Ellay, I,n,c., under the designation 30-2127, have been 2s found to meet the requirements of this invention. The thickness of the carrier plate 180 is generally several times thicker than that of the; flexible sheet 182, as for example, a flexible PVC sheet 182 having a thickness of about 0.016"
(about 1.6 mil) provides good flexibility and strength, and the rigid carrier 180 having a 11~.1cn~ntn cuccT

?A6610675 ROSS CLRPP KORN MONT T-898 P-028 MRY 08 '96 16:51 1 ~: I ~' 'A~ PCTIUS 95/ 04702 IPFA,~US 0 8 SAY 199 thickness o~ about 0.080" (about 8_0 mil) provides strength, rigidity and øumeasional s~~b~ty for ate purposes of the present invention.
The flexible sheet is welded to the rigid carrier, using a radio frequency welding technique. The dies are made of brass or other radio fzequenry conducting material having appropriate cavities and channels formed therein, corresponding to the concave indentations for the inlet pumping chamber sad the outlet pumping. chamber, as well as indentations for the channels, induding the inlet channel, the transfer channel sad the outlet channel, which define the fluid flow path 200 through the cassette. The thin PVC film 182. is preferably held in 1o position to the upper die through the use of a vacuum, which is applied through orifices in the upper die, The rigid carrier 180 is placed in the lower di,e, appropriately aligned as by using alignment holes 54. The upper sad lower dies are pressed together, in alignment with each ocher, to squeeze together a bottom surface 204 of the flexible sheet 182 and a top flat surface 202 of the rigid 1s c::arrier 182. An electromagnetic RF signal is communicated through the dies, from one RF conducting die to the other and through the plastic materials "sandariched" therebetween. Specific inventive aspects o~ this process will be explained more fully below with respect to Figures 23 thraugh 27, below.
In the preferred embodinnent, prior to welding the single plastic 2o sheet 180 on the rigid carrier 182, a pressure-sensing orifice 176 will have been formed through the rigid carrier at the outlet pumping chamber 158.
Preferably, the orifice 176 is circular in shape and rn.ay be formed into the rigid carrier during the injection molding process by which the rigid carrier is farmed_ A thin plastic membrane 184, which may be composed of the same PVC f~11m materials as the z5 sheet 182, having a thickness of about 0.016" (about 1.6 mil), is cut, as by a coining process, to a predetermined size and shape for covering the pressure-sensing orifice 17b. The coined membrane 184 is secured, covering the orifice 176. Preferably, RF welding is used to secure the membrane 184 in place.
~M~~uoEO s~~~r 146610675 ROSS CI..RPP KORN MONT T-898 P-029 MRY 08 '96 16:52 ;~ .~~ , p~Tl'~~ 95,1 X4702 ~PfA/1~~ ~ ~ ~;1AY I99~
Then, the single flexible sheet of PVC is welded to the rigid carrier, as described above.
Also formed in the rigid carrier is a depression 160, corresponding to the inlet channel, which communicates with the inlet pumping Chamber 156.
s There is also an indentation 162, corresponding to the transfer passage between inlet pumping chamber 156 and outlet pumping chamber 158. Extending from outlet pumping chamber 156 is a depression, corresponding to as outlet channel 164. The inlet channel 160 and the outlet channel 164 do not extend entirely across the flat top surface 202 of the carrier 180, but rather communicate to through an inlet orifice 186 and an outlet orifice 190. Inlet orifice 1.86 extends through an inlet boss 188, formed on the bottom surface of the rigid carrier 180_ Also, outlet orifice 190 communicates with channel 164 and into as outlet boss 192, formed on the bottom surface of rigid carrier 180. A tapered inlet hole 19h serves for connexion of inlet tubing 18 for receiving fluid to be infused, 15 and a tapered outlet hole 196 serves for connection to thr outlet tubing 20, which will be used to infuse fluids to a patient. In each instance, the inlet tubing 18 or the autlei tubing 20 will be sealingly secured to the cassette as by adhesive or ocher bonding method, for eaunple, ultraviolet curing adhesive_ Preferably, a solvent bond is used for iu speed and low cost, which, together with the tapered 2o construction of the receiving holes, results in mechanica~".y seev~re and fluid-sealed bondiag_ For example, Cyclohesanone is one solvrent which can be used, as ii will paxtially dissolve both the PVC and the copolyester, which then blend together for effective bonding_ The inlet orifice 186 communicates from the inlet hole 194 and 25 attached tubing into the inlet channel 160, which in turn communicates with the remainder of the flow path 200. The flow path 200 is essentially defined by a perimeter edge 198, between the top flat surface 202 of the rigid carrier and the indentations in the top surface of the rigid carrier, which indentations and ~.an~~!n~n e!.~~-T

'146610675 ROSS CLRPP KORN MONT T-858 P-030 MRY 08 '96 16:52 ~cTius ~~r 047.02 ii~~~,/US 0 ~ SAY i9~6 perimeter edge 198 define the fluid flow path 200. Fluid flow path 200 is enclosed by welding the thin PVC sheet 182, as with a radio frequency weld formed at the interface between the top surface 202 and the rigid carrier and the bottom surface 204 of the PVC film., which weld 206 extends entirely around the perimeter edge 198, defined by the indentations of the fluid flow path. As with the double fleziblc sheet embodiment, described above, a metal disk 42 will be attached to the top surface 205 of sheet 182, as described above, wish respect to attachment of the disk 42 to the second sheet 152 in the double sheet cassette construction.
so Although speafic embodi.meatx of the invention have been illustrated in the accompanying drawings and described is the foregoing dttailed description, it will be understood that the invention is not limited to the enabodim.ents disclosed, but is capable of numerous rearrangements, modifications, and substitutions of pare and elements without departing from the spirit of the i5 invention. It is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended cl.ainas to which the inventors are legally entitled.
Whea the disposable cassette is placed in the pumping apparatus, as shown in Figure 4, inlet channel 160 will be placed adjacent to inlet valve 60.
z0 Metallic disk 42 will become removably coupled with magnet 46 for actuation, both in reuaction and in compression with inlet pumping actuator 62. As the magne~ricallp-coupled inlet pumping chamber 50 may draw fluid from a negative height, the low pressure within the inlet passage will tend tea collapse the flexible sheet 182 into the inlet channel 160_ Such a restriction or a closure could interfere 25 with pump operation. Ia order to prevent this, first and second support projections 208 and 210 are advzntageously formed, projecting upward from the bottom of channel 160, a short distance above flat top surface 202. The flexible sheet 182 is supported upward by projections 208 and 210 from either end of the ~~MENDED SHEET

'1~166106?5 ROSS CLAPP KORN MONT T-89B P-031 MRY 08 '96 16:53 ~Tius 9~~ u4?off ~ ~~ T ;l ~6 ,~~~s ~ s ~~~~Y ~~~a 2~
inlet channel 160: The channel area between projections 208 and 210 is not provided with projections, so that valve actuator 60, acting against sheet 182, can overcome the upward tension, thereby closing the inlet passage. It has been found that when valve b0 is actuated to a "dosai" position, a "clidiing" noise can result s whoa a single layer of flexible him 182 is pushed. To reduce the noise level, it has been found advantageous to insert a silicon tubing 146, positioned between projectioxzs 208 and 210 and enclosed between channel 160 and PVC Layer 182.
The silicon tubing 146 is not readily welded with RF welding such that its interposition, between the flexible sheet 182 and the channel 160 of cassette rigid 1o carrier 180, does not interfere with RF welding of the sheet 182 to rigid carrier 180 and does not require a separate mandrel wel3ing operation to prevent the opening co the center of tubing 146 from becoming sealed shut_ It has also been found that, to the extent that a perfect seal around the tubing 146 is not obtained during the welding procedure, tht capacity of inlet pumping ~s chamber 156 is, nevertheless, sufficiently larger than the caps«ty of outlet pumping chamber 158, so that small amounts of leakage at the inlet valve 60 can be tolerated without adversely affecting the operation of the pumping cassette.
As discussed above with respect to the double-sheet cassette, and as discussed further below, the accwacy of the pumping eassttte is obtained through complete 2o sealing of the transfer channel 62 and the outlet channel 164 on either side of the delivery pumping chamber 158.
To facaliute complete dosuxe of txansfer passage 162, upon actuation of transfer valve 64, a unique welding procedure has been implemented, as will be discussed more fully below with respect to Figures 23 through 27. It should be 25 noted with respe~ to Figure 14 that Applicants' inventive cassette has a first transfer valve area 212, against which valve b4 will impact. At the perimeter edge 198 alongside area 212, there are welds 214 which are specially formed to avoid extrusion of weld material into channel 162. Thus, the valve 62 can seal ,AMENDED SHEET

'146610675 ROSS CLRPP KORN MONT T-898 F'-032 MRY 08 '96 16:54 ~cT~us~95i 04702 a 1 rj 7 . ~ ' ~F~~/~~ ~ ~ ~riAY 199 completely along the radius of the channel 162, from one ,side of perimeter edge 198 to the other side. At channel 162, there is a second area 216, which is adjacent to the output pumping chamber 158, in which mechanically sueagthened welds 218 are provided along both sides of perimeter edge 198. As the transfer area valve area 212 will remain in contact with valve actuator 64, there will be adequate mechanical strength to avoid weld separation, while uniquely providing a smooth weld transition of the channel 162 radius at the perimeter edge 198. The area 216, at which there is no valve contact and at which the maximum pressures associated with controlled pumping in outlet pumping i0 chamber 158, will be securely held. with the increased sueugth welds 218.
As discussed above, in the outlet puzxtping chamber 158, there is an orifice 176 formed, which has a transducer membrane 184 welded rhereover.
With reference to Figure 19, it will be seen chat the preferred construction of the pumping chamber includes the orifice 176, having a chamfer edge therearound, 1s with znexnbrane 184 welded thereinto. Thus, a substantially flat transducer surface 185 results across the opening of orifice 176. The weld around the perimeter or membrane 184 can be created with stax~dard :KF welding practices, because normal extrusion of material from such a weld, either into the orifice or into chauiber 184, does not interfere with the operation of the transducer 2o membrane.
The portion of film 182, which overlays the outlet pumping chamber 158, is provided with an upward radius through the use of concavity in the upper welding die and a vacuum which draws the flexible sheet 182 up into the concave area before welding. The welding thrn secures the additional "bulge"
z5 of sheet 182 in the appropriate radius fashion, so that pumping can be accomplished by the pump actuator 70, as discussed above with respect to the double-sheet cassette.
AMEf~t~c~ SHEEt 146610675 ROSS CLRPP KORN MONT T-898 P-033 MRY 0B '96 16:54 ~~~~5 95/ 04 p IPEAIUS 0 MAY 19~~

In the outlet passage 1b4, there is a valve closure area 220, against which outlet valve 68 will be actuated. The portion of flexible sheet 182, which overlays area 220, is secured to tht rigid carrier 180 with unique non-extrusion welds 222 along the perimeter edge 198. As with the transfer area 212 and transfer valve welds 214, these welds arc formed without extrusion of mdxed plastic into the channel 164 during welding. This advantageously allows complete closure to be obtained. Valve 68 ,cnay also be adjustably positioned to provide a restriction, and the welds 222 are accurately formed so that the restriction provided with valve 68 can be accurately accomplished without unwanted leakage. Also, outlet 1o passage 164 is pmvided with strong welds 226, which create strengthening "beads~
as a result of small amounts of extrusion material therealong. These ~beads~
provide additional mechanical strength but are not in the area 220 where interference with the valve anion might have caused a problem. It has been found that the channel areas 216 and 224 can be subject to some of the highest ~5 stress in the cassette. There can be relatively high pressure within pumping chamber 158, and the large surface area of sheet 182, which is exposed to the pressure within pumping chamber 158, can pull the areas 216 and 224 which arc immediately adjacent to the outlet pumping chamber 158_ Thus, this construction, with increased strength welds 214 and 226 in this area, provides 2o advantages over other constructions, while the valve areas 2'12 and 220 with non-interferes welds 214 and 222 allow complete transfer valve sealing and complete outlet valve sealing without unwanted leakage.
Deferring now to Figure 15, which is a bottom view of the rigid carrier 180 for use with a single flexible sheet. It will be noted that at the bottom z5 of rigid carrier 180, apposite transfer channel 162 and opposite outlet channel 164, them are indentation areas 228 and 230, respectively. These indentations arc formed during the injection molding of rigid carxier 180 and provide advantages 146610675 ROSS CLRPP KORN MONT T-898 P-034 MRY 0B '96 16:55 ~Tius 9~i o4 ~oz ~~ 1 c' / ~~ .'~~'=> ~t~E~r/US 0 8 MAY 1996 according to one embodiment of the welding process by which the special welds 214 and 218 and welds 222 and 226 are formed.
With reference to Figures 23 and 24, the special welding method will be more fully explained. Figure 23 is a schematic depiction of a cross-section of 5 welding dies 232 and 234, shown in operation, welding flexible sheet I82 to the rigid carrier 180. It has been found that with RF welding of a thin sheet 182 having a thickness 236, as for example, 0.016" (1.e. 1.6 mil), to a rigid carrier 180 having a thickness 238, as for example, 0.080" (1.e. 8.0 mil), presents difficulties for radio ~xequencywelding. In the R.F welding process, the typical result i's for the Zo melting of the hottest point generated in the pizstic to occur at the mid point 242, between the entire overall thickness 240, of both pieces of plastic. When the two plastic materials are of the same thickness, the results are satisfactory.
However, when a thin sheet is welded to a thicker sheet, then difficulties arise, as all of the melting will occur at the thickest sheet and bonding will not occur at the interface 15 between surface 202 and 204_ This problem is further exacerbated. by the dissimilarities of the materials, with the thinner sheet being a PZTC material and having a particular melting temperature and a particular reactive characteristic to RF signals, and the copoiyester of the rigid carrier which has a higher melting temperature and its own characteristic reaction to RF signals. Thus, in order to 20 successfully weld these dissimilar mzterials, having different thickness, Applicants have uniquely developed a process by which the upper die 232 is preheated to a temperature TU244, and the lower die 234 is heated to a desired temperature TL246. Uniquely and unobviously, the lower die is not heated to a high temperature despite the higher melting temperature of the copolyester and the z5 thickness of the copolyester, but rather the upper die 232 is heated to a temperature TU244, which is higher than the temperature TL246. It was found that this effectively moves the hot point from mid-point 242 up to the interface between surface 202 and surface 204, at a distance 236 from the face of die 232 and :i~IENDEO SHEET

146610675 ROSS CLRPP KORN MONT T-8'3B P-035 MAY 08 '96 16:55 ~p~I~~ 95/ 047p~
~PEA/US 0 8 ~~~ ~'~ i~9~

at a distance 238 from die 235. Also, in order to avoid welding channel 62 to the film 182, and thereby closing the passage, the die face 232 terminates along each edge of the channel as with the cavity 252. The lower die face also terminates at a corresponding location as to the formation of the cavity 254 in die 234. It was discovered that this arrangement resulted in a weld, as shown schematically at 260, having a projection 262 which extended into the passage. Without control of The amount of the extrusion 262 was difficult. In order to facilitate control, a non-conductive spacer 264 was inserted into the cavity 252 and a non-conductive spacer 2b6 was inserted into the lower cavity 254. These spacers were made of a to durable material, such as delrin, which does not conduct and is not effectively melted by the RF electromagnetic signal_ Thus, it was found that a weld, such as that schematically depicted at 268, could be formed, having a "bulge" of extruded material 270; which was more readily controlled along a chamfered corner 265 of the upper delrin spacer 264.
Tht "bulge" 270, nevertheless, was found to potentially interfere with the closure of either valve 62 or valve 64 such that a subsequent welding operation, as shown in Figure 24, was implemented. In Figure 24, which is a schematic cross-sectional depiction of the subsequent welding step, an upper die 272 is provided with a radiused surface 274, and a lower die 276 is provided zo with a concave radiused surface 278. Although previous wisdom for RF
welding has been that curved surfaces were not candidates for RF welding, careful control of the spacing between upper die 272 and lower die 276, rather than careful conuol of the pressure, was found to be effective to maintain a weld at a curved surface, partially into the radiused channel 62. In this manner, the "bulge"

could be effectively flattened to a radius corresponding to that of channel 162, so that the valve could. completely seat therealoz~.g and have complete closure of the channel 162. A similar process was used with respect to the valve closure at the outlet 164. To further avoid any inadvertent extrusion into the channel, a delrin ~~FNnF~. cHFGT

46610675 ROSS CLAPP KORN MONT T-898 P-036 MGY 08 '96 16:56 ~;'~~'~a~ 9 0 4 7 0 r, y' ~
21 ~; l .~ ' ~~°cf~l~~ NBA f spacer 280 having a radiusod surface 282 was used in the upper die 272, and a delrin spacer 284 having a concave radiused surface 286 was provided in the lower die, thereby effectively damming any extrusion to the compression between film 182 and carrier 180 caused by the compressive pressure between the dekin spacers. Tn order to maiaatain appropriate curved surfaces, welding the distance 190 between the convex die surface 274 and the concave die surface was carefully maintained as with an adjustable mechanical spacer 192, against which the upper die 272 and the lower die 276 abutted during the welding process.
to Referring now to Figure 25, a further advantageous preferred method of achieving a weld between a flexible PVC sheet and a rigid carrier of copolyester is schematically depicted. In this embodiment, the upper RF die 232 and the lower die 234 are substantially the same as in the method described with respect to Figure 23. However, the delrin spacers within cavities 252 and 254 are constructed differently, and the operation of the RF input is also modified.
In this instance, the preheating with temperature 244 and 24b is again implemented in order to properly position the "hat" spot, or the weld spot, az the interface between surfaces 204 and 202, as described above with respect to the method depicted in Figure 23. The upper delrin insert 294 is provided with square 2o comers 295, extending in the valve contact areas 212 and 242, so that the special welds 214 and 226, which allow complete sealing, are as dapicted in Figure 25.
The squaring of the corner 295 did noi, in and of itself, result in the weld as depicted, but it was further required to modify the RF 'on" time, as depicted on the graph shown in Figure 2b. The recommended weld time ('TR), which previously resulted in a good weld as shown in Figure 23 at 268, did not successfully cause the weld to flow down along the radius of channel 62, as shown at 296 of Figure 25. The pressure up to the edge, as provided by corner 295, merely resulted in a damming effect, which caused all of the extrusion co move :~MEf~~nr~ ~~~~r 'i.46610675 ROSS CLRPP KORN MONT T-898 P-037 MRY 08 '96 16:56 P~y~i~s~ 95/ 0~+7Q2 ' ~~~AIUS ~ 8 ~l~,Y ~"95 toward the exterior, as- shown at 298. I-low~eve~r, increasing the RF weld time to a rime (Z'B), as shown in Figure 26, caused the cornet at the junction between chanarl 62 and upper surface 202 of the rigid tuner 180, to begin melting, and the compression pressure provided by delrin spacer 94, and particularly, the sharp s corner 295 caused the weld to flow radiantly along channel 62. By carefully controlling the increased RF 'va" time TB and by maintain proper pressure 256 and 258, a smooth truuition weld, as shown at 296, resulted at all welds 214 and 222.
QUith refrrenee to Figure 27, the modified coastmcrion of ddrin to spacer 294 is depicted is which radiuxd corners 295 were maintained is the area 216 and 224, where strong welds were required. Thus, weld beads 270, as shown in Figure 23, and the sharp corners 295 were formed in those valve sealing areas 212 and 220, so that the special welds 214 and 222 resulting, having a configuration a depicted at 296 is Figure 25_ AMENDF~1 cuter

Claims (20)

In The Claims:

1. A disposable cassette for use in as infusion pumping instrument of the type having an inlet valve, as inlet fluid actuator, a transfer valve, an outlet fluid actuator, as outlet valve and means for replaceably holding a disposable cassette, said disposable cassette comprising:
(a) first sad second flexible sheets sealed along interior surfaces defining an inlet passage, as inlet fluid chamber, a transfer passage, an outlet fluid chamber, an outlet passage and means for locating said defined passages and fluid chambers adjacent corresponding valves and fluid actuators in said pumping instrument;
(b) a relatively rigid carrier to which an exterior surface of said fast flexible sheet is attached sad having concave indentations correspondingly sized sad located for receiving said inlet fluid chamber and said outlet fluid chamber and for constraining movement of said first flexible sheet thereinto; and (c) means operatively associated with said inlet fluid chamber for expanding the volume of the inlet fluid chamber corresponding to retraction of the inlet fluid actuator away from the cassette and for decreasing the volume of the inlet fluid chamber corresponding to advancement of said inlet fluid actuator against said cassette, wherein said means for expanding the volume of said inlet fluid chamber comprises a magnet rigidly affixed to said inlet actuator and a magnetically attractable disk rigidly affixed to said second sheet at the inlet fluid chamber so that the magnet on the actuator and the disk on the cassette are magnetically coupled for moving said second sheet apart from said first sheet in the inlet fluid chamber upon retraction of said inlet actuator.

2. A disposable cassette for use in an infusion pumping instrument of the type having an inlet valve, an inlet fluid actuator, a transfer valve, an outlet fluid actuator, as outlet valve sad means for replaceably holding a disposable cassette, said disposable cassette comprising:
(a) first and second flexible sheen sealed along interior surfaces defining an inlet passage, an islet fluid chamber, a transfer passage, an outlet fluid chamber, as outlet passage and means for locating said defined passages sad fluid chambers adjacent corresponding valves and fluid actuators in said pumping instrument;
(b) a relatively rigid carrier to which as exterior surface of said first flexible sheet is attached and having concave indentations correspondingly sized and located for receiving said inlet fluid chamber and said outlet fluid chamber and for constraining movement of said first flexible sheet thereinto; and (c) means operatively associated with said inlet fluid chamber for expanding the volume of the inlet fluid chamber corresponding to retraction of the inlet fluid actuator away from the cassette and for decreasing the volume of the inlet fluid chamber corresponding to advancement of said inlet fluid actuator against said cassette wherein said means for expanding the volume of said inlet fluid chamber includes:
(i) detachable coupling means having a first portion thereof rigidly affixed to said inlet actuator, having a second portion thereof rigidly affixed to the second sheet at the islet chamber, and having a magnetic coupling between the inlet actuator and the second sheet interactive between the first sad second portion with coupling force, so that the second sheet is pulled away from the first sheet upon retraction of the inlet actuator and so that the interactive mechanism can be manually separated for replacement of the disposable cassette; and (ii) means for affixing an exterior surface of said first sheet to the concave depression in said relatively rigid carrier so that it is not drawn with the retraction of the second sheet at the inlet fluid chamber.

3. A disposable cassette for use is an infusion pumping instrument of the type having as inlet valve, as inlet fluid actuator, a transfer valve, as outlet fluid actuator, an outlet valve and means for replaceably holding a disposable cassette, said disposable cassette comprising:
(a) first and second flexible sheets sealed along interior surfaces defining an inlet passage, an inlet fluid chamber, a transfer passage, an outlet fluid chamber, an outlet passage and means for locating said defined passages and fluid chambers adjacent corresponding valves and fluid actuators in said pumping instrument;
(b) a relatively rigid carrier to which as exterior surface of said first flexible sheet is attached and having concave indentations correspondingly sized and located for receiving said inlet fluid chamber and said outlet fluid chamber and for constraining movement of said first flexible sheet thereinto; and (c) means operatively associated with said inlet fluid chamber for expanding the volume of the inlet fluid chamber corresponding to retraction of the inlet fluid actuator away from the cassette and for decreasing the volume of the inlet fluid chamber corresponding to advancement of said inlet fluid actuator against said cassette wherein said means for expanding the volume of said inlet fluid chamber includes:
(i) detachable coupling means having a first portion thereof rigidly affixed to said inlet actuator, having a second portion thereof rigidly affixed to the second sheet at the inlet chamber, and having a removably attachable mechanical clip and corresponding clip receptors on the second sheet and the inlet actuator interactive between the first and second portion with coupling force, so that the second sheet is pulled away from the first sheet upon retraction of the inlet actuator and so that the interactive mechanism can be manually separated for replacement of the disposable cassette; and (ii) means for affixing an exterior surface of said first sheet to the concave depression in said relatively rigid carrier so that it is not drawn with the retraction of the second sheet at the inlet fluid chamber.

4. A disposable cassette for use in an infusion pumping instrument of the type having as inlet valve, an inlet fluid actuator, a transfer valve, an outlet fluid actuator, as outlet valve and means for replaceably holding a disposable cassette, said disposable cassette comprising:
(a) first and second flexible sheets sealed along inferior surfaces defining as inlet passage, an inlet fluid chamber, a transfer passage, an outlet fluid chamber, as outlet passage and means for locating said defined passages and fluid chambers adjacent corresponding valves and fluid actuators in said pumping instrument;
(b) a relatively rigid carrier to which an exterior surface of said first flexible sheet is attached and having concave indentations correspondingly sized and located for receiving said inlet fluid chamber and said outlet fluid chamber and for constraining movement of said first flexible sheet thereinto, wherein said relatively rigid carrier further comprises:
(i) a shallow inlet trough having a concave cross-sectional shape and sized wider than said inlet passage as defined by said first and second flexible sheets so that alignment of said passages in said troughs is simplified;
(ii) a shallow transfer trough having a concave cross-sectional shape and sized wider than said transfer passage a defined by said first and second flexible sheets so that alignment of said passages is said troughs is simplified;

(iii) a shallow outlet trough having a concave cross-sectional shape and sized wider than said outlet passage as defined by said first and second flexible sheets so that alignment of said passages in said troughs is simplified; and (iv) said inlet, transfer and outlet valves sized and shaped corresponding to the width and shape of the troughs so that complete closure by the corresponding valves is facilitated; and (c) means operatively associated with said inlet fluid chamber for expanding the volume of the inlet fluid chamber corresponding to retraction of the inlet fluid actuator away from the cassette and for decreasing the volume of the inlet fluid chamber corresponding to advancement of said inlet fluid actuator against said cassette.

5. A method of constructing a disposable cassette for use in an infusion pumping instrument of the type having as inlet valve, a pumping element, as outlet valve, and a disposable cassette receiving and holding section, said method comprising the steps of:
(a) cutting first sad second this flexible sheets of plastic material in a shape for operative association in the receiving sad holding section of the infusion pumping instrument;
(b) welding a magnetically retractable disk to the exterior surface of the second thin flexible sheet of plastic material;
(c) welding the first and second thin flexible sheets together to define therebetween a fluid path comprising an inlet passage, a fluid chamber corresponding to the location of the disk, and an output passage, which inlet and outlet passages are in fluid communication with the fluid chamber and are welded to the inlet sad outlet cut tubing;
(d) forming alignment holes exterior to the fluid path in the welded plastic film sheets;

(e) forming a carrier plate sized corresponding to the size of the cut film sheets and defining a concave fluid chamber depression; and bonding the Welded film sheen to the carrier plate, including bonding the fast sheet to the concave fluid chamber depression to rigidly hold the first sheet opposite the welded disk at the fluid chamber so that the second sheet can be independently drawn away from the fast sheet to increase the volume is the fluid chamber.

6. A disposable cassette for use is an infusion pumping instrument of the type having an inlet valve, as inlet fluid actuator, a transfer valve, as outlet fluid actuator, as outlet valve and means for replaceably holding a disposable cassette, said disposable cassette comprising:
(a) a relatively rigid carrier having as inlet channel, an inlet concave indentation, a transfer channel, an outlet concave indention with a pressure sensor orifice therein and an outlet channel;
(b) a first flexible sheet sealingly affixed overlaying said pressure sensor orifice in said outlet channel;
(c) a second flexible sheet overlaying said relatively rigid carrier sad sealed along interior surfaces between said relatively rigid carrier sad said second flexible sheet, thereby defining an inlet passage, as inlet fluid chamber, a transfer passage, as outlet fluid chamber and an outlet passage;
(d) means formed on said disposable cassette for locating said defined passages and fluid chambers adjacent to corresponding valves and fluid actuators is said pumping instrument; and (e) means operatively associated with said inlet fluid chamber for expanding the volume of sad inlet fluid chamber corresponding to retraction of said inlet fluid actuator away from said disposable cassette and for decreasing said volume of said inlet fluid chamber corresponding to advancement of said inlet fluid actuator against said cassette.

7. A disposable cassette as in Claim 6 wherein said means for expanding said volume of said inlet fluid chamber comprises a detachable coupling means having a first portion thereof rigidly affixed to said actuator, having a second portion thereof rigidly affixed to said second flexible sheet at said inlet chamber, and having a coupling force mechanism interactive between said first and second portions of said detachable coupling means, so that said second sheet is pulled away from said relatively rigid carrier upon retraction of said inlet actuator and so that said coupling force mechanism can be manually separated for replacement of said disposable cassette in said infusion pumping instrument.

8. A disposable cassette a in Claim 6 wherein said orifice in said outlet concave indentation of said relatively rigid carrier is a circular orifice surrounded by a substantially circular lower rim and said first flexible sheet is sealingly affixed around said lower rim for forming a flexible diaphragm which is exposable at said outlet chamber to a pressure sensor held in said pumping instrument adjacent to said orifice and said flexible diaphragm when said cassette is held in said pumping instrument.

9. A disposable cassette as in Claim 6 further comprising a flexible support tube interposed in said inlet passage between said inlet channel of said relatively rigid carrier and said second flexible sheet sealed therealong, said flexible support tube having sufficient resilience to hold said inlet passage open when fluid is drawn into said inlet chamber upon retraction of said second flexible sheet.

10. A fluid infusion pump comprising:
(a) a disposable cassette having a relatively rigid first wall of at least one pumping chamber and a movable second wall of said at least one pumping chamber defining an inlet passage, an outlet passage and at least one pumping chamber between said inlet passage and said outlet passage;
(b) a pump body for receiving said disposable cassette in a fixed operating relationship;

(c) an actuator mounted in said pump body and activatable for reciprocal advancement and retraction with respect thereto and adapted to confront said movable second wall when said disposable cassette is received in said pump body; and (d) a detachable coupling between said pump actuator and said movable second wall so that fluid is expelled from said at least one chamber on advancement of said actuator and so that fluid is positively drawn into said at least one chamber upon retraction of said actuator, said detachable coupling including a magnetically attractable disk attached to said movable second wall, and a mechanism attached to said actuator for reciprocation therewith, which mechanism is magnetically attracted to said magnetically attractable disk attached to said movable wall.

11. A liquid infusion pump comprising:
(a) a disposable cassette having an inlet passage and a transfer passage and forming at least one chamber between said inlet passage and said transfer passage, said at least one chamber having a movable wall with a magnetically attractable means attached to said movable wall;
(b) a pump body for receiving said disposable cassette in a fixed operating relationship;
(c) a magnetic actuator mounted in the pump body for reciprocation with respect thereto, and adapted to confront and to magnetically and detachably engage said magnetically attractable means attached to said movable wall when said disposable cassette is received in said pump body;
(d) a pump drive for advancing and retracting said magnetic actuator, whereby fluid is expelled from said chamber on such advancement, and is drawn into the chamber as the actuator is retracted;

(e) an inlet valve actuatable against said inlet passage and retractable therefrom;
(f) a transfer valve actuatable against said transfer passage and retractable therefrom;
(g) means for retracting said inlet valve from said inlet passage when said magnetic actuator is retracting and for actuating said inlet valve against said inlet passage when said magnetic actuator is advancing; and (h) means for actuating said transfer valve when said magnetic actuator is retracting and for retracting said transfer valve when said magnetic actuator is advancing so that fluid is drawn by negative pressure into said inlet chamber so that fluid is positively drawn is only from said inlet passage and fluid is expelled only from said transfer passage.

12. A pump for parenteral administration of fluid into a patient at a selectable rate comprising:
(a) a disposable cassette having a relatively rigid carrier and a flexible sheet sealingly secured thereto defining a flow path between and inlet and as outlet, including as inlet passage, a supply chamber, a transfer passage, an outlet, a pump chamber and an outlet passage located along said flow path said supply chamber positioned in said flow path of said disposable cassette between said inlet passage and said transfer passage leading to said outlet pump chamber and said supply chamber, including a magnetically attractable movable wall and a relatively rigid wall;
(b) an instrument body having a compartment for receiving said disposable cassette;
(c) an outlet pumping element associated with said instrument body adjacent to said compartment for receiving said disposable cassette and said confronting outlet pump chamber;

(d) activation means for activating said outlet pumping element to reduce the volume of the outlet pump chamber at a rate dependent upon a selected rate;
(e) a magnetic refill actuator carried by said instrument body for movement toward and away from said supply chamber and adapted to confront and detachably hold said magnetically attractable movable wall of said supply chamber;, (f) as inlet valve actuatable to close or to open said inlet passage positioned between said inlet and said supply chamber of said disposable cassette;
a transfer valve actuatable to close or open said transfer passage between the supply chamber and the outlet pumping chamber, (h) a delivery valve actuatable to close or open said outlet passage between said pump chamber and said outlet; and (i) control means for, at first times, closing the delivery inlet valves, opening the transfer valve, and retracting the pumping element from the outlet pump chamber while advancing the refill actuator towards the supply chamber, whereby the pump chamber is refilled, and at second times, opening the delivery valve and inlet valve and closing the transfer valve while advancing the outlet pumping element to reduce the volume or increase the pressure of the outlet chamber while retracting the refill actuator and supply chamber wall therewith for positively drawing fluid through said inlet passage into said supply chamber.

13. A disposable cassette for use in an infusion pumping instrument of the type having an inlet valve, an inlet pump actuator, a transfer valve, an outlet pump actuator, an outlet valve and means for replaceably holding a disposable cassette, said disposable cassette comprising:

(a) a rigid carrier, having top and bottom surfaces and having a fluid path formed on said top surface, said fluid path including:
(i) an inlet orifice;
(ii) an outlet orifice;
(iii) a concave inlet channel, communicating with said inlet orifice;
(iv) a first concave pump indentation, communicating with said concave inlet channel;
(v) a second concave pump indentation, having an access hole extending from said second pump indentation to said bottom surface of said rigid carrier;
(vi) a concave transfer channel communicating between said first and second concave pump indentations; and (vii) a concave outlet channel communicating between said second concave indentation and said outlet orifice;
(b) a flexible sheet, sealingly welded to said top surface along a perimeter edge of said fluid path immediately adjacent each of said orifices, concave channels and concave pump indentations, forming a continuous enclosed fluid passage between said flexible sheet and said rigid carrier, said fluid passage extending from said inlet orifice, along said inlet channel, through said first concave indentation, along said transfer chanced, through said second concave indentation and along said outlet channel to said outlet orifice; and (c) a flexible membrane, welded in said second indentation sealingly around said access hole, so that said fluid passage is entirely sealed except at said inlet and outlet orifices.

14. A disposable cassette as is Claim 13 further comprising at least one support projection formed from said concave inlet channel positioned adjacent to said inlet valve so that said flexible sheet welded along the perimeter thereof is held away from said concave inlet channel without blocking said fluid path except when said inlet valve is actuated to close said fluid path.

15. A disposable cassette as in Claim 13 further comprising:
(a) a first support projection projecting from said concave inlet channel and positioned adjacent to said inlet orifice and adjacent said inlet valve;
(b) a second support projection projecting from said concave inlet channel and positioned adjacent to said first concave pump indentation and adjacent to said inlet valve, so that said flexible sheet is held away from said channel without blocking said fluid path except when said inlet valve is actuated to close said fluid path.

16. A disposable cassette as in Claim 13 further comprising a flexible support tube having relatively greater resiliency than said flexible sheet and interposed between said inlet channel and said flexible sheet so that said flexible sheet is resiliently held away from said inlet channel except when said inlet valve is actuated to close said fluid path.

17. A method of forming a disposable pumping cassette for use in a pumping instrument having pump actuators and smooth radius valve actuators for positive pumping of fluid from a negative head height comprising the steps of:
(a) forming a rigid plastic carrier with a flat surface and a fluid path therealong, including a plurality of pumping chamber indentations and interconnecting fluid channels formed into said flat surface, defining a perimeter edge at said flat surface entirely around said chamber indentations and said interconnecting channels;
(b) forming said interconnecting fluid channels with a smooth radius corresponding to said smooth radius on said valve actuators in said pumping instrument;

(c) forming a flexible plastic sheet sufficiently large to overlap said perimeter edge entirely therearound;
(d) positioning said flexible plastic sheet against said perimeter edge; and (e) RF welding said flexible sheet to said flat surface of said rigid carrier entirely around said perimeter edge so that a fluid-tight seal results therearound and so that weld beads are formed along portions of said perimeter edge but not a positions in said interconnecting fluid channels where said radius valve actuators make contact.

18. A method of forming a disposable pumping cassette as in Claim 17 wherein said method of RF welding comprises the steps of:
(a) holding a flat face of a first die against said PVC sheet;
(b) holding a flat face of a second die against said copolyester rigid carrier;
(c) squeezing a flat surface of said thin, flexible PVC sheet, abutted against a flat surface of said relatively thicker rigid copolyester carrier, between said flat faces of said first and second RF dies;
(d) maintaining said first RF die at a first temperature;
(e) maintaining said second RF die at a second temperature, which is higher than said first temperature;
(f) adjusting a temperature differential between said first and second dies, so that a weld plane is established between said dies in said flexible PVC sheet and said rigid copolyester carrier, along said flat surfaces of said PVC
sheet and said copolyester rigid carrier, which are being squeezed together;
and (g) activating as RF weld signal through said dies and said PVC and said copolyester rigid carrier partially meld and become welded together at said weld plane, established along said abutted surfaces of said PVC sheet and said copolyester rigid carrier.

19. A method of forming a disposable pumping cassette as is Claim 17 wherein the step of RF welding said flexible sheet to said flat surface of said rigid carrier further comprises the steps of:
(a) providing a first welding die for contact with said flexible plastic sheet, positioned adjacent to said perimeter edge of said fluid path of said rigid carrier, said first welding die having a first cavity formed therein at a position corresponding to an area adjacent to said fluid path;
(b) providing a second RF welding die contacting said rigid plastic carrier at a surface opposite to said flat surface in which said flow path and perimeter edge are formed and having a second cavity formed therein at a position corresponding to said area adjacent to said fluid path; and (c) interposing a non-conductive spacer into said first cavity of said first welding die for holding said flexible plastic sheet out in a desired position relative to said rigid carrier during welding.

20. A method of forming a disposable pumping cassette for use in a pumping instrument as is Claim 19 further comprising the step of squeezing said first and second welding dies toward each other and against said plastic sheet and said rigid carrier during welding to a fixed spared apart distance so that said dies do not move together closer than a predetermined distance during welding.