US2737812A

US2737812A - Pipette

Info

Publication number: US2737812A
Application number: US294980A
Authority: US
Inventors: Paul O K Haak
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-06-23
Filing date: 1952-06-23
Publication date: 1956-03-13
Anticipated expiration: 1973-03-13

Description

March 13, 1956 p. 0. K. HAAK PIPETTE Filed June 23, 1952 U M w MK m a w L A u a w alth United States Patent 'ce PIPETTE Paul 0. K..Haak, San Francisco, Calif.

Application June 23, 1952, Serial No. 294,980

' Claims. c1. 73-4254 Another object of the invention is to provide a pipette wherein an exact amount of blood is drawn by capillary attraction, and wherein an exact amount of diluting fiuid is also drawn and measured by capillary attraction so as to be evenly mixed with the blood and from which the diluted blood can be safely and easily applied upon the usual slide or counting chamber.

I am aware that some changes may be made in the general arrangements and combinations of the several devices and parts, as well as in the details of the construction thereof without departing from the scope of the present invention as set forth in the following specification, and as defined in the following claims; hence I do not limit my invention to the exact arrangements and combinations of the said device and parts as described in the said specification, nor do,I confine myself to the exact details of the construction of the said parts as illustrated in the accompanying drawings.

With the foregoing and other objects in view, which will be made manifest in the following detailed description, reference is had to the accompanying drawings for the illustrative embodiment of the invention, wherein:

Fig. l is a side viewof my pipette, and,

Fig. 2 is a sectional view of my pipette on an enlarged scale.

In carrying out my invention I form a measuring or induction tube 1 with an outer bent tip 2 projecting to one side of the tube for facilitating the intake of blood and the discharge of diluted blood.

At the other end or top of the induction tube 1 is a bulb or mixing chamber 3. The upper or inner end of the tube 1 has thereon a bent projecting tube 4 which projects generally centrally into the mixing chamber 3 and is bent to one side generally oppositely to the direction in which the intake tip 2 is bent.

A capillary passage 5 extends through the tube 1 from the tip 2 to the end of the projecting tube 4 and ends abruptly at the inner end of the projecting tube 4 without any material change in its cross sectional area which is substantially uniform.

From the top of the mixing chamber 3 extends a drawing tube 6 axially aligned with the induction tube 1. 'In this drawing tube 6 is a drawing chamber 7. A wall 8 on the top of the mixing chamber 3 separates it from the drawing chamber 7. An inner measuring tube 9 projects from this wall 8 into the drawing chamber 7 and is surrounded by the latter. An upper capillary passage 11 2,737,812 Patented Mar. 13, 1956 extends through the separating wall 8 and said projecting tube 9 and ends abruptly at the top of the projecting tube 9 so as to determine the exact amount of diluting fluid drawn into the pipette. A drawing passage 12v extends from the top of the drawing chamber 7 to the upper end of the drawing tube 6. All the

passages

5, 11 and 12 are in alignment.

A pair of cars 13 extend outwardly from opposite sides of the induction tube 1 and are bent upwardly at their tips so as to accommodate holes 14 in a flexible closure strap 16 which latter is plastic so as to be tightly held over the end of the outer tip 2 of the induction tube l'for sealing the fluid in the pipette.

A mixing bead 17 in the mixing chamber 3 is loose but it cannot block the induction capillary passage 5 because the bent inner tip 4 extends well into the mixing chamber 3 and is bent laterally. Thus the bead 17 can never come to rest against the inner end of the capillary passage 5. In operation the tip 2 of the induction tube 1 is touched against or immersed into the emerging drop of blood from finger or ear, and the blood will rise in the capillary passage 5 until it reaches the upper end of the passage 5 at the tip of the inner bent end 4 where it stops because the capillarity stops at the tip of said end 4. This holds an accurately measured quantity of blood. Then the tip 2of'the tube 1 is immersed in a suitable diluting fluid and suction is applied through the drawing tube 12 to draw the diluting fluid through the lower capillary tube 5 into the mixing chamber 3 and begin the drawing of the mixture into the upper capillary passage 9. The mixture will then rise to the top of the upper capillary passage 9 and will stop there because the second passage 9 stops abruptly inside the drawing chamber 7. Thus the amount of diluting fluid is also measured accurately and automatically without the need of visual observation, and a precisely accurate dilution and mixture is accomplished. By stretching the elastic closure strip 16 over the tip 2 and hooking it on the ears 13 the pipette is sealed for transportation for testing the blood. After uncovering the tip again and by touching it upon a slide or counting chamber a suitable drop of the diluted blood can be discharged for testing.

As the blood and diluting fluid are drawn from the lower capillary chamber 5 into the mixing chamber 3 it is prevented from rushing upwardly into the upper passages because the inner bent tip 4 of the induction passage forms a trap in mixing chamber 3 and directs the flow of the solution against the opposite side wall of the mixing chamber 3, and allows the solution to fall downward and rise gradually as it fills said mixing chamber 3. Thus the mixing chamber 3 is filled evenly and free of air bubbles and affords accurate measurement of the solution. The pipette may be shaken at suitable times to cause the bead therein to mix the contents of the mixing chamber 3.

The device is simple, efiicient and accomplishes uniformly accurate results, reducing human errors to a minimum. The forming of air bubbles and pockets is efiectively prevented by the combination of chambers and capillary passages, and are further minimized by the gradual curving or flaring of the chambers toward their top or outlet passages, as shown at the top of the mixing chamber 3 in Fig. 2.

I claim:

1. A pipette comprising a tube, a mixing chamber formed in said tube, said tube containing a capillary intake passage leading into said mixing chamber, a second chamber formed in said tube spaced from the top of the mix ing chamber, a dilution measuring capillary passage between said mixing chamber and said second chamber, and

a projection extended into said second chamber containing a continuation of said dilution measuring passage.

2. A pipette comprising a tube, a mixing chamber formed in said tube, said tube containing a capillary intake passage leading into said mixing chamber, and a capillary dilution measuring passage extending from the top of said mixing chamber, a loose mixing bead in said mixing chamber, and a projection with a laterally bent end extending in continuation of said capillary intake passage and projecting into and being surrounded by said mixing chamber and pointing toward a side of said mixing chamber so as to prevent said mixing bead from stopping said capillary intake passage.

3. A pipette comprising a tube, a mixing chamber formed in said tube, said tube containing a capillary intake passage leading into said mixing chamber, a second chamber formed in said tube spaced from the top of the mixing chamber, and a projection having a dilution measuring capillary passage projecting into and being surrounded by said second chamber.

4. A pipette comprising a tube, a mixing chamber formed in said tube, said tube containing a capillary intake passage leading into said mixing chamber, a second chamber in said tube spaced above from the top of said mixing chamber, and said tube containing a capillary dilution measuring passage extending from the top of said mixing chamber to said second chamber, a laterally bent tubular projection surrounding the end of said capillary intake passage and projecting into and being surrounded by said mixing chamber and pointing toward a side of said mixing chamber, and a tubular projection around the end of said dilution measuring capillary passage projecting into and being surrounded by said second chamber.

5. In a pipette, an intake tube having capillary passage therethrough, a mixing chamber at the end of the intake tube, a mixing bead loosely positioned in said mixing chamber, a projection extended from the bottom of the mixing chamber inwardly of the chamber and bent at an angle to the axis of said tube pointing toward a side of said mixing chamber and having a capillary passage therethrough in continuation of said passage in the tube to conduct liquid into the mixing chamber laterally and to prevent obstruction of flow by said mixing bead, and an intake end on said tube being bent generally oppositely to the direction of the discharge from said projection.

References Cited in the file of this patent UNITED STATES PATENTS 553,044 Sharples Jan. 14, 1896 694,530 Comer Mar. 4, 1902 1,433,075 Gottlieb Oct. 24, 1922 1,594,370 Kubota Aug. 3, 1926 1,678,540 Trenner July 24, 1928 1,791,829 McCrackan Feb. 10, 1931 2,104,325 Juifa Jan. 4, 1938 2,158,102 Betzold et al May 16, 1939 2,638,787 Flaig et al May 19, 1953 OTHER REFERENCES Fisher Catalog 90 Modern Lab. Appliances, Fisher Scientific Co. N. Y. (1942 catalog.)

Claims

1. A PIPETTE COMPRISING A TUBE, A MIXING CHAMBER FORMED IN SAID TUBE, SAID TUBE CONTAINING A CAPILLARY INTAKE