Apparatus For Obtaining A Percutaneous And Digital Blood Sample

Abstract

Apparatus for automatically obtaining a percutaneous and digital blood sample in conjunction with a blood collector device having a resiliently crushable mouthpiece housing a pair of incisor lancets, the apparatus including a mounting for the collector device, clamping means for holding the tip of a finger on the crushable mouthpiece, a mechanism for striking the collector device in the mounting to drive the lancets into the finger, and means for massaging the finger to cause blood to flow out of the resulting incisions.

Description

This invention relates to apparatus for obtaining a percutaneous and digital blood sample.

A percutaneous and digital blood sample can be obtained as follows: once the finger has been disinfected, its skin is pricked by means of a stylet to a depth of about 2 to 3 mm.; this causes a first drop of blood to appear that contains a relatively substantial quantity of liquid originating from the subcutaneous cells and which is eliminated by swabbing it with, for example, cotton wool. The pricked finger is then massaged towards the incision to urge further drops of blood to appear and these further drops are collected in a test tube or a capillary, or are sucked into a tube open at both ends.

The different stages of taking a blood sample are generally carried out by specialist personnel although some of these stages, in particular the preliminary preparation of the finger to be pricked, could quite readily be carried out by the subject himself.

An object of the invention is to automate the various operations that are involved in the taking of a percutaneous and digital blood sample in such a way that the subject from whom the sample is to be taken can himself take this sample, practically without the intervention of trained personnel.

According to the invention there is provided apparatus for obtaining a percutaneous and digital blood sample in conjunction with a blood collector device which comprises a tube in the mouth of which is fitted a resilient funnel member fitted with at least one incisor lancet directed towards the open end of the funnel member, said apparatus comprising a mounting formed with a through passage in which said tube can be removably inserted up to said funnel member to support the blood collector device, said through passage having a length less than the length of said tube whereby the inner end portion of the tube will project out of the rear end of said through passage when said funnel member comes into contact with the mounting adjacent the front end of said through passage; a striker mechanism having a releasable striking member facing the rear end of said through passage and adapted to strike, when released, the inner end portion of the tube, when the latter is inserted in said through passage, thereby to tend to propel said tube out of said through passage so that when a portion of the finger from which a blood sample is to be taken is placed on the funnel member at the open end thereof, said resilient funnel member is caused to deform to allow said lancet to be driven into the finger to effect a percutaneous incision therein; a clamping finger holder; and means for periodically varying the clamping action of said holder whereby at least part of the tissues of a finger in said holder may alternately be constricted and released.

In the accompanying diagrammatic drawings:

FIG. 1 is a perspective transparent view showing the main component parts of one constructional of apparatus according to the invention;

FIGS. 2 to 9 are sections taken across the middle of the apparatus shown in FIG. 1, showing the various positions occupied by the component parts of this apparatus in the course of a blood sampling operation;

FIG. 10 is a diagram of the electric control circuit of the apparatus shown in FIG. 1;

FIGS. 11 and 12 are sectional elevations of a blood collector device that can be used with the FIG. 1 apparatus; and

FIGS. 13 to 16 show, in sectional elevation, various stages in the operation of a modified detail of the FIG. 1 constructional form of apparatus.

The apparatus shown in FIGS. 1 to 9 comprises a casing 1 having a base 2, formed by a rectangular plate, and a covering body 3 removably mounted on the base 2. The base 2 and the body 3 are preferably made of a synthetic plastics material.

The body 3 is formed in its front wall with a circular opening 3a (FIG. 2) through which projects a pushbutton 4; in its rear wall with a rectangular cutout 3b which extends over the entire height of the rear wall to accommodate a block 5 secured to the base 2; and in its top wall with a pair of rectilinear parallel slots 3c which extend from the upper edge of the cutout 3b towards the front, with a first, circular, opening 3d located in front of the slots 3c, a second, rectangular, window 3e through which projects a block 6, and with another pair of rectilinear parallel slots 3f which are located between the opening 3e and the front wall and which are in alignment with the slots 3c.

Block 5 has pivotally mounted on the upper portion thereof, at 7, a shackle 8 having a hollow portion 8a of U cross section in which is secured, as by adhesive, a pad of synthetic sponge 9. In the region of pivot 7, the shackle 8 is formed with a pair of parallel lugs 8b coplanar with the limbs of portion 8a and connected to one another by a pin 8c (FIG. 1). One of the lugs 8b has secured to the outside thereof a stud 8d adapted to actuate a switch 10, mounted on the base 2 beside block 5, when the shackle 8 reaches a predetermined angular position upon being swung clockwise about pivot 7, as will be explained in greater detail further on.

The spacing between lugs 8b is equal to that between the slots 3c and their thickness is slightly less than the width of these slots so that they may move freely therethrough when the shackle 8 is swung backwards and forwards as for example between the positions shown in FIG. 2 and in FIG. 4.

On the pivot 7 is mounted a spring 11 having a downwardly projecting arm on which the pin 8c can come to bear whenever the shackle 8 is moved clockwise into the position shown in FIG. 3 and beyond (FIGS. 4 to 6).

At the end remote from the pivot 7, the shackle 8 is extended by a pair of parallel arms 8e coplanar with the limbs of the central portion 8a and having a slightly arcuate outline centered on pivot 7. The distance between the center line of each arm 8e and the axis of pivot 7 is substantially equal to the distance between this axis and the middle of each slot 3f. Moreover, the spacing between the arms 8e is equal to that between the slots 3f whereas their width and their thickness are slightly less than the length and the width of these slots so that when the shackle 8 is swung clockwise or forward, for example to the position shown in FIG. 4, its arms 8e may pass freely into the slots 3f, over their entire length if need be. The outer edges of the arms 8e are moreover each formed with a series of saw teeth 8f.

In front of the block 5 is provided a mounting 12 having a transverse portion at the top thereof and a pair of legs which are secured to the base 2 and which are formed with a pair of upwardly extending slots 12a wherein are slidably mounted the end portions of a pin 13 subjected to the action of a pair of tension springs 14 on the outside of the mounting 12 and secured at their top ends to a pair of studs 12b.

The transverse portion of the mounting 12, which lies beneath the opening 3d in the casing body, is formed with several passages, i.e., a first passage, 12c, which extends generally upwardly though the middle of the transverse portion and which lies opposite the opening 3d ; a second passage, 12d, which extends horizontally through part of the transverse portion between the passage 12c and the front face of the mounting 12; and third and fourth passages, 12e (FIG. 1) and 12f (FIG. 2), which extend horizontally and coaxially from the passage 12c to the opposite side faces of the mounting 12, passages 12e and 12f lying at a level slightly higher than passage 12d and at right angles to the latter.

Passage 12c is adapted slidably to receive a tube forming part of a blood collector device 15 which will be described in greater detail later with reference to FIG. 11; the length of passage 12c is less than that of the tube. Passage 12d has slidably mounted therein an actuating element for controlling a switch 16 which is mounted on the front face of the mounting 12 and the utility of which will become apparent later. Passage 12e serves to house a photoelectric cell C (FIG. 10) and passage 12f serves to house an electric bulb A (FIG. 10) for illuminating the cell C.

Between the legs of the mounting 12 there is pivotally mounted a lever 17 on a pin 18 whose end portions extend into the legs. The lever 17 is made of a material having a relatively high specific weight, e.g. brass or copper, and rests on the sliding pin 13. At its free end, the lever 17 is formed with an upwardly turned portion 17a in the tip of which is formed a groove 17b parallel to its pivotal axis. The width of the lever 17 is less than the spacing between the lugs 8b of shackle 8 to allow relative movement between these parts.

It should be noted that the position of the mounting 12 on the base 2 is so chosen that the mean vertical plane of the mounting, along which the cross sections of FIGS. 2 to 9 have been made, is also the mean plane of the shackle 8. Further, the length of the springs 14, the length of lever 17 and the position of the pivotal pin 18 are such that when the shackle 8 is swung clockwise or forwards in the direction of arrow F (FIG. 2), the pin 8c, in the course of its circular motion, comes into engagement with the lever 17, in particular with its upwardly turned portion 17a (FIG. 2), and the circular path traveled by the tip of this portion 17a, when lever 17 is moved anticlockwise by the pin 8c in the direction of arrow F.sub.1 against the action of springs 14, moves away from that traveled by the pin 8c before the latter comes into contact with the block 5 and in particular reaches the bottom of a notch 5a formed in this block (FIG. 3).

Thus, if the shackle 8 is swung in the direction F (FIG. 2), the springs 14 are caused to tension as soon as the pin 8c comes into contact with lever 17 and this tensioning action will continue until the circular paths traveled by the pin 8c and by the tip of lever portion 17a cease to intersect one another, i.e. shortly after the pin 8c has entered into the retaining groove 17b formed along the tip of lever portion 17a.

If the swinging motion of the shackle 8 is continued in the direction of arrow F, the pin 8c moves out of the groove 17c and altogether disengages the lever 17 so that the latter, through being released, finds itself suddenly subjected to the sole action of the tensioned springs 14 which cause it to swing abruptly in a direction opposite to that of F.sub.1 , i.e. towards the passage 12c in the mounting 12 thereby to strike the base of the blood collecting tube of device 15 (FIG. 4). The effect of this striking action will be described further on.

The illustrated apparatus comprises, as already stated, a block 6 which projects through an opening 3e formed in the top wall of the casing body 3. This block 6 is formed in its upper surface with a V-shaped recess 6a and is fixed to a lever 19 mounted on an eccentric (not shown) driven by the output shaft 20 a powered by an electric motor M via a speed reducing gear of which one wheel can be seen at 20 in the drawings. The lever 19 is formed with an abutment 19a adapted to engage one end of a lever 21 carrying the armature 22 of a relay having a winding 23 and a magnetic circuit 24. The lever 21 is pivotally mounted at 21a on a further lever 25 which is in turn pivotally mounted at 25a on a block 26 secured to a platform 27 which also supports the motor M and which in turn rests on the base 2 of the apparatus via a socle 28. Through the top end of lever 25 extends a stem 29 in which is formed a notch 29a extending along its entire length thereby to form a sufficiently sharp catch to engage with the teeth 8f along the front edges of the arms 8e of shackle 8 when the latter has been swung down (FIGS. 4 to 6).

A spring 30 which is secured at one end to the block 26 and which bears near its opposite end on the stem 29 serves to keep the latter in a position of engagement. The magnetic circuit 24 and its winding 23 are mounted in the opening of a supporting frame 31 to one side of which are provided a pair of projecting lugs 31a by means of which the frame 31 can be mounted on lever 25, the lugs being secured to the opposite faces of lever 25.

The block 26 is formed with a horizontal passage 26a through which extends a slidable pin 26b whose ends contact the lever 25 and the pushbutton 4 respectively. Thus, by pressing on the button 4 in the direction of arrow F.sub.3, the lever 25 can be made to rotate in the direction of arrow F.sub.2 about its pivotal axis 25a and against the action of the spring 30.

As for lever 21, it can occupy either of two positions depending on whether or not the relay winding 23 is energized. In the position which corresponds to the unenergized state of the winding 23 and which is that shown for instance in FIGS. 1 and 2, lever 21 comes to bear under the action of its own weight on a pin 21b secured to the casing of motor M, so that the projection 19a on lever 19 cannot come into contact with lever 21, whatever may be the position occupied by lever 19 in the course of its eccentric motion. But upon energization of the winding 23, the field that is set up by the magnetic core 24 causes the armature 22 to be attracted thereby causing lever 21 to be rocked about its pivotal axis 21a into a raised position (FIGS. 6 and 7) in which its tip comes to lie in the path of travel of the projection 19a. Upon this projection coming into engagement with lever 21 (FIG. 7), the latter is tipped up thereby causing the whole unit that is made up of the lever 21, the frame 31 that carries the winding 23 and its core 24, the lever 25 and the notched stem 29, to be rocked about pin 25a in the direction of arrow F.sub.2. Thus if the shackle 8 happens to be at that time in its lowered position with its teeth 8f in meshing engagement with the notched stem 29, then the latter will be made to disengage from these teeth thus causing the shackle 8 to be subjected to the sole action of its spring 11 and hence to be swung upwards in a direction opposite to arrow F (FIG. 2).

A similar result can be achieved by pressing on the pushbutton 4 in the direction of arrow F.sub.3, since in so doing pin 26b is caused to slide from right to left in the passage 26a to rock lever 25 in the direction of arrow F, this being the direction required to disengage the notched stem 29 from the teeth 8f.

The motor M, the lamp A and the winding 23 are supplied with electric current by means of a circuit which is diagrammatically illustrated by FIG. 10. In this FIG. are also to be found the switches 10 and 16, here referenced 10* and 16*, the photoelectric cell C, the magnetic core 24 of winding 23, and the pushbutton 4, here referenced 4*. The positional relationship of elements 4, 10, 23 and 24 does not in this Figure correspond in any way to reality but their functional representation is however correct. Thus, upon lever 21 being attracted by the winding 23, the shackle 8 is released from the stem 29 and swings upwards under the action of the spring 11 causing the stud 8d to open the switch 10.

The same result can be achieved, as already stated, by actuating the pushbutton 4, and this explains why there is shown a pushbutton 4* acting directly on the movable contact of a switch 10*.

Moreover, because the shackle 8 is the member that governs the closure of the switch 10, its function has here been symbolized by an arrow 8*.

As shown in FIG. 10, the electric circuit of the apparatus, which is supplied with current by a source S consisting of a series of cells housed in a casing S.sub.1 (FIG. 1) secured to the base plate 2, comprises an amplifier which includes a pair of NPN-type transistors, T.sub.1 and T.sub.2 , a pair of PNP-type transistors, T.sub.3 and T.sub.4, and a resistor R.sub.2, this amplifier being controlled by the photoelectric cell C and serving to ensure energization of the winding 23 upon receipt of a suitable signal from the cell C.

It should here be pointed out that the cell C and the source of illumination A serve to determine when the transparent or translucent tubular body of the collector device 15 has been filled with a sufficient quantity of blood, the cell producing signals which are different when receiving a light beam of full intensity from source A or a light beam of lesser intensity, as when the blood that has collected in the tube has reached the level of the light beam issuing from source A. It should however be noted that the supply of current to the light source A, which takes place through a resistor R.sub.1, only occurs when the switches 10 and 16 are closed, i.e. only when the shackle 8 has been swung into its lowered position (FIG. 4) and when a blood collector device 15 has been inserted into the passage 12c of the mounting 12. The same applies to the motor M which can only be supplied with current when these switches have been closed.

Thus, upon the blood being collected in the tube of device 15 reaching the level of the light beam projected by the source A towards the photoelectric cell C, the switch 10 will be made to open the motor M will hence be made to stop.

The amplifier, consisting of transistors T.sub.1 to T.sub.4 and of resistor R.sub.2, and the resistor R.sub.1 are housed in a casing B mounted on the platform 27.

Before describing the operation of the illustrated apparatus, a few particulars will be given about a preferred form of blood collector device that can be used in conjunction with the apparatus for taking and collecting a blood sample (FIG. 11).

This device comprises a tubular body 32 of transparent or translucent material, for example polyethylene, in the mouth of which is engaged a plug 33 constituting the lower, discharge, part of a funnel member 34 having a cuplike portion 35 of resilient plastics material. The cup 35 rests on the rim of the mouth of the tubular body 32 by means of an annulus 35a provided at the base of the cup 35. The wall of the cup 35 and the plug 33 are formed with an L-shaped groove 36 forming a passage which allows the air contained in the tubular body 32 to escape as the latter is being filled with liquid, in particular blood.

At the lower end of plug 33 there projects a capillary cannula 37 extending nearly to the bottom of the body 32, coaxial with said body and forming an extension of an axial passage in the plug 33. The plug 33 and the cannula 37 form an integral unit made of synthetic resin.

At the bottom of the cup 35 is provided an annular groove 35b in which is held the peripheral part of a circular metal plate 38, for example of stainless steel, which is provided with two triangular lancets 38a and 38b extending perpendicularly to the plate 38, on opposite sides of a slot 39 in said plate.

Above the plate 38 in the cup 35 is arranged an annular pad 40 of absorbent material, e.g. blotting paper, impaled on and held in position by the lancets 38a and 38b. As shown, the slot 39 and the opening in the pad 40 lie opposite one another and are in alignment with the central passage in plug 33.

The part of the lancets 38a and 38b that projects above the pad 40 has a length of at least 2 to 3 mm.; these lancets may extend further but not beyond the level of the upper rim of cup 35.

It is these lancets 38a and 38b which are intended to form the cutaneous incisions that have to be made for taking a blood sample, as will now be seen.

The apparatus described with reference to FIGS. 1 to 9 operates as follows:

When the shackle 8 is in its raised position shown in FIGS. 1 and 2, a blood collector device 15 is inserted through the opening 3d in the casing body 3, and into the passage 12c of mounting 12 until the funnel member of the device 15 comes to rest on the mounting 12 at which point the lower end portion of its tubular body will project into the space lying between the legs of the mounting 12, as shown in FIG. 3.

Once the subject's finger from which a blood sample is to be taken has been duly cleaned and disinfected with dilute alcohol, at least over the fleshy part of the top joint (underneath the nail), the subject lays his hand on the apparatus casing 1 and places the tip of his disinfected finger on the mouth of the cup formed by the funnel member of device 15, and places the middle joint and the adjoining part of the top joint of this finger in the V-shaped recess 6a that is provided in the block 6.

The shackle is then moved in the direction of arrow F to bring it into the position shown in FIG. 4. Once the shackle has traveled through a certain angular distance, the pin 8c comes into engagement with the top surface of the lever portion 17a to depress the lever 17 and hence to tension the springs 14. When the pin 8c reaches the groove 17b along the tip of the lever portion 17a the arms 8a of the shackle start to extend through the slots 3f in the casing body 3 without however yet being in a position where the teeth 8f can begin to come into meshing engagement with the notched stem 29 (FIG. 3). It is in this position of the shackle 8 that the pin 8c begins to bear on the spring 11.

With the shackle 8 being moved further down, the pin 8c moves out of the groove 17b and slips off the cocked lever 17 thereby triggering off the latter to strike, under the action of the springs 14, the base of the tubular body 32 of the blood collector device 15 (FIG. 4). The device 15 cannot, as a unit, rise beyond the point where the subject's finger is resting on the top of its funnel member 34, but because the walls of the cup 35 are collapsible, in view of the fact that the funnel member 34 is made of resilient material, and because the tubular body 32 is slidingly mounted in the passage 12c of mounting 12, the tubular body 32 can nonetheless be made to move upwards under the percussive action of the striking lever 17 to drive the lancets 38a and 38b into the flesh of the finger (FIG. 12) to a depth corresponding to the length of the projecting portions of the lancets, thereby making the desired incisions in the epidermis and the dermis.

Once lever 17 has imparted all its kinetic energy to the blood collector device, it ceases to exert any force on the latter and drops back on to the sliding pin 13. Thus, once the desired incisions have been made, the tubular body 32 will be forced back to its initial position under the action of the deformed elastic walls of the cup 35 tending to resume their normal uncollapsed position (FIG. 11), and the lancets 38a and 38b will be withdrawn from the incisions they have made although remaining in close proximity to the latter.

While the striking action is taking place, the shackle 8 will have reached the position shown in FIG. 4. In this position the pad 9 has come to bear on the top of the first and second finger joints, the notched stem 29 has come into engagement with the teeth 8f provided along the shackle arms 8e, and the stud 8d has caused the switch 10 to close so that the control circuit for the apparatus may supply electric current to the motor M, the lamp A and the cell C.

In this position of the shackle 8 also the finger finds itself tightly held between the block 6, along the bottom, the pad-lined shackle portion 8a, along the top, and the limbs of the shackle portion 8a, along the sides, the grip exerted on the finger being variable, in particular in the plane of FIG. 4. The variable gripping action exerted by the finger-holding arrangement is due to the fact that the block 6 is movably mounted and is eccentrically driven by the motor M in the direction of arrow f (FIG. 4) since in the course of this eccentric motion, the block 6 is made to move to and from in relation to the incised tip of the finger and is also made to move upwards as it moves towards the incised finger tip and to move downwards as it moves away from the incised finger tip.

The finger thus finds itself being periodically subjected to a kind of massaging action from back to front by compression of the part of the finger that lies on the block 6, and this massaging action causes the blood flowing to this part of the finger to be urged towards the incisions so as to issue therefrom in the form of drops which are collected in the cup of the funnel member of device 15.

It is to be noted that the first few drops of blood thus collected in the cup contain a high proportion of physiological liquid which originates from the subcutaneous cells lying near the incisions and which is clearly undesirable in the blood sample. That is why there is provided at the bottom of the funnel member cup 35 an absorbent pad 40 which will soak up these few drops of impure blood and it is only when the pad 40 has been sufficiently impregnated with a mixture of physiological liquid and blood, that the clean blood then issuing from the finger will begin to flow into the tubular body 32. In this connection it is to be noted that the lancets considerably facilitate this flow because, although removed from the epidermis, they remain directly opposite the incisions they have made and are at a sufficiently short distance from them to enable the drops of blood issuing from the incisions to fall on and be ruptured by the tips of the lancets, whereupon they will flow rapidly over the surface of the latter into the outlet opening of the funnel member 34. The lancets thus play the part of effective collectors preventing the formation of a thick blood dispersion in the cup 35.

When the level of the blood that has accumulated in the tubular body of the collector device 15 has reached a sufficiently high level to interrupt or interfere with the light beam directed to the cell C, the latter causes the relay winding 23 to be energized, as already described, thereby to move the lever 21 to its raised position (FIG. 6) and hence to release the shackle 8 from engagement by the notched stem 29 whereby the shackle 8 may move to the position shown in FIG. 7. The switch 10 is, as a result, opened so that the motor M and the lamp A cease to be supplied with electric current. The massaging action of the finger then stops and since the latter is no longer gripped in the holding means formed by the shackle 8 and the block 6, the subject can remove his hand from the apparatus.

As can be seen from FIGS. 3 to 7, the blood collector device 15 is so positioned in the apparatus that it would be particularly difficult for it be extracted from the latter by hand, once full. That is why the extraction operation is here done, at least partially, in a mechanical manner. This is achieved by lifting the shackle 8 into the position shown in FIG. 8 since, in doing so, the pin 8c comes to bear on the underface of the lever portion 17a and progressively comes to lift lever 17 which in turn gradually lifts the blood collector device out of the casing body 3, until such time as the lever 17 abuts against the underside of the transverse portion of the mounting 12.

It will be observed that the underface of lever portion 17a has a rounded outline, that the center of curvature of this rounded outline comes to coincide substantially with the pivotal axis 7 of the shackle 8 when the shackle 8 reaches the FIG. 8 position, and that radius of this rounded outline is slightly greater than the distance between the pivotal axis 7 and the oppositely facing surface of the pin 8c. Consequently, when the lever 17 is in the FIG. 8 position, there is nothing to prevent the shackle 8 from being swung back further to the position shown in FIG. 9, this being the same position as the starting position shown in FIG. 2, and once the pin 8c has been raised to a level higher than the tip of lever portion 17a, the lever 17 will drop back on to the sliding pin 13, and the apparatus is then ready for a fresh blood sampling operation.

FIGS. 13 to 16 illustrate a modified constructional form of finger holder. This holder, which also serves to maintain a finger by its tip on a blood collector device and to massage the finger whereby blood is made to flow towards the incisions made in the finger tip, comprises a stirruplike member 41 whose limbs extend through slots (not shown) into the casing 42 of the apparatus where they are pivotally mounted on a pin 43 eccentrically driven by the output shaft 44 of a motor (not shown), and further comprises a swell 45 which is provided on the top surface of the casing 42 between the limbs of the stirruplike member 41 and on which the subject from whom a blood sample has to be taken is meant to put one of his fingers. Underneath the top of member 41 there is provided a pad 46 of synthetic sponge via which member 41 comes to bear on the finger.

The manner in which the finger is massaged as illustrated by FIGS. 13 to 16 wherein the stirruplike member 41 is shown occupying four different positions as a result of the shaft 44 having been rotated each time through 90.degree. in relation to the previous position.

The illustrated apparatus has of course only been given by way of example and a number of other constructional forms could be envisaged. For instance, instead of being portable, as described, and being run off batteries, the apparatus could be designed to be normally static and be adapted to be supplied with electricity off the mains.

Also, different constructional forms of blood collector devices can be used in the illustrated form of apparatus and a number of such devices, in addition to that illustrated in FIG. 11, have been described and illustrated in our copending Pat. application Ser. No. 843096, filed July 18, 1960, entitled "Blood Collector Device."

Claims

We claim:

1. An apparatus for obtaining a percutaneous and digital blood sample from a human finger in conjunction with a blood collector device comprising a tube in the mouth of which is fitted a resilient funnel member fitted with at least one incisor lancet directed towards the open end of the funnel member, said apparatus comprising a housing, a mounting in said housing, said mounting formed with a through passage in which a tube can be removably inserted, said through passage having a predetermined length and a top and bottom opening; a striker mechanism mounted in said housing and having a releasable striking member facing the bottom opening of said through passage, means for releasing said striking member to propel it toward said bottom opening, said striker member adapted to strike, when released, the inner end portion of a tube, in said through passage, thereby to tend to propel a tube out of said through passage; a clamping means mounted on said housing and adapted to clamp a finger on said housing in line with said top opening of said through passage and means for periodically varying the clamping action of said clamping means whereby at least part of the tissues of a finger in said holder may alternately be constructed and released.

2. Apparatus as claimed in claim 1, wherein said clamping means comprises a supporting block adapted to support a human finger and a movable shackle adapted to be applied on to the part of a finger opposite to that which is meant to lie on said block, a lever, a motor, an eccentric on said motor, said lever drivingly connected at its one end to said motor through the intermediary of said eccentric and connected at its opposite end to said block, wherein said motor is adapted to rotate in a direction such that said block may be caused to move from the back of a finger towards the front thereof while at the same time compressing the tissues of the finger, and wherein the plane in which the eccentric motion of the block-carrying lever takes place contains the axis of said through passage, the relative positions of said through passage and of said block being such that the bottom opening of said through passage opens in a mean plane substantially equidistant from points, along the eccentric path followed by the block, respectively corresponding to maximum and minimum compression of the finger tissues when a finger is placed on said apparatus.

3. Apparatus as claimed in claim 2, wherein said shackle comprises a lever which is mounted for pivotal movement in said housing in the plane of eccentric motion of said block-carrying lever and at a location opposite to that occupied by said block in relation to said through passage, said shackle being movable between a first extreme position in which it is adapted to be applied to a finger and a second extreme position which is sufficiently far removed from the first to provide free access to said block and to the funnel member of a blood collector device when inserted in said through passage, said apparatus further comprising a means for locking said shackle in said first extreme position and a return member for moving said shackle away from said first position upon being released from the action of said locking means.

4. Apparatus as claimed in claim 3, including first and second switches and an element on said shackle wherein said motor is supplied with current through at least said first switch adapted to be closed by said element carried by said shackle when said shackle is moved towards said first extreme position, and through at least said second switch controlled by an element adapted to be actuated by a blood collector device when inserted in said through passage to close said second switch.

5. Apparatus as claimed in claim 4, and further comprising a light source arranged to project a beam of light across said through passage, a photoelectric detector located opposite said source in relation to said through passage to receive said beam after crossing said through passage, a photoelectric detector located opposite said source in relation to said through passage to receive said beam after crossing said through passage, electronic amplifying means controlled by said detector, a relay having a winding armature and core and controlled by said amplifier to actuate said locking means into releasing said shackle, the arrangement being such that when, during operation, the blood accumulating in a tube reaches a level such that it interferes with the light beam directed towards said detector, said locking means releases said shackle whereby said return member may move said shackle away from said first extreme position to open said first switch and hence stop the motor.

6. Apparatus as claimed in claim 5, wherein the free end of said shackle is provided with at least one arm having a saw-toothed longitudinal edge comprising teeth and said locking means comprises a lever which is mounted for pivotal movement between first and second end positions, a return member, said lever having a stem, said lever adapted to be subjected to the action of said return member tending to hold it in said first position and said stem adapted to come into meshing engagement with said teeth on said arm when said lever is in said first end position and said shackle has been moved to said first extreme position, said second end position being such that said stem cannot come into meshing engagement with said teeth on said arm when said lever is in said first end position and said shackle has been moved to said first extreme position, said second end position being such that said stem cannot come into meshing engagement with said teeth, and wherein the lever of said means carries the winding and the core of said relay and further carries the armature of said relay for pivotal movement between a first angular position remote from said core, which it occupies when said winding is not energized, and a second angular position in contact with said core, which it occupies when said winding has been energized, said apparatus further comprising a cam associated with said block-carrying lever, which is so positioned as to come into contact with one end of the relay armature, when said relay has been energized, and which is adapted to move said armature in a direction such as to cause the lever of said mechanism to be rocked into its second end position.

7. Apparatus as claimed in claim 6, and further comprising a manually actuatable push button cooperating with the lever of said locking means and adapted, when pressed, to rock said lever into its second end position against the action of the return member associated therewith.

8. Apparatus as claimed in claim 6 wherein said mounting lies between said block and the pivotal axis of said shackle and is formed with a pair of limbs, and wherein said striking member includes a rocking lever which extends between said limbs, which is pivotally mounted to the side of said mounting furthest from the pivotal axis of said shackle, and which has a projecting free end portion to the side of said mounting nearest the pivotal axis of said shackle, a spring means, said rocking lever freely resting in an inoperative position on a support which is subjected to the action of said spring means tending to return said lever to said inoperative position when it has been moved away therefrom in the direction of the base of said limbs, and wherein the striking lever has a length such that, upon being rocked, the path traveled by the tip of its free end portion may intersect the circular path traveled by an actuating member associated with said shackle when said shackle is about to reach said first extreme position, so that, upon said armature being pivoted from its second extreme position to its first extreme position, said shackle will cock said striking member against the action of said spring means, said cocking action lasting for as long as the respective circular paths traveled by the tip of said free end portion and by said actuating member intersect one another, said striking member being released from the action of said actuating member as soon as these paths cease to intersect one another and then being subjected to the sole action of said spring means which thus propel it towards the bottom opening of said through passage in said mounting.

9. Apparatus as claimed in claim 8, wherein said free end portion has a rounded surface whose center of curvature coincides with the pivotal axis of said shackle when said striking member has been moved into an intermediate position lying between said inoperative position and a position adjacent the rear end of said through passage, the radius of said curvature being slightly greater than the distance between the pivotal axis of said shackle and the portion of said actuating member farthest from said axis.

10. Apparatus as claimed in claim 1, wherein said finger holder comprises a stationary block for supporting the fleshy part of a finger, and a U-shaped shackle having limbs straddling said block on opposite sides thereof and a transverse portion adapted to engage the topside of a finger, said shackle being movable in a plane which is parallel to its limbs and which contains the axis of said through passage, a motor and eccentric and said shackle being drivingly connected to said motor through the intermediary of said eccentric underneath said block whereby it may exert on a finger a pressure during that part of its motion when said eccentric moves away from block and to relax said pressure when said eccentric moves towards said block, the direction of rotation of said motor being such that said shackle is caused to move from the back of a finger towards the front during that part of its motion when it exerts on a finger a compression.

11. An apparatus as claimed in claim 1 wherein said clamping means comprises a finger-supporting block and a movable shackle adapted to be applied onto the part of a finger opposite to that which is meant to lie on said block, a motor mounted in said housing and an eccentric, a lever drivingly connected at its opposite end to said motor through said eccentric, said block being mounted on one end of said lever wherein said motor is adapted to rotate in a direction such that said block is caused to move from the back of a finger clamped in said clamping means towards the front thereof while at the same time compressing the tissues of the finger, and wherein the plane in which the eccentric motion of the block-carrying lever takes place contains the axis of a tube when it is in the said through passage, the relative positions of a tube and of said block when a tube is in said mounting means being such that the rear portion of the tube is adapted to open in a mean plane substantially equidistant from points, along the eccentric path followed by the block, respectively corresponding to maximum and minimum compression of the finger tissues.

12. An apparatus as in claim 1 wherein said clamping means is associated with said means for releasing said striker member whereby said striker means is released when a finger is clamped in place on said housing.