WO1997023165A1

WO1997023165A1 - Retractable lancet

Info

Publication number: WO1997023165A1
Application number: PCT/US1995/016431
Authority: WO
Inventors: Rowland W. Kanner; Terry B. Kehne
Original assignee: Ryder International Corporation
Priority date: 1994-05-25
Filing date: 1995-12-21
Publication date: 1997-07-03
Also published as: US5527334A

Abstract

An actuator mechanism and assembly (10, 200) for sequentially advancing and retracting a lancet needle (12a, 211) includes a housing (16, 216) having an opening (14, 219a) for operating projection of the needle (12a, 211). Two guide tracks (56, 256; 40, 240) are provided within the housing (16, 216) for guiding separate motions of a two-part needle holder structure (18, 218) propelled by a drive spring (34, 234), and the needle (12a, 211) itself is smoothly guided along one of the tracks (56, 256) to advance and thrust the needle (12a, 211) into a tissue penetration position immediately followed by automatic retraction along the same highly accurate linear path (56, 256).

Description

RETRACTABLE LANCET

Background ofthe Invention

This invention relates to lancet devices particularly for medical use to extract a patient's blood sample, and more particularly relates to mechanism for automatic operation of a lancet needle to initially penetrate and thereafter immediately retract the needle from the skin in a blood sampling procedure.

In order to reduce trauma to the patient during blood sampling procedures, automated finger lancet devices have been developed which eliminate the patient's view of both the skin puncture and the lancet needle or blade itself. As described for example in U.S. Patent Nos. 4,539,988; 4,892,097; and 5,212,879, the lancet blade or needle can be housed within a small device which provides a spring-driven mechanism for thrusting and retracting the blade or needle. While such devices obstruct the patient's view, considerable patient discomfort has been experienced with lateral or rotary blade motion. Accordingly, as described for example in U.S. Patent Nos. 4,924,879; 5,196,025; and 5,318,583, lancet devices have been developed which provide improved patient comfort by moving the lancet needle in rapid continuous thrusting and retracting motion along a linear path to eliminate lateral movement.

Lancet devices in accordance with the present invention provide improvement in construction, operation, user comfort, and disposibility as well as handling safety.

Summary ofthe Invention

In accordance with the present invention, an actuator mechanism and assembly for sequentially advancing and retracting a lancet needle includes a housing having an opening for operating projection ofthe needle. Two guide tracks are provided within the housing for guiding separate motions of a two-part needle holder structure propelled by a drive spring, and the needle itself is smoothly guided along one ofthe tracks to advance and thrust the needle into a tissue penetration position immediately followed by automatic retraction along the same highly accurate linear path.

In a preferred embodiment, the two-part needle holder structure is preassembled within the housing and is integrally molded with a first portion carrying the needle in the reversible skin penetration motions guided by the first track, and a second, transmission linkage portion is coupled to the needle holding portion in arrangement which enables the linkage portion to move along the second guide track and induce the reversible motion ofthe needle holding portion along the linear guide track. The linkage portion ofthe needle holding structure has a cam follower with the second track providing cam guidance for the motion of the transmission linkage which is coupled by a living hinge to induce the reversible, linear needle motion. The cam track has a configuration which enables retention of a pre-cocked condition ofthe drive spring and transmission linkage so that only triggering ofthe mechanism is necessary for blood sampling operation ofthe device.

Optionally, single use disposibility ofthe device is insured by permanent retraction ofthe needle and preventing any re-cocking capability ofthe pre-cocked mechanism. Alternatively, a rearrning or re- cocking structure is incorporated to enable re-energizing the drive mechanism and re-operation of the device for repetitive blood sampling with replaceable lancet needles.

Brief Description ofthe Drawings

FIG. 1 is a perspective view of one embodiment ofthe assembled lancet actuator and device in accordance with the present invention;

FIG. 2 is an enlarged, exploded view ofthe assembly shown in FIG. 1;

FIG. 3 is a sectional view along a plane indicated by line 3-3 in FIG. 1;

FIG. 4 is a sectional view along a plane indicated by line 4-4 in FIG. 3;

FIGS. 5-8 are sequential views ofthe operating positions ofthe assembled actuator mechanism shown in FIGS. 1-4;

FIG. 9 is a fragmentary, diagrammatic view of a modified embodiment of needle holder construction ofa lancet device in accordance with the present invention;

FIGS. 10-13 are internal views of a second embodiment of an assembled actuator in accordance with the invention showing sequential views ofthe mechanism in operation;

FIG. 14 is a reduced, internal view ofthe actuator mechanism of FIGS. 10-13 showing a re-cocking structure enabling reusability ofthe actuator; and FIG. 15 is an internal view of a modified embodiment ofthe actuator of FIGS. 10-14 showing a storage receptacle for a replacement lancet needle unit stored therein.

Detailed Description ofthe Preferred Embodiments

Referring to FIGS. 1-3, an embodiment of a lancet actuator assembly in accordance with the present invention is generally designated by reference character 10. The illustrated embodiment of actuator 10 is designed for single-use disposibility and employs a pre-loaded, sterile needle 12 which is automatically thrusted into and immediately retracted through an operating opening 14 in a molded housing 16. In the illustrated embodiment, the metal needle 12 is encapsulated within an integrally molded, plastic lancet needle structure generally designated by reference character 18. In the assembled configuration ofthe actuator assembly 10, the lancet needle structure 18 includes a frangibly removable needle shield 20 which encapsulates the end 12a ofthe needle 12 but can be manually twisted for frangible removal from the preferred rectilinear, needle-holding body 22 ofthe molded structure 18 to expose the sharp, skin-penetrating end 12a ofthe needle 12 immediately prior to the penetration operation of the assembly 10 for blood sampling. As a result, the insert molded lancet needle 12 is fully encapsulated in thermoplastic of sufficiently high melting point so that the conventional molding temperatures sterilize the needle; the encapsulation maintains the sterility to eliminate the need for individual sterile packaging ofthe needle structure 18 prior to assembly in the actuator assembly 10.

Referring again to FIGS. 2 and 3, the integral needle lancet structure 18 includes both the needle holding body portion 22 and an

(operating drive motion) transmission linkage portion generally designated 24 which is joined to the needle-holding portion 22 through an integral, attenuated hinge portion 26 serving as a "live hinge" for articulated operation as more fully described hereinafter. The linkage portion 24 has a generally planar, elongate main body 28 which has a transversely projecting cylindrical spring bearing 30 formed generally on the opposite end ofthe body 28 in relation to the integral hinge 26. The movable end 32 of a torsion drive spring 34 is inserted and secured in the spring bearing 30. The stationery end 36 of he torsion drive spring 34 is anchored by insertion into an anchoring bore 38 formed in the housing portion 16a of the split housing 16.

The housing half 16a has an integrally formed, guiding cam track wall 40 which guides travel of a cam follower pin 44 integrally formed on the main body 28 ofthe needle linkage portion 24 as best shown in FIG. 3. The cam follower pin 44 laterally projects from the opposite face ofthe main body 28 in axial alignment with the cylindrical spring bearing 30 so that the movable spring end 32 extends through the spring bearing 30 into the bored cam pin 44 for particularly balanced stability ofthe bearing force by the drive spring end 32 internally imposed also on the cam follower pin 44, which promotes stabilized guidance ofthe transmission linkage motion as hereinafter described.

As best shown in comparing FIGS. 2 and 5, the cam track wall 40 and slot 42 have a configuration including three general portions 46, 48 and 50. In the assembled actuator 10, prior to use as illustrated in FIG. 5, the cam following pin 44 is lodged against the wall ofthe short, initial cam slot portion 46 which is arranged at approximately right angle relative to the adjoining slot portion 48 so that the slot portion 46 serves as a pre- cocking notch leading to the slot portion 48; the cam following pin 44 is retained in the slot or notch portion 46 by the bearing force ofthe movable spring end 32 from the pre-wound condition ofthe torsion spring 34 imposing transverse, seating force ofthe pin 44 relative to the direction of travel necessary to release the pin 44 from the notch 46 to enter the slot , portion 48.

The "pre-cocked" position ofthe cam following pin 44 cannot be accidentally dislodged from the slot notch 46 by pulling on the exposed twist-off needle shield 20 and is positively locked in the cocked position of FIG. 5 until the actuator 10 is deliberately triggered for blood sampling operation.

The manual trigger structure 52 is integrally molded with the housing half 16a and is pivotally joined by the attenuated hinge portion 51. The trigger structure 52 also includes a ramped barb formation 53 which will catch under the trigger edge 17 ofthe housing after the first inward deflection ofthe trigger structure 52 for blood sampling operation to retain the inwardly deflected position ofthe trigger structure 52 as a visual indicator of use, as shown in FIGS. 6-8, so that the user will not attempt any second blood sampling operation ofthe actuator 10 which will thereafter be discarded.

To operate the lancet assembly 10 for skin penetration with reference to FIGS. 6-8, the frangible, protective shield 20 is removed by twisting from the needle end 12a, and then the housing opening 14 is gently aligned against the target skin. Thereafter, the trigger structure 52 is manually deflected inwardly as indicated by arrow A so that a trigger cam projection 54 presses the end ofthe linkage body 28 and dislodges the cam pin 44 inwardly, against the transverse force ofthe spring end 32 so that the cam pin 44 is released to enter the adjoining cam slot portion 48 along which the expansion force ofthe spring is directed to drive the cam pin through the slot portion 48. With the downward entry of cam pin 44 into the guide slot portion 48, the same downward deflection ofthe linkage body 28 is transmitted through the integral hinge 26 to the needle- holding body portion 22 to initially begin downward displacement guided along a highly linear path. Upper, spaced guide ribs 56 and lower, spaced guide ribs 58 integrally formed with the housing half 16a form a linear guide track for the downward and upward displacement ofthe needle holding body portion 22 and needle end 12a. As the cam pin 44 is driven by the spring 34 through the medial guide slot portion 48 pulling the linkage body 28 therewith, the integral hinge 26 converts the relative pivotal motion to the needle holding body 22 inducing further linear travel thereof through the track ribs 56 and 58 thrusting the needle end 12a through the housing opening 14 with maximum extension therefrom and resulting skin penetration depth as the cam pin 44 reaches the end ofthe medial slot portion 48 at the entry to the succeeding slot portion 50 as shown in FIG. 7.

From the position shown in FIG. 7, continued unwinding force of the spring 34 drives the cam pin 44 through the upwardly inclined cam slot portion 50 which automatically induces, through the integral hinge 26, sequentially continuous reversal in the motion ofthe needle holding body 22 pulled upwardly along the same linear path through the track ribs 56 and 58, so that the needle end 12a is withdrawn from the skin penetration position of FIG. 7. In the position of FIG. 8 the cam following pin 44 reaches the end ofthe guide slot 50, and in the corresponding terminal position, the needle end 12a is retracted from the housing opening 14 for protection against any further danger of subsequent inadvertent skin penetration.

In the illustrated embodiment, the needle end 12a can only project 5 from the housing opening 14 during a single, deliberately triggered blood sampling operation ofthe lancet assembly 10, because the entirely enclosed drive mechanism prevents any re-winding ofthe drive spring 34 so that after a single blood sampling operation, the lancet assembly 10 cannot be re-cocked or reused and will be discarded, effectively o preventing any cross-contamination of sampled blood.

The blood sampling operation is powered by the torsion spring 34 which assures preset drive and fast penetration and retraction ofthe lancet needle end 12a for minimized user discomfort and precise actuation 5 without dependence upon variable manual power. As best shown in FIGS. 2-4, the transmission linkage portion 24 has a laterally projecting spacer 31 which provides for narrow clearance with the internal wall surface of the housing portion 16b to prevent any potential twisting ofthe lancet needle structure 18 by the operating unwinding of he torsion spring 34. o Additional stability is provided by the comparatively wide and flat linkage body portion 28 to promote smooth relatively sliding engagement ofthe spring coil portion 35 thereagainst during the actuator operation.

Referring again to FIGS. 2 and 3, in order to ensure the highly 5 accurate linear path of both thrusting and retracting of the needle holding portion 22, the guide track formed by the spaced guide ribs 56 and 58 is further enclosed by an extended medial guide rib 57 in housing half 16a and the opposing guide rib 59 in housing 16b. Additionally, in order to minimize tracking friction against the guide ribs, the rectilinear needle holding portion 22 has upper and lower sets of facially projecting nibs 60 and 62.

Referring now to FIG. 9, a modified embodiment of an actuator assembly in accordance with the invention is shown in which one ofthe housing halves 116a or 116b can be provided with an internally projecting ledge adjacent the needle projection opening 114 and the frangibly removable needle shield 120, which encapsulates the needle end 112a within the integrally molded needle portion 122 can be provided with a small stop member 121 which abuts the ledge in the assembled and pre- cocked actuator assembly so that the shield 120 cannot be merely pulled through the opening 114, thereby encouraging only a manual twisting on the shield 120 for frangible removal thus discouraging any premature advancing motion ofthe needle end 112a prior to actual needle sampling operation ofthe actuator 10.

Referring now to FIGS. 10-14, a third embodiment of an actuator assembly in accordance with the invention is generally designated by reference character 200. Additional reference characters of the third embodiment generally correspond to similar reference characters and features ofthe first embodiment 10, with the exception that the third actuator embodiment enables reuse ofthe actuator 200. In order to enable reuse, the actuator embodiment 200 accommodates conventional, disposable lancet needle- and support- body units A which are frictionally retained and replaceably inserted within a holder and carriage portion 222 ofthe molded lancet structure 218. In order to enable replacement ofthe lancet needle units L, the actuator 200 has a cap 219 which is snap-fitted over the lancet opening 214 ofthe two split housing portions 216. The cap 219 will be exposed to the blood sample and will consequently be disposable and replaceable with the used lancet unit L. The cap 219 includes an opening 219A through which the needle point 211 of the lancet unit L can project as shown in FIG. 12. The extension ofthe cap 219 determines the length ofthe projection ofthe needle portion 211 therefrom, and therefore also determines the needle penetration depth when the cap 219 is seated on the doner's skin.

FIG. 10 illustrates the condition ofthe actuator 200 fully prepared for operation, in which a fresh lancet unit L is positioned within the holder carriage 222 and the cap 219 is snapped into place. In this actuator embodiment 200, the manual trigger structure 252 is pivotally mounted on a pivot pin 251 projecting from the wall of the housing half 216. The trigger structure 252 integrally includes a finger engagement lever 253, a trigger cam lobe 254 and a re-cocking lobe 255, as more fully described hereinafter.

In operation, the finger lever 253 ofthe trigger structure 252 is manually pivoted counterclockwise from a position shown in FIG. 10 to the position shown in FIG. 11 so that the trigger cam lobe 254 presses the end 229 ofthe linkage body 228 and dislodges the cam pin 244 inwardly, against the traverse force ofthe spring end 232 so that the cam pin 244 is released from the short, cocking slot or notch portion 246 to enter the adjoining cam slot portion 248, as shown in FIG. 11. The force ofthe spring end 232 driving the cam pin 244 through the cam slot portions 246,248 and 250 induces the deflection ofthe linkage body portion 228 which transmits the force for projection and retraction ofthe needle carriage portion 222 and needle point 211 through the guide ribs 256 and 258, sequentially as illustrated in FIGS. 10-13 corresponding to the same operating motions of he embodiment 10 previously described. In addition, however, once the terminally retracted position ofthe needle point 211 as shown in FIG. 13 completes the skin penetration operation, the protective cover 219 can be removed to allow access and removal of the lancet needle unit L for disposal and then replacement by insertion of a new lancet needle unit L for use in a subsequent blood sampling operation and reuse ofthe actuator device 200.

In order to permit such reuse for a subsequent blood sampling operation ofthe actuator 200, the re-cocking lobe 255 ofthe pivotal trigger structure 252 is engagable by the cam pin 244 in its terminal position at the end ofthe cam slot portion 250 as shown in FIG. 13. Thus, in preparation for reuse of the actuator 200, the trigger structure finger lever 253 can be manually pivoted clockwise with corresponding clockwise pivot ofthe cocking lobe 255 to drive the engaged cam pin 244 reversely through the slot portions 250 and 248 with sufficient torque to rewind the bearing spring end 232 ofthe drive spring 234 until the cam pin 244 reversely reenters the cocking slot notch portion 246 thus reversely traversing the operating path of cam pin 244 from the position of FIG. 13 to the position of FIG. 14. The cam pin 244 is thereafter retained in the slot or notch portion 246 by the bearing force ofthe spring end 232 and rewound torsion spring 234 imposing transverse, seating force ofthe pin 44 relative to the direction of travel necessary to once again release the pin 244 from the notch 246 to enter the slot portion 248, thus re-cocking the cam following pin 244 with retention ofthe rewound condition of the torsion drive spring 234, in readiness for reuse in driving a subsequent blood sampling operation ofthe actuator 200. As a result, the manual trigger structure 252 is reversely pivotal in performing trigger release ofthe cam following pin 244 to guide the blood sampling operation ofthe actuator, as well as re-cocking and reenergizing the drive spring by means ofthe cocking lobe 255, for multiple reuse of the actuator 200 with respective lancet needle units.

Referring now to FIG. 15, in a modified embodiment 300, ofthe actuator in accordance with the present invention, the cap 319 has an integrally molded storage receptacle within which a replacement lancet needle unit R can be removably retained. The replacement lancet unit R projects from the receptacle 320 into a storage cavity 317 formed in the split housing 316 when the cap 319 is installed thereon.

While preferred embodiments ofthe present invention are shown and described, it is envisioned that those skilled in the art may devise various modifications and equivalents without departing from the spirit and scope ofthe appended claims.

Claims

The Invention Claimed Is:

1. An actuating assembly (10, 200) for sequentially advancing and retracting a lancet needle (12a, 211) having a housing (16, 216) for containing a lancet needle structure (18, 218) therein and having an opening (14, 219a) for projection therethrough of a needle portion (12a, 211) of the lancet needle structure (18, 218), and Characterized By: a) a first guide track (56, 256) within said housing (16, 216) for guiding reversible motion of said needle portion (12a, 211) to project and retract through said opening (14, 219a); and b) a second guide track (40, 240) within said housing for guiding transmission motion of a linkage portion (24, 228) of said lancet needle structure (18, 218).

2. An actuating assembly according to claim 1, wherein said second guide track (40, 240) includes first (48, 248) and second (50, 250) portions arranged in communication to guide corresponding redirection of said transmission motion therealong.

3. An actuating assembly according to claim 2, in combination with said lancet needle structure (18, 218) including said linkage portion (24, 228) and a needle carriage portion (22, 222) for said needle portion (12a, 211) thereof being coupled to enable said transmission motion of said linkage portion (24, 228) through said first portion (48, 248) of said second track (40, 240) to produce said projecting motion of said needle carriage portion (22, 222) and said needle (12a, 211) portion through said housing opening (14, 119a) and thereafter continued transmission motion of said linkage portion (24,228) through said second portion (50, 250) of said second track (40, 240) to produce retracting motion of said needle carriage portion (22, 222) for withdrawal of said needle portion (12a, 211) through said housing opening (14, 219a).

4. An actuating assembly according to claim 3, further comprising a track following structure (44, 244) formed on said lancet linkage portion (24, 228) and guided by said second guide track (40, 240).

5. An actuating assembly according to claim 1, further comprising drive structure (34, 234) arranged within said housing (16, 216) for propelling said transmission motion of said lancet linkage portion (24, 228).

6. An actuating assembly according to claim 5, further comprising arming structure (252) arranged to enable re-energizing said drive structure (234) for repetitive operations of said actuating assembly.

7. An actuating assembly according to claim 6, wherein said drive structure (234) comprises a drive spring (234) bearing on said lancet linkage portion (228) to propel said transmission motion, and said arming structure (252) comprises re-cocking structure (255) operable to produce reversely directed motion of said linkage portion (228) relative to said transmission motion, in order to re-energize said drive spring (234) and arm said linkage portion (228) for a succeeding transmission motion and operative reuse to advance and retract a successive needle portion (211) of said lancet needle structure (218).

8. An actuating assembly according to claim 7, wherein said re- cocking structure (255) comprises a reverse drive member (255) bearing on said lancet linkage portion (228).

9. An actuating assembly according to claim 8, wherein said reverse drive member (255) is secured to a trigger structure (254) arranged for initiating said transmission motion of said lancet linkage portion (228).

10. An actuating assembly according to claim 9, wherein said trigger structure (254) and said re-cocking structure (255) form respective portions of a pivot structure (252) arranged for reversible pivotal motion governing corresponding reversible direction of said transmission motion of said lancet linkage portion (228) guided by said second guide track (240).

11. A lancet needle structure ( 18, 218) for use in sequentially advancing and retracting a lancet needle (12a, 211) carried thereon Characterized By: a) a needle holding, carriage portion (22, 222) for carrying advancement and retraction of a lancet needle (12a, 211); b) a transmission linkage portion (24, 228) coupled to said carriage portion (22, 222) in arrangement enabling transmission motion of said linkage portion (24, 228) to induce thrusting motion of said needle carriage portion (22, 222); and c) cam structure (44, 244) for guiding motion of said transmission linkage (24, 228) portion along a guide cam (40, 240) in order to produce said induced thrusting motion of said needle carriage portion (22, 222).