US2994349A - Pipette control device - Google Patents

Description

Aug. 1, 1961 DEMOS 2,994,349

PIPETTE CONTROL DEVICE Filed Oct. 29, 1957 2 Sheets-Sheet l Suction INVENTOR. y 7PTE T DEMOS W M ATTORNEKS g- 1961 P. T. DEMOS PIPETTE CONTROL DEVICE 2 Sheets-Sheet 2 Filed 001:. 29, 1957 INVENTOR. By PEER T: DEMOS ATTORNEYJ %United States Patent Ofiice Patented Aug. 1, 1961 Filed Oct. 29, 1957, Ser. No. 693,199 2 4 Claims. (Cl. 14121) The present invention relates to control devices for pipettes and similar apparatus.

While numerous automatic or mechanical pipetting de vices have been evolved for assisting in facilitating the fwithdrawing of measured quantities of fluids and the like and delivering the same in predetermined amounts, such as one or more drops at a time, the industrial and research chemists, biologists and others still rely heavily upon simple pipette tubes to one end of which the opera- ;tor applies his mouth to draw fluid into the tube, and to the same end of which he then applies a finger to release the fluid in the required number of droplets. The speed with which the researcher, for example, must often accomplish numerous pipetting operations, the requirement that only one hand be occupied with the pipetting, the irreplaceable measure of control aflorded by finger-release ,of the fluid within the pipette, have all been factors in ,causing the rejection in many cases of automatic or aux- Eiliary apparatus.

: The use of the mouth-and-finger technique, however, is lsubject to great dangers when radio-active liquids or gother poisonous substances are employed. Despite these dangers, a great number of operators persist in using this ancient technique, relying upon their skill to minimize accidents.

An object of the present invention, accordingly, is to provide a. new and improved control device for a pipette and the like that shall permit the operator to retain the mouth operation and finger control, but without any of the above-mentioned dangers, and that shall do so without requiring more than the use of a single hand and with substantially the same operational movements thereof presently employed in ordinary mouth-and-finger-control pipetting. In summary, this end is achieved by providing a protective chamber having a suction inlet, a pipette inlet and an opening into which a finger may be inserted to control the pipette inlet. Preferred details are later described.

A further object is to provide a novel pipette control 'device that may also be employed with more elaborate equipment, if desired.

Other and further objects will be explained hereinafter and will be more particularly pointed out in the appended claims.

The invention will now be described in connection with the accompanying drawing, FIG. 1, of which is a perspective view of the invention in its most elementary form;

FIG. 2 is a side elevation of the same;

FIGS. 3 and 7 are fragmentary views, similar to FIG. 1, of modifications;

FIG. 4 is a view, similar to FIG. 2, of a further modification;

'FIG. 5 is an end elevation; and

FIG. 6 is a fragmentary side elevation, upon an enlarged scale, of still additional modified pipette control devices.

Referring to FIGS. 1 and 2, a conventional calibrated pipette tube is shown at 1 inserted within a beaker of liquid 3 for the purpose of withdrawing a predetermined quantity of the liquid for subsequent adding, one or moredrops at a time, to another container. The before-mentioned ancient, widely employed technique involves applying suction by the mouth to the upper end 5 of the pipette tube 1 to withdraw approximately a desired quantity of the liquid from the beaker 3 into the tube 1, as at 7. The finger 9 is then applied to the upper end 5 to permit, by releasing and re-applying the finger, the liquid level 7 to drop to the precise desired quantity of liquid, as measured on the pipette calibrations 11. The operator would then, by further intermittent release and reapplication of the finger 9, add the liquid in the pipette 1 to another container, drop by drop, as for the purpose of producing certain chemical effects. The previously described dangers are evident when it is considered that the pipette tube is of small diameter and that a slightly excessive mouth inhalation by the operator will result in potentially dangerous liquids entering the mouth.

This is avoided, in accordance with the invention, by the protective chamber 13, shown for illustrative purposes in the form of a glass or quartz tube closed at the left-hand end 4 and open at the right-hand end 2. The upper end 5 of the pipette tube 1 is inserted into a resiliently gasketed pipette inlet 15. The gasket may, for example, be in the form of an annular grummet 17 having upper and lower lips overlapping the opening 15 in the tube, which opening is preferably, though notessentially, disposed along its lower or bottom surface near the closed end 4 of the chamber 13. A suction inlet 19, preferably, though not essentially, disposed at the top of the container 13, more centrally located therealong, is connected to a mouth piece 21 to which the operators mouth may be applied, just as the operator has heretofore taken the end 5 of the pipette 1 into his mouth to apply suction. The open end 2 of the chamber 13 isof suflicient dimensions, as is the chamber inner dimension, to permit the finger 9 (that heretofore has been applied to the upper end 5 of the pipette 1) to be inserted or received therein to a point where a portion of the finger, shown as the forward part, is juxtaposed to the pipette inlet 51517.

By providing a resilient sealing lining 6, as of rubber and the like, at least in the region of the open end 2 of the chamber 13, the index finger 9 may be sealed within the chamber 13. With the finger raised to an upper position of insertion out of contact with the pipette inlet 5-15-17, the operator applies suction to the mouth piece 21, drawing the liquid 7 into the pipette 1, under the control of the upper surface of the finger 9 cooperatingwith the lower periphery of the inlet 19 in a valving manner. The chamber 13 provides a protective preferably transparent reservoir that would have to be filled before any liquid could even enter the mouth piece'zl, thus entirely safe-guarding the operator. "Upon remov ing the mouth from the mouth piece 21, so as to break the suction, air may be allowed to enter the chamber 13 under the control of the valving action of the upper surface of the finger 9 cooperating with the lower periphery of the inlet 19, as the operator lowers the finger 9 to a lowered position of insertion so that its lower portion covers the pipette inlet 51517 and then, with precisely the same finger movements to which he has long been accustomed, proceeds with the further drop-release operations.

If, moreover, the liquid is not only damaging to the mouth (which danger has now been overcome by the present invention), but, also, to the skin, the operator may use a preferably flexible protective finger sleeve 8, FIG. 1,

which may, if desired, be attached to the resilient sealing may be operated during the application of suction to provide for precise measurement of the quantity of liquid withdrawn into the pipette tube. 7

Where external suction apparatus is to be employed, a mechanical valve means for releasing the suction and applying atmospheric pressure to the chamber 13 by letting air therein, is preferably employed. Such a valve means, in the simple form of a resiliently g'asketed further opening, is shown in FIG. 3 at 10. When the finger 9 is moved to the dotted lower position, the valve opening 10 is closed and suction may be applied at 2.1 as before. When the finger is moved to the solid-line raised position, as in FIGS. 1 and 2, however, the valve is actuated so that the opening 10 communicates the chamber suction inlet 19 with the atmosphere and the suction is relieved or released so that finger-control may be efiective at the pipette inlet -1517.

The valve opening need not be in the lateral forward position of FIG. 3, moreover, but may be in any position where the finger 9 can conveniently cover the same and also move to cover the pipette inlet. Thus, as a furtherillustration, in FIG. 4, the valve opening 10 is shown to the right of the suction inlet 19 and communicating with the upper portion of the index finger 9.

External valve control may also be effected, if desired. In FIG. 5, for example, the lateral valve opening 10 communicates with a closed-ended extension 12 having a small opening 14 in the vicinity of the finger 9' next to the index finger 9. The finger 9' may thus control the valve opening 1014 externally to the chamber 13 and without deviating from the normal position of the pipette operator's hand. To provide a finger rest and a greater measure of stability, asupporting rod 16 may be provided somewhat coextensive with the valve extension 12.

A more complicated mechanical mechanism is illustrated in FIG. 6 wherein upward movement of the index finger 9, shown in solid lines, may operate a plunger valve mechanism 18 in opposition to the biasing action of an attached spring 20, thus to block the air opening 10 but to permit suction to be applied to the chamber 13. Lowering of the finger to the dotted position will release the plunger 18 downward to its dotted-line position, closing ofl? the suction tube 21 by means of the upper portion 18' of the plunger, and opening the air inlet 10 to permit the chamber 13 to become exposed to atmospheric pressure. Other types of valving mechanisms, including etlectrically operated solenoid devices may obviously also be employed.

herein and in the claims. Further modifications will,:'

moreover, occur to those skilled in the art and all such are considered to fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A finger-operable control device for use with a pipette and the like comprising a chamber closed at one end and open at the other end to receive a finger, the chamber being provided with a suction inlet and a pippette inlet the latter of which is disposed to be covered by the finger when in a first position of insertion within the chamber, the said chamber suction inlet being communicable with the atmosphere and having means for enabling valving of the suction inlet by the actuation of the finger when in a second position of insertion within the chamber, such actuation permitting the introduction of air through the suction inlet into the chamber in order to break the suction, and means for sealing the said one end of the chamber about the inserted finger.

2. A finger-operable control device as claimed in claim 1 and in which the said sealing means comprises a resilient lining disposed within the said other end of the said chamber.

3. A finger-operable control device as claimed in claim external to the said suction inlet to the said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 553,044 Sharples Jan. 14, 1869 1 1,092,384 Nickels Apr. 7, 1914 1,791,829 McCrackan Feb. 10, 1931

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