Method of providing for blood count and pipette and assembly for use therein

July 24, 1962

METHOD OF

Filed March 13, 1958

H· W. GERARDE 3,045,494

PROVIDING FOR BLOOD COUNT AND PIPETTE AND ASSEMBLY FOR USE THEREIN

Sheets-Sheet 1

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FIG. 2

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INVENTOR.

BY

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July 24, 1962 h. _w gerarde

METHOD OF PROVIDING FOR BLOOD COUNT AND

Filed March 13, 1958

AND ASSEMBLY FOR USE THEREIN

3,045,494

PIPETTE

Sheets-Sheet 2

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July 24, 1962 , -----METHOD OF PROVIDING FOr’bLOOd AND ASSEMBLY FOR USE

Filed March 13, 1958

H. W^GERARDE 3,045,494

COUNT ANU PIPETTE THEREIN

Sheets-Sheet 3

FIG. 10

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FIG. 11

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FIG. 12

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BY

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'erraeMEys

United States Patent Office

3,045,494

Patented July 24, 1962

3,045,494

METHOD OF PROVIDING FOR BLOOD COUNT AND PIPETTE AND ASSEMBLY FOR USE THEREIN

Horace WiJIiam Gerarde, 508 Dorian Court, Westfield, N.J.

Filed Mar. 13,1958, Ser. No. 721,139 13 Claims. (Cl. 73—425.6)

This invention relates to a novel method of providing for a blood count and also provides a structurally and functionally improved pipette and assembly for use in the practice of that method.

This application is a continuation-in-part of my prior United States application for patent entitled “Disposable Pipette Assembly,” bearing Serial No. 642,583 and filed on February 26, 1957, now abandoned.

_ It is a primary object of the invention to furnish a pipette and assembly which, because of their improved functional accuracy, low cost, and simplicity and efficiency of operation, will encourage the greater use of blood counting and similar laboratory techniques for diagnostic purposes.

By means of the present teachings a structure is furnished which may be produced at nominal cost. Therefore the assembly may have a “one-time” use, after which it is discarded. Accordingly, the danger of infection to the user, as existing with the use of conventional pipettes and assemblies, is avoided. This is in addition to the fact that the structure will not require cleaning after use and may be employed by technicians who need not be as highly skilled and trained as has heretofore been required where conventional pipettes and assemblies have been used.

With these and other objects in mind, reference is had to the attached sheets of drawings illustrating practical embodiments of the invention and in which:

FIG. 1 is a perspective view of a pipette assembly;

FIG. 2 is a partly sectional and fragmentary view of the assembly as shown in FIG. 1;

FIG. 3 is a fragmentary sectional. view showing an alternative structure which may be employed;

FIGS. 4 to 9 inclusive are somewhat schematic and partly sectional views illustrative of the steps followed in utilizing one form of pipette assembly embracing the present teachings;

FIG. 10 is a fragmentary sectional side view of an alternative form of assembly and showing the same with the parts in one position;

FIG. 11 is a similar view, but showing the parts in a different position;

FIG. 12 is a partly sectional and fragmentary view illustrative of a further form of assembly; and

FIG. 13 is a similar view of still another form of such assembly.

Referring primarily to FIGS. 1 and 2, in which a preferred form of pipette assembly has been shown, the numeral 15 indicates the capillary tube, the inner end of which is mounted by a sleeve 16, in turn connected to a reservoir and actuating unit 17. Tube 15 provides the pipette proper. While it may be produced by employing a proper plastic material of the resin type, it is preferred that it be manufactured of glass. Sleeve 16 may be formed of a resin, although other materials could be employed. Reservoir 17 should be compressible to vary its internal volume. It should be formed of a plastic such as trifluorchloroethylene or vinydene chloride co-polymer, both of which will hold diluent for long periods of time without loss. Also, both may be used in sufficiently thin gauge so that the reservoir body will embrace flexible and resilient characteristics.

The forward end of sleeve 16 preferably defines a tip embracing a base portion 18 and a reduced flange or collar 19 included as part of its end wall. The bore of the collar has a diameter such that it properly receives the inner end of the pipette or capillary tube 15, which is secured in this position in any desired manner and has its adjacent end terminating in the zone of the collar and wall. A sheath 20, as indicated in dotted lines in FIG; 1, may enclose tube 15 to protect the latter and bear against the surface of tip portion 18, from which it may readily be separated when the assembly is to be used.

The rear end of sleeve 16 terminates in a reduced flange 21 which is received within the bore of collar 22 formed at the forward end of reservoir 17. A manipulating member or part is conveniently mounted by sleeve 16 and may take the form of an integral tab 23' to which a label 23 may be suitably attached. This label presents a surface to receive proper indicia, which may include, for example, the date, specimen number, the patient’s name, etc. A volume of diluent 24 of a type corresponding to the count to be performed and proportioned to the volume of pipette tube 15 is disposed within reservoir 17. Also extending into the reservoir interior is the head portion 25 of a mixing bead provided with a plug or stem 26.

That stem has a diameter such that it extends into the bore of sleeve 16 to seal the latter. The area of head 25 is preferably greater than the bore defined by collar 22. Therefore, with the parts in the positions shown in FIGS. 1 and 2, the diluent body 24 within the reservoir will not pass into the bore of sleeve 16 or other parts of the assembly. Should the sleeve be detached from the reservoir 17, then the bead will be retained by the latter and will drop into its interior upon the reservoir being shifted to an upright position.

If it were desired to form the reservoir of glass, this of course could readily be done by employing a structure of the general character shown in FIG. 3. In that view the numeral 27 indicates the wall of such a glass reservoir. In common with reservoir 17, it will contain a body of diluent 28. In order to provide for conditions of pressure above and below atmospheric, body 27 may at its rear end define a neck 28. To the latter there is applied a bulb 29 conveniently formed of rubber. It is apparent that by compressing this bulb and then allowing it to expand, an effect is accomplished corresponding to that achieved by compressing reservoir 17 and then allowing it to expand. If a construction such as is illustrated in FIG. 3 is employed, then, of course, the forward end of the reservoir 27 may have attached to it a sleeve such as 16, formed of plastic or other elected material, and in turn carrying a label or tag 23 of, for example, paper, and mounting a capillary pipette tube, preferably of glass.

Such a tube will have a bore surface which is completely clean. The thin wall of the pipette is provided by drawing a clean tube of larger bore in a flame. When reduced to proper size, the tube is cut by cleavage, after the tube surface has been scratched with a diamond or Carborundum wheel. In this manner the outer end surface of the pipette is perfectly clean, involving as it does cleavage of crystalline material. The outside diameter of tube 15 should be less than the area of a drop of blood into which its outer end is to be dipped or with which that end is to be placed in contact. Therefore, the tube may involve an outside diameter of .036 with a plus or minus factor on the order of .001. The bore diameter, according to the present teaching, should preferably be on the order of .0285 with a plus or minus factor of .0004.

This will provide a pipette involving a capillary tube in which the capacity of the latter is in direct proportion to its length. An ideal length, based on the foregoing measurements, would be one in which .013 cc. with a

3,045,494 plus or minus factor of .0002 cc. is provided for. The diluent within the reservoir or container might vary, of course, according to the type of liquid which is to receive analysis. However, in the case of blood, for which the present apparatus is primarily designed, the volume of diluent, in connection with erythrocyte (red cell) count would involve 2.609 cc. with a plus or minus variation of .031 cc., while in the case of leukocyte (white cell) count the volume of diluent would be .2609 cc. with a plus or minus factor on the order of .0031 cc. The diluent solutions contemplated would in the case of red cells, preferably involve:

Distilled water_________________________ml 200.0

Sodium chloride________________________gm__1.0

Sodium sulfate_________________________gm__5.0

Mercuric chloride_______________________gm__0.5

In connection with the determination of a whitecell count, 1 percent of hydrochloric acid in water will ordinarily be employed.

While, as afore brought out, in assemblies employed respectively for red and white cell counts the capacity of the capillary tubes might be identical while the volume of diluent in the reservoirs of those assemblies were different, the reverse might be true. In other words, for a red cell count the accepted proportion of blood to diluent is 1 part of the former of 200 parts of the latter. In the case of a white cell count, 1 part of blood is employed to 200 parts of diluent. Under these circumstances it is feasible to employ capillary tubes differing in volume by either length and/or bore diameter. In the case of a red cell count, the volume of the capillary tube could conveniently be .013 cc., while in the case of a white cell count the volume of the capillary tube could be .0013 cc.

Where the capillary tube embodies glass, it has been found that it is so light that even if dropped on a relatively hard surface, it will not shatter. Whether it be made of glass or of a suitable plastic, ordinarily its outside diameter should not substantially exceed 1 mm. Where the volumes of the capillary tubes are different for red and white cell counts, then, of course, the same size reservoirs may be used in the different assemblies. Likewise, the same volume of diluent may be contained in each reservoir.

According to the present concept, the blood will rise in the capillary tube to completely fill the bore of the latter. The rate of penetration, penetrating power or penerating pressure of liquids such as blood into capillary tubes is dependent on the surface tensiond and the advancing contact angle of the liquid. Any increase in the contact angle is to be avoided. With the bore surface of the capillary tube being completely clean, no film on that surface will be formed. It has been found that films which are only one molecule thick may profoundly alter the properties of the bore surface. By providing a tube the outer end of which is defined by a thin wall, a sharp edge is present which reduces or eliminates the contact angle, with resultant increased adhesion tension or wetting power. The surface of this edge, being formed by cleavage of the tube, has a crystalline structure that is different from the outer and inner wall surfaces of that tube. This edge surface approaches being the cleanest and most perfect surface attainable by cleavage of a single crystal. The contact angle of a liquid such as water with this surface is as close to zero as can be. Thus, while it is feasible in assemblies as herein taught to provide capillary tubes of materials other than glass, it is definitely preferred to utilize glass tubing produced in the manner afore outlined.

Assuming that an apparatus of the type shown in FIGS. 1 and 2 is to be employed, the physician or technician will, for example, lance the tip of the patient’s finger, so that (FIG. 4) a drop 30 of blood appears on the surface of that finger. Reservoir 17 will be held in at least an upwardly inclined position and sleeve 16 detached therefrom. In such detachment the bead will, of course, drop into the interior of the reservoir. The sleeve, together with the pipette tube 15 mounted thereby, may now be grasped, or if a tab 23' be associated therewith, the latter may be gripped to furnish a manipulating unit. In any event, by maintaining tube 15 at an angle slightly inclined upwardly from the horizontal, its outer end may be brought into contact with the surface of drop 30. As indicated in FIG. 4A, the contact angle of the blood with the bore surface 31 of the tube 15 will approach zero. Also, the end area of the tube will be less than the area of the blood drop. The blood therefore rises in the tube to fill the latter completely by capillary attraction, because the adhesive force between the glass surface of this bore and the blood is greater than the cohesive force of the blood molecules themselves.. Accordingly, the column of blood will extend throughout the entire length of the bore 31 and terminate at its upper or inner end in line with the edge of tube 15. This column will remain intact under all circumstances, so that it is unnecessary to resort to procedures as heretofore practiced to prevent a portion of the column being accidentally displaced from the bore.

Therefore, as shown in FIG. 5, the outer end of the capillary tube may be introduced into the reservoir 17. At the time of that introduction the walls of the reservoir will be partially compressed, as also illustrated in FIG. 5. As sleeve 16 is brought into sealing engagement with the bore surface of collar 22, the pressure upon the side walls is released, as illustrated in FIG. 6. Accordingly, an aspirating action occurs which serves to draw the entire liquid column within tube 15 into the body of diluent within the reservoir. To scavenge substantially all traces of blood from the bore surface, the reservoir may now again be compressed, as in FIG. 7. This will force diluent up through the bore of the tube and into the sleeve 16. With the release of this compressive action, the displaced liquid is again drawn into the reservoir.

Now, as shown in FIG. 8, the sleeve is unseated from the reservoir and reversed, so that tube 15 extends outwardly. The reservoir is shaken, so that the mixing bead will be agitated within the solution contained in the reservoir. This will assure an even dispersion of blood throughout the body of the solution. When this has been achieved, and as shown in FIG. 9, a desired volume of the solution may be discharged, for example, upon a counting chamber 32, to which a glass 33 had been applied in accordance with conventional techniques.

Thus, in the assembly as described, the pipette tube 15 collects and measures blood accurately in a single automatic operation, which is instantly initiated simply by touching the tip of the capillary to the drop of blood. The assembly collects and measures the blood, since the latter is drawn into the tube bore by capillary action and is measured by the length of the tube. Accordingly, unerring physical forces and factors are substituted for the human judgment, skill and experience required to carry out the same operation with conventional equipment. The blood and diluent are not drawn into the tube by mouth. The required volumes are definitely achieved, rather than by relying on the technician attempting to line up the meniscus at the top of a liquid column with a mark on the outside of the tube. Therefore, there is eliminated one of the principal sources of human error inherent in collecting and measuring blood and diluent with the equipment generally used for the purpose at the present time. The blood is collected rapidly and accurately by a quickly performed operation involving the drawing of the blood out of the capillary tube into the reservoir. The latter contains a precisely predetermined and measured volume of diluent. All operations are carried out with the use of the hands and without the necessity of visually determining proper volumes requiring individual calibration of the tube.

(1,046

With conventional pipette techniques, it is extremely difficult to control the rate of flow and size of the drop forming at the tip. Employing the present thin-walled capillary tube, the operator or technician has precise, positive control of the flow of diluted blood from the 5 reservoir to the tip of the capillary, as illustrated in FIG. 9. Diluted blood is forced out of the reservoir by simply applying pressure to the walls of the latter, rather than by allowing the solution to flow out under the influence of gravity. It is apparent that if a construction such as 10 that illustrated in FIG. 3 is employed in lieu of that shown in FIGS. 1 and 2, the same desirable results are achieved. This is also true of the structures shown in FIGS. 10 to 13 inclusive.

In connection with FIG. 12, the numeral 34 indicates 15 a reservoir corresponding to reservoir 17 and containing a predetermined volume of diluent 35. Within this reservoir a mixing bead 36 of suitable configuration is disposed. The forward end of the reservoir is defined by a wall through which a passage 37 extends. That passage 20 is initially closed by a stopper portion 38 formed in the base portion of an adaptor and mounting member involving- a cylindrical body 39 preferably formed with an outstanding flange 4® at the end opposite reservoir 34. This adaptor serves to mount the base portion of a lancet 41, 25 the point of which extends beyond the adaptor. Also, it serves to support a sleeve 42 corresponding to sleeve 16 and also supporting the inner end of a capillary tube 43 corresponding to tube 15.

Thus, the physician or technician is provided in the 30 assembly of FIG. 12 with an instrument such that the drop of blood may be created without resorting to an element foreign to the assembly. The user will simply dismount the adaptor 39 from the reservoir 34, while maintaining the latter in an upright position so that dil- 35 uent does not flow outwardly through the bore 37. Now, by detaching sleeve 42 from the adaptor, the piercing point of the lancet is available for pricking the finger or other epidermis surface of the patient. To this end the adaptor itself may serve as a manipulating element for 40 projecting and retracting the sterile lancet point with respect to the surface to be pierced. The adaptor may now be discarded. Thereupon, the technique as afore traversed may be followed in detail in order to provide the diluted solution for blood count purposes. 45

In certain instances it may be desired to furnish an assembly in which the diluent will be sealed against contamination or escape except when parts of the assembly are destroyed. Such a design is illustrated in. FIG. 13, in which the numeral 44 indicates the reservoir, which 50 corresponds to reservoir 17 and contains a body of diluent 45. Also, this reservoir preferably contains a mixing bead or element 47. The forward end wall 48 of the reservoir maintains the interior of the same isolated. The outer face of end wall 48 is provided with a recess the 55 base Of which defines a diaphragm portion 49. This recess has a diameter such that the rear end of a sleeve 50, corresponding, to sleeve 16, will be accommmodated and retained therein by frictional contact of the surfaces. The sleeve in turn supports a capillary tube 51 corre- 60 spending to tube 15.

When a device such as this is to be used, then the operator will simply grip sleeve 50 and force the same toward the reservoir. The edge of that sleeve will be sufficiently sharp to assure a rupturing of diaphragm por- 65 tion 49. It will of course be understood that the material of the sleeve 50 should also be sufficiently hard to assure the desired penetration. When this result has been obtained, then the procedure as heretofore outlined will be followed. 70

Finally, considering the device as illustrated in FIGS. 10 and 11, the, numeral 52 indicates a reservoir preferably formed of plastic material so as to be compressible. The body of the reservoir is closed at one end by a wall 53 having a bore or opening, while at the other end it is 75

494 closed by a wall provided with an opening which may be defined by a tubular tip 54. The reservoir contains a body of diluent 55 related to the volume of blood or other liquid provided by the bore of the capillary tube forming a part of the assembly. A mixing bead 56 may be disposed within the reservoir 52. An actuator, preferably in the form of a tube of plastic material, as indicated at 57, extends through the opening in wall 53. At its inner end it serves to mount the adjacent end of a capillary tube 58 corresponding to the tube 15.

The device will come to the physician or technician in the condition shown in FIG. 10. Tube 58 may be housed by a sheath (not shown). Likewise, tube 57 may be suitably protected or sealed. The finger of the patient will be lanced, and the outer end of capillary tube 58 will be brought into engagement with the resulting drop of blood by inclining tube 58 in an upward direction, as illustrated in FIG. 4A. Under these circumstances the bore of tube 58 will automatically draw a volume of blood upwardly by capillary action until the bore of that tube is filled.

Thus, a predetermined volume of blood is collected which is the desired quantity when related to the volume of diluent 55. By virtue of the sleeve furnished by the inner end of tube 57, the column of blood will not pass beyond the inner end of tube 58. Using tube 57 as a manipulating element, tube 58 is retracted to a point where it is wholly contained within reservoir 52, as shown in FIG. 11.

The walls of that reservoir ate. now compressed, as indicated in dotted and dash lines in the latter figure. The bore defined by tip 54 is sealed by, for example, placing the operator’s finger in contact with the edge of that tip. Now, upon releasing the pressure upon the walls of reservoir 52, an aspirating action occurs such that the column of blood within tube 58 is drawn into the interior of the reservoir. If desired, a scavening action may be effected by simply maintaining the seal on tip 54, bringing the reservoir to an upright position where the tube 57 extends upwardly therefrom, and thereupon compressing and releasing reservoir 52 a number of times. Under these circumstances the solution will pass into and even beyond the bore of tube 58 and then be lowered to where the column is entirely discharged within the interior of the reservoir.

Now, by agitating the assembly, bead 56 assures an even dispersion of the blood throughout the solution. By inclining the reservoir so that tip 54 extends downwardly, a pressure on its walls will serve to dispense desired amounts of solution onto a receiving surface such as a counting chamber.

In common with the other devices and portions of the assemblies as shown in preceding views, the entire apparatus may be discarded after a single use. No cleaning of the parts will therefore be necessary after a final amount of solution has been dispensed. While the present apparatus is intended primarily for use in connection with blood counts, it is apparent that it will also· be useful in connection with analytical work involving liquids other than blood.

Thus, among others, the several objects of the invention as specifically aforenoted are achieved. Obviously, numerous changes in construction may be resorted to and the steps of the method may be varied without departing from the spirit of the invention as defined by the claims.