FR2597607A1 - Automatic pipette applicator apparatus - Google Patents

Abstract

The apparatus comprises, on the one hand, a base fitted with vertical pillars on which there is mounted in a sliding manner a framework 80 supporting a row of pipettes 92 adapted to be raised and lowered under the action of a motor 116 and a row of plungers 94 adapted to be raised and lowered in the pipettes 92 under the action of a motor 126 and, on the other hand, a rack carriage 36 which moves longitudinally under the action of a motor 40. The three motors are controlled by a microprocessor. The carriage carries a sample plate 16 equipped with washing 26 and rinsing 28 cuvettes, with a drying space 32 provided with a strip of blotting paper 30, with a row of fluid sample cells 24 and an application space 21 provided on a microporous support 20. Devices for monitoring the relative positions of the carriage, the pipettes 92 and the plungers 94 are provided. The microprocessor receives these position signals as well as operational sequences provided by a stored programme. The function of the apparatus is to wash, rinse and dry the tubes of the pipettes before and after each sampling and application of fluids. Application: analysis of organic liquids by electrophoresis or thin-layer chromatography.

Description

AUTOMATIC PIPETTES APPLICATOR APPARATUS
The present invention relates generally to the application of fluid samples to support strips for analysis. More particularly, the invention relates to an automatic applicator device with pipettes for depositing samples of fluids on a microporous support.

 Such a support, cellulose acetate or agarose strip for example, can then be used for electrophoresis or thin layer chromatography measurements. Electrophoresis is a process of moving charged particles in an electric field applied to a solid or semi-solid medium. This technique is commonly used in medical research and in laboratories, for the analysis of different proteins contained in the blood.

 In the electrophoresis technique, a sample of blood or other organic fluid is applied to a support medium which is then subjected to an electric field in order to separate the components of the sample. The support media used in the electrophoresis processes are of one of the following types: cellulose acetate, agar, agarose or acrylamide gels.

In laboratory work, it is desirable that a plurality of samples be applied to the support medium in such a manner that each of the samples can be subjected at the same time to the electric field.

 The samples can be applied one by one to the support medium using a hand pipette, but such a pipette must be rinsed with a purifying agent and then dried before a new sample is aspirated and then applied to the support medium.

 Applicator devices have been developed for applying simultaneously or in parallel, several samples of fluids to support strips. Such applicators are described on page 61 of the Cénéral Catalog 1984-85 of the company Helena Laboratories of Beaumont, Texas. These applicators can apply eight or twelve samples at the same time to a microporous support medium and, in this way, have the advantage of making the electrophoresis process easier to implement and more reproducible.

 The fluid applicators known to date are essentially non-automatic applicators which require purification of their tips after each application of a sample to the support medium.

 Automatic pipette applicator devices are known, however. For example, a device sold under the brand name "Well Washers" by Bio Tech Instruments Inc. of Burhington, Vermont has an alignment mechanism by which a row of eight or twelve pipette tubes can be positioned above one of a plurality of wash wells. The automation of the device allows a selection of filling volumes, impregnation times and washing cycles.

 As a second example of an automatic device for taking and applying fluid samples, we will endow complementary American patents Nos. 4,478,098 and 4,554,839.

 No known applicator device constitutes an device for automatically filling a plurality of pipettes from the same plurality of cells full of fluids to be analyzed and for then applying the sample of fluid contained in each of the pipettes with precision to a support medium.

 Another disadvantage of the known devices is that they have no means of automatically washing and purifying the pipette tubes during each cycle, so as to avoid contamination of each of these tubes during the application of a new plurality fluid samples to a new support medium.

 Another disadvantage of known applicator devices is that they have no means for automatically and precisely applying a very small quantity of fluid - of the order of a microliter for example - to a support medium.

 Another disadvantage of the known devices is that they do not include any means for precisely diluting a very small quantity of fluid - of the order of a microlite - in a dilution liquid and for precisely applying a very small quantity of l sample thus diluted to a support medium.

 Consequently, a first object of the invention is to provide an automatic pipette applicator apparatus for aspirating samples of fluid contained in a plurality of cells by means of a corresponding plurality of pipettes and for applying these samples in a manner precise to a microporous support medium intended to then be used in electrophoresis or thin layer chromatography.

 Another object of the invention is to provide an automatic applicator device with pipettes which not only sucks and deposits fluid samples on a support medium such as cellulose acetate or agarose but also empties, purifies, rinses and drying the necks of the pipette tubes with a suitable purification fluid before and after each application of a sample of fluid to the support medium.

 Another object of the invention is to provide an automatic applicator device with pipettes by which the movements of the tubes and pistons of the pipettes are controlled so as to apply with precision a very small sample of fluid to a support medium.

 Another object of the invention is to provide an automatic applicator device with pipettes for automatically and precisely diluting a very small quantity of fluid sample with a dilution liquid and for precisely applying a very small quantity of sample thus diluted to a support medium.

 According to the invention, an automatic applicator device with pipettes of the type comprising a base, a sample plate arranged on this base and a subset of pipettes supported above the sample plate by vertical uprights integral with the base. , said subassembly being equipped with a mounting frame adapted to undergo vertical displacements is characterized in that the sample tray comprises a row of liquid sample cells transversely disposed and an application space longitudinally separated from said row cells, adapted to receive a microporous support medium.

 According to another characteristic of the invention, the apparatus comprises horizontal displacement means for causing a longitudinal movement relative to the sub-assembly of pipettes and the sample tray and vertical displacement means for effecting a vertical movement at said mounting frame with respect to said sample plate.

 According to another characteristic of the invention, the apparatus comprises a plurality of pipette tubes removably attached to said mounting frame, the tubes being separated by intervals corresponding to those of said liquid cells, a plurality of micro- pistons engaged in said plurality of pipette tubes is provided and translation means provided for vertically moving the pistons in these tubes.

 According to another characteristic of the invention, signaling means are provided for producing longitudinal displacement signals representative of the relative longitudinal position of the subset of pipettes and of the sample tray, signals of displacement of the mounting frame of the pipettes representative of the relative vertical position of this chassis and of the sample tray and of the piston displacement signals representative of the relative position of the pistons and pipette tubes.

 According to another characteristic of the invention, a programmed digital processor is provided to respond to the longitudinal displacement signals of the pipette subset, to the vertical displacement signals of the pipette mounting frame, to the signals of displacement of the pistons in the pipettes and to generate a sequence of control signals for means for vertical displacement of the pipettes and means for vertical displacement of the pistons in order to draw a predetermined quantity of liquids from the sample cells into the tubes of the pipettes and to apply the liquid samples of the tubes to corresponding points on the microporous support medium when this is placed on the application space of the sample tray.

 One embodiment of the invention comprises a base equipped with a longitudinally disposed slide. A carriage mounted mobile on this slide carries a sample tray placed in a removable manner on this carriage. This tray includes a row of liquid sample cells and an application space longitudinally separated from the row of cells. This application space is suitable for receiving a microporous support medium (such as cellulose acetate or an agarose strip) used in electrophoresis or in thin layer chromatography.

 A subset of pipettes is mounted vertically on the base of the device above the carriage and the sample tray. The subset of pipettes is mounted on two vertical pillars transversely separated from each other fixed to the base of the device. A mounting frame mounted sliding on the pillars is arranged transversely to the sample plate.

 The mounting frame includes a mounting plate fitted with sliding guides mounted on the pillars. A beam carrying pipettes is fixed to this plate. A plurality of microsyringe tubes is arranged in a row on this support beam, the heads of these tubes being mounted fixed on this beam. The tubes of the microsyringes are spaced from one another by intervals corresponding to those of the liquid cells on the sample plate. The tubes are hollow and have a neck at their lower end.

 A piston carrying beam is vertically movably disposed above the pipette carrying beam and a plurality of micro pistons are attached thereto. Each of these micro-pistons is slidably mounted in a pipette tube. A piston displacement control frame carried by the mounting plate is movable vertically relative to. this mounting plate. The piston displacement control frame removably supports the piston carrying beam.

 Translation and signaling means are provided for moving the carriage longitudinally forwards and backwards under the mounting frame and for producing signals indicative of the position of the carriage.

Translation and signaling means are also provided for moving this mounting frame up and down, above the base of the device, and for producing signals indicative of the position of the mounting frame. Translation and signaling means are likewise provided for raising and lowering the beam carrying the pistons relative to the mounting frame and for producing signals indicative of the position of this beam.

 A programmed microprocessor is provided to respond to the position signals of the carriage, the mounting frame and the piston carrying beam and to produce a sequence of control signals selectively intended for the means of translation of the carriage, the mounting frame and the piston carrying beam, in order to suck a first predetermined quantity of liquid from the sample cells into the corresponding pipette tubes, then apply the liquid drawn in each of the pipette tubes to the corresponding locations in the support medium placed on the transverse application space of the sample tray.

 The sample tray includes a wash basin and a discharge basin longitudinally spaced from each other and relative to the sample cells. The programmed microprocessor produces another sequence of control signals for the translating means before aspirating the liquid from the sample cells, in order to draw a second predetermined quantity of rinse liquid from the wash bowl into the tubes of the tubes. different pipettes and then discharge this rinse aid into the discharge bowl.

 The apparatus according to the invention also comprises a sample tray equipped with a drying space adapted to receive a strip of blotting paper transversely disposed. This drying space is longitudinally separated from the row of sample cells, the washing cuvette, the discharge cuvette and the transverse application space. The programmed microprocessor also produces another sequence of control signals for the translating means after rejection of the rinsing liquid into the discharge bowl in order to dry the necks of the pipette tubes on the strips of blotting paper.

 Preferably, the sample tray comprises bosses and lower parts, the row of sample cells and the washing and discharge cuvettes being arranged in the bosses and the transverse application space as well as the space drying, arranged on the lower parts.

 The sample tray can include a row of dilution wells longitudinally spaced from the sample cells.

The programmed microprocessor includes a program, implemented by a dilution signal, to automatically instruct the device to dilute the samples aspirated in the pipette tubes in a dilution liquid, to mix the sample and the liquid dilution in each of the dilution cells before the diluted and mixed fluid sample is applied to the locations provided for this purpose on the support medium.

The objects, the advantages and the characteristics of the invention will become clearer as a result of the following description of an embodiment of the invention made with reference to the appended drawings in which:
Figure I shows a perspective view of an embodiment of an automatic pipette applicator device according to the invention, a sample tray being inserted and the cover installed.

 FIG. 2 is a schematic representation of an apparatus according to the invention showing the functional relationships between the sample tray provided with its sample cells, its washing bowl and its discharge bowl and an application space longitudinal equipped with a microporous support medium, fixed under a subset of pipettes in which individual pipette tubes are moved together up and down and a beam carrying pistons adapted to be mounted and lowered in the tubes of these pipettes.

 FIG. 2A schematically shows another embodiment of the invention in which the mounting frame comprises two fixed units and the subset of pipettes is movable longitudinally relative to this frame.

 Figure 2B is a perspective view of another embodiment of the sample tray comprising a row of dilution wells.

 Figure 3 is a side view with parts removed and / or cut, the cover removed and the view taken along a line 3-3 drawn in Figure 1.

 Figure 4 is a section of the carriage and the sample tray.

 Figure 5 is a top view, taken along a line 5-5 drawn in Figure 1, which shows the section of the base of the apparatus at level 5-5, the slide, the carriage and the sample tray under the pipette subset.

Figure 6 is a sectional view, taken along a line 6-6 drawn in Figure 5, which shows the base, the carriage and the sample tray according to the invention, and, in addition, the translation and guiding means by which the slide is moved forward and backward relative to the subset of the pipettes
Figure 7 is a front view, taken along a line 7-7 drawn in Figure 3, which shows with parts removed and / or cut, the subset of pipettes mounted sliding on pliers integral with the base and comprising a mounting frame which goes up and down relative to the base and carries a row of individual pipette tubes and a movement control frame movable vertically relative to the mounting frame, for vertically moving a piston carrying beam so as to move individual pistons inside the tubes of each pipette.

 Figure 8 shows a top view of the pipette sub-assembly showing the dashed frame for mounting the pipette sub-assembly.

 Figure 9 is a sectional view, taken along a line 9-9 drawn in Figure 7, which shows the relationships between the mounting frame, the beam carrying the pipettes and the beam carrying the pistons and the means through which the mounting frame is moved up or down relative to the base of the device.

 Figure 10 is a view similar to Figure 7, which mounts the mounting frame in a low position, the carrier beam of the pistons remaining in a low position and the pistons being high inside each of the pipette tubes.

 Figure 11 is a top view in section, taken along an Il-Il line drawn in Figure 10, which shows the motor, the rack and the gear system by which the mounting frame is raised and lowered relative to the base.

 Figure 12 is a sectional view, taken along a line 12-12 drawn in Figure 10, showing the relationships between the mounting frame after it has been lowered by the rack and pinion system under the action of the engine running relative to the rack fixed to the mounting frame.

 Figure 13 is a view similar to those of Figures 7 and 10, which shows the piston displacement control frame and the beam of these pistons in the low position relative to the mounting frame, thus forcing the pistons associated with pipettes to s '' push into the tubes of these pipettes and any fluid previously aspirated inside these tubes, to be pushed through the necks of the pipettes and rejected outside.

 Figure 14 is a sectional view, taken along a line 14-14 drawn in Figure 13, which shows the rack-and-gear system by which the piston displacement control frame and the piston carrying beam which is integral, are lowered and mounted relative to the mounting frame.

 Figure 15 is a sectional view, taken along a line 15-15 drawn in Figure 13, which shows the piston control frame in the low position relative to the mounting frame through the action of the rack system -gear controlling the relative movement of the piston control frame and the mounting frame.

 FIG. 16 is a schematic representation of a microprocessor, of the integrated circuit type, receiving signals produced by position detector circuits associated with the carriage, the mounting frame, and the control frame and applying control signals to the motors of movement of the carriage, the mounting frame and the piston control frame.

 FIG. 17 is a functional diagram illustrating the program stored in the microprocessor, for automatically washing, drying, taking and depositing samples of liquid on a strip of support medium.

 According to Figure I which shows a perspective view of an automatic pipette device 10, this device comprises a base 12 on which releasably a sample plate 16. This plate includes a space 21 adapted to receive a medium microporous support 20 such as a cellulose acetate or agarose strip, used in the field of zone electrophoresis or more generally in any field using component separation techniques, thin layer chromatography for example. A cover 14 is moved above the base 12. Through it appears a row of pipettes 18.

 According to Figure 2.qui is a schematic representation of an embodiment of the invention, the main mechanical elements of the device appear, base and cover removed. None of the mounting devices that the apparatus comprises is shown in FIG. 2 so as to simplify the explanation of the functional relationships between the sample plate 16 and the subset of pipettes 70. The means of translation are represented in a functional rather than a real way, the details of these means being described in the figures and the comments below.

 The sample tray 16, as shown, comprises a row of sample cells 24, a washing bowl 26, a rinsing or discharge bowl 28 and a longitudinal space 21 on which a microporous support medium 20 is transversely arranged in a removable manner. The sample cells 24, the rinsing bowl 28 and the washing bowl 26 are arranged in bosses 22 of the sample plate 16. A plastic cup can be placed in each of the cells 24. A drying space 32 placed between the rinsing bowl 28 and the sample cells 24 is placed substantially at the same vertical level 49 as the sample application space 21 on which the support medium 20 is disposed.

 As it appears in FIG. 2, the different zones of the sample tray 16 are longitudinally separated and the transverse intervals which separate the sample cells 24 corresponding to those of the application points 19 on the support medium 20 as well as the tubes 92 of the subset of pipettes 70 are arranged in a row corresponding to that of the sample cells 24. The liquid is sucked from these cells by the automatic fluid sampling device according to the invention and is applied with the same spacers on points 19 of the microporous support medium 20.

 It is advantageous to arrange the sample cells 24, the discharge bowl 28 and the washing cell 26 in the bosses 22 of the sample plate 16. In this way, the mounting frame 80 of the pipette sub-assembly 70 only needs to descend into a single low position, during different washing, discharging, drying, sampling and application operations. However, it is obvious to any person skilled in the art that other arrangements are possible, in particular when different levels of the mounting frame are provided in the translation and signaling devices which control the movements of the mounting frame 80. A detailed discussion of these translation and signaling devices which control the movements of the mounting frame is provided below.

 The schematic representation of FIG. 2 shows that the sample plate 16 is moved back and forth under the subset of pipettes 70 by means of a motor 40 driving a toothed wheel 38 which meshes with a rack 36. When the motor shaft 40 rotates, the sample plate 16 secured to the rack 36 moves forwards and backwards under the subset of the pipettes 70.

 In the subset of the pipettes 70 represented in FIG. 2, a mounting frame 80 is moved upwards and yers downwards by means of a drive motor 116 provided with a toothed wheel 120 meshing with a rack 122 In this way, the entire mounting frame 80 and the pipette tubes 92 fixed on the frame 80, go up and down as a function of the rotation of the drive motor 116 of the frame 80.

Likewise, the pistons 94 fixed to the support beam 90 and a frame 84 for controlling the movement of the pistons go up and down with respect to the mounting frame 80, as a function of the rotation of the motor 126 driving the frame 84 and that of its toothed wheel 130 engaged in the rack 132 secured to the frame 84. By way of illustration, the drive motor 126 for driving the frame 84, its toothed wheel 130 and the rack 132 are shown mounted on the front face of the chassis 80 but in the actual device shown in the figures described below, they are mounted on the rear face of the frame 80 through cutouts provided for this purpose.

 FIG. 2 therefore represents the main elements of the apparatus according to the invention, insofar as the displacements of the plate 16 forward and backward under the pipette tubes 92 are concerned, the displacements in upward and downward movement of the chassis 80 and pipettes 92 and the movements of raising and lowering of the pistons 94, of the carrying beam 90 and of the control frame 84 with respect to the mounting frame 80.

 FIG. 2A schematically represents another embodiment of the invention in which the sample plate remains fixed relative to a base 12 with the sub-assembly of pipettes 70 mounted on rollers 300 in order to allow a longitudinal displacement of it . Figure 2A also shows that the sample tray can have two separate elements, an application tray 16A and a fluid sample tray 16B. The application tray 16A is adapted to removably receive a support medium 20 ', while the fluid tray 16B comprises a row of cells 24', a discharge or rinsing bowl 28 ', a washing 26 'and a drying space 32'. The operation of this other embodiment of the invention is similar to that of the apparatus according to FIG. 2, with the exception of the movement and signaling means provided for moving longitudinally the subset of pipettes 70 'relative to the fluid trays 16B and application 16A. The details concerning these means of movement and signaling will become apparent to a person skilled in the art following the description which follows which relates to similar means of movement and signaling.

 FIG. 2B represents a variant 16 ′ of the sample tray which comprises an additional row of dilution cells 25 in addition to the row of sample cells 24, the discharge cuvette 28, the washing cuvette 26 and drying space 32.

 Figure 3 is a side view, taken along the line 3-3 shown in Figure 1, a portion of the slide 34 being removed to mount its construction. The slides 34 are mounted on feet 48 which are also visible in FIG. 5. The sub-assembly of the pipettes 70 has a rear face 86 and a front face 73. One of the tubes 92 of the sub-assembly of the pipettes is shown in dotted lines in the high position.

A carriage 46 is mounted to slide on a slide 34 as shown in more detail in FIG. 6. Racks 36 are fixed
to the carriage 46 and are movable relative to the base 12 by means of the motor 40 driving the carriage which comprises a toothed wheel 38 meshing with the rack 36.

 Notches are made along the left edge of the carriage 46. These notches cooperate with a displacement switch to provide signals indicative of the longitudinal position of the carriage. The notches 50, 52, 54, 56 and 58 shown in FIG. 3 correspond respectively to the washing bowl 26, to the row of cells 24 and to the application space 21, the notch 57 corresponding to a row of additional dilution cells 25 (see fig. 2B).

 FIG. 4 represents a vertical section made through the carriage 46 and the bracket 16, which shows how the washing bowl 26, the rinsing bowl 28 and a sample cell 24 have been arranged in a boss 22 of the plate 16.

 A drying space 32 and a transverse application space 21 are shown on the plate 16. Blotting paper 30 is placed in the drying space 32, however, that a microporous support medium such as cellulose acetate or of agarose, is placed in the transverse application space 21.

 Figure 5 is a top view, taken along a line 5-5 drawn in Figure I. The carriage 46, shown supported by the slides 34, is movable back and forth by means of the motor 40, the toothed wheel 38 and the rack 36, as is more apparent in FIG. 6. The sample plate 16 is disposed on the bottom 47 of the carriage 46. Notches for signaling positions made on the sides of the carriage 46 cooperate with displacement contactors 60 and 62 fixed to the slides 34.

 Rollers mounted on springs 61 and 63 are applied to the longitudinal edges of the carriage 46 and are pushed into the notches formed in these edges when the carriage passes in front of them. For example, the notches made on the left side of the carriage 46 correspond respectively to the positions of the washing bowl 26, of the rinsing and discharge bowl 28, to the blotting paper 30, to the sample cells 24 and to the points of application of the fluids 19 when these cuvettes, cells, blotter and application points are located directly below the tubes of the pipettes 92.

 When the carriage 46 moves backwards and the washing bowl 26 is located directly below the tubes 92, the roller 61 enters the washing notch 50 thereby activating the contactor 60 which signals to the microprocessor associated with the electronic module 200 (see fig.

3 and 16) that the washing bowl is very precisely placed under the pipette tubes 92. The displacement switch 60 is similarly activated when the roller 61 enters the notches 52, 54, 56, and 58 to indicate that the position of the other elements (cuvettes, cells, application points) is exactly located below the pipette tubes 92.

 On the right side of the carriage 46 appears a notch 59 in which the roller 63 is engaged. A contactor 62 corresponding to the sample plate 16 is thus activated to indicate that the carriage is in its position before rnaxirnale. A displacement switch 65, mounted on the rear edge of the carriage 46, is activated when the rear edge of the plate 16 reaches this position, thereby producing a signal indicating that the plate 16 is correctly positioned on the carriage 46. The stops 64 are adjustable and constitute means for precisely positioning the application points 19 longitudinally below the tubes 92, when the carriage 46 is in its maximum rear position.

 FIG. 5 also shows a start button 214 by means of which the programmed microprocessor receives a signal to start the automatic sequence of the successive operations of the automatic pipette device according to the invention, which will be explained in more detail below. after. The lamp 212 indicates to the user of the apparatus 10 that it is in operation.

 Figure 6 shows in a sectional view, taken along line 6-6 drawn in Figure 5, the means by which the carriage is moved relative to the slides 34. These slides 34 are mounted fixed on the base 12 by means of feet 48. The carriage 46 has lateral grooves 149 in which the slides 34 are engaged.

 The plate 16 rests on the bottom 47 of the carriage 46. The motor 40 for moving the carriage is fixed on the base 12 and comprises a shaft 42 mounted on bearings 44. Toothed wheels 38 integral with the shaft 42 mesh with racks 36 fixed to the carriage 46. Under the action of the motor 40 rotating in one direction or the other under the control of the microprocessor of the electronic module 200 (cf. fig. 16), the carriage 46 moves forward or backward.

 FIG. 7 represents the sub-assembly 70 of the pipettes seen from the rear along a line 7-7 drawn in FIG. 3. The feet 76 of the sub-assembly 70 are shown fixed by nuts to support blocks 78 integral with the side walls of the base 12. On the feet 76 are mounted vertical pillars 72 shown in Figures 7, 10, 13 and in top views 8, II and 14. The front plates 73 and the bottom plate 86 of the sub-assembly 70 are fixed by nuts to the feet 76.

 A mounting frame 80 is slidably mounted on the vertical pillars 72. Holding bearings 74 ensure easy movement of the slides 75 along the pillars 72. The mounting frame 80 is fixedly mounted on the slides 75 by means of nuts 81 With reference to FIGS. 7 and 13, it can be seen that the chassis 80 secured to the slides 75 mounted sliding on vertical pillars 72, can be moved from a high position as shown in FIG. 13.

 A beam 88 carrying the pipette tubes 92 is fixed to the frame 80 by means of nuts 89. On the carrying beam 88 is arranged a row of pipette tubes 92 whose heads 193 are fixedly mounted in the carrying beam 88 as will be explained below. As can be seen in the partial section of the support beam 88, a beam 91 for holding the pipette tubes is provided which holds the lower parts of these tubes and gives them stability in space. The ends 97 of the holding bar 91 are provided with adjustable screws 95 which extend beyond the lower edge of the chassis 80 and which cooperate with the bottom surface 49 of the plate 16 to precisely fix the vertical position of the necks 93 of the pipette tubes 92 relative to the support medium 20 and the blotting paper 30 arranged on the low surfaces of the tray 16. Such an adjustment allows the drops which form at the end of the necks 93 of the pipette tubes, when the pistons 94 are pushed inside these tubes 92, to touch either the support medium or the blotting paper. The drops present on the necks 93 of the tubes 92 are held in place because of their size patite (about one microliter) and the surface tension forces of the necks of the tubes.

When these necks are caused to penetrate slightly into the upper layer of the support medium 20 or blotting paper 30, the drops are released from the surface tension which held them in the tubes and are then applied precisely to the blotting paper or to the medium. support.

 Guides 183 fixed to the frame 80 have grooves in which the frame 84 for controlling the movement of the pistons is inserted so that it can be moved up or down relative to the frame 80. The control frame 84 has the cutouts 85 in which a beam 90 carrying the pistons is engaged. The pistons 94 of the tubes 92 of the pipettes are integral with the carrying beam 90 and are engaged in the tubes 92. In FIG. 7, the pistons 94 are in the extreme high position relative to the tubes 92. The control frame 84 is adapted to descend relative to the chassis 80. This displacement causes the beam 90 carrying the pistons to descend relative to the beam 88 carrying the pipette tubes and the pistons 94 to descend into the tubes 92, thereby forcing any fluid contained in these tubes to exit through the necks 93 of these tubes and form a droplet at the end of these necks.

 Position signals are produced which are indicative of the position of the chassis 80 relative to base 12 and that of the control frame 84 and its pistons 94 relative to the chassis 80. The displacement contactor 106 secured to the chassis 80 cooperates with a low stop 115 mounted on the foot 76 of the sub-assembly 70 to provide an extreme low position signal for the chassis 80 when the latter reaches this position. Similarly, a displacement contactor 105 mounted on the right side of the chassis 80 is adapted to cooperate with a high stop 114. The contactor 105 supplies the microprocessor of the electronic module 200, a signal indicating that the chassis 80 is in the high position extreme.

 The displacement contactor 108 mounted on the guide 83 arranged on the left is adapted to cooperate with the cam 100 of the position for applying the fluid samples and with the cam 102 for washing. The displacement contactor 108 is activated by the application cam 100 and then by the washing cam 102, when the control frame 84 rises relative to the frame 80. The descent cam 104 activates the contactor 110 mounted on the guide 183 disposed on the right, when the control frame 84 reaches its extreme low position, the pistons 94 being completely lowered into the tubes 92 of the pipettes.

 Figure 9 is a sectional view, taken along the line 9-9 shown in Figure 7, which shows the mounting frame 80 and the control frame 84 both in their extreme high position. The chassis 80 was brought into this extreme high position under the action of the motor 116, the toothed wheel 120 and the rack 122 fixed on the bottom plate 86 of the sub-assembly 70.

According to FIG. 10, the sub-assembly 70 formed by the pipettes and their associated elements is represented with the chassis 80 in the low position.
and the piston beam 90 and the pistons 94 in the high position relative to
to the S8 pipette beam. The tubes 92 are lowered into the bowls
wash 26 to suck 5 microliters of fluid, for example.

Figure It is a top view of the sub-assembly 70, taken on
along the line Il-Il drawn in Figure 10, which represents the mechanism
control with which the chassis 80 is raised and lowered relative
at the base 12. A motor 116 is fixed to the chassis 80 by means of a screw
117. The output shaft of the motor 116 includes a pinion 119 meshing with a pinion 120 L mounted on the left end of a shaft
124 fitted with a. identical gear 120 R mounted on its right end.

The shaft 124 is mounted rotating on bearings arranged in supports
118 integral with the chassis 80. Racks 122 fixed on the rear plate 86 of the sub-assembly 70 have their teeth engaged in those of the pinions
120 L and 120 R. When the motor 116 rotates in one or the other direction under the control of the microprocessor, the frame 80 goes up or down with respect to the base 12 and to the rear plate 86 driven by the pinions and the racks. The front view (FIG. 10) of the subset of the pipettes 70 with the chassis 80 in an extreme low position reveals the racks 122. This front view also shows that the stop screws 95 engaged on the ends 97 of the bar holding 91 of the tubes 92, terminate a little above the bottom surface 49 of the plate 16, so that the droplets which form at the end of the necks 93 of the tubes 92 can touch the surface 49 and apply a sample fluid in the support medium or blotting paper.

 Figure 12 is a sectional view of the sub-assembly 70, taken along a line 12-12 drawn in Figure 10, which shows that the motor 116 has turned and driven its pinion 120 so that the frame 80 has been lowered relative to the base 12 and to the boss 22 of the plate 16.

In this way, the tube 92 has been lowered into one of the bowls arranged in the boss 22 of the plate 16. The washing bowl 26 is shown to show the tubes 92 of the pipettes lowered by the frame 80, the fluid being sucked in from the bowl 26 to the tubes 92 under the action of the pistons 94 pulled upwards by the control frame 84. It is clear from FIGS. 11 and 12 that the frame 80 is moved away from or closer to the bosses 22 by the action of the motor 116 driving the pinion 120 to move up and down on the fixed rack 122.

 According to FIG. 13, in the subset 70 of the pipettes, the control frame 84 has been moved down, thus forcing the pistons 94 to sink again into the tubes 92. This has the effect of forcing any fluid previously aspirated into the tubes to be deposited either on the application space, or on blotting paper, or in the discharge bowl.

It can be seen that the displacement contactor 168 has been brought back into a situation such that any upward movement of the control frame 84 will cause activation of this contactor by the application cam 100 then by the washing cam 102, thereby supplying means for signaling the position of the control frame 84 relative to the chassis 80.

FIG. 14 is a top view, taken along the line 14-14 drawn in FIG. 13, which represents the control mechanism by which the frame 84 is moved up and down relative to the frame 80. A motor 126 for driving the frame 84 is fixed to the chassis 80 by means of a mounting screw 127. The motor 126 has on its output shaft a pinion 128 meshing with a first pinion 130 R mounted on the right end d a shaft 134 fitted on its left end with a second gear 130 L. The shaft 134 rotates in bearings mounted on supports 118 (the shaft 124 rotates in other bearings mounted on these same supports 118: cf. fig. II). The control frame 84 comprises racks 132 fixed on its rear face which pass through cutouts 136 made in the frames 80 and which mesh with FIGS. 130 R and 130
L. When the motor 126 rotates in one direction or the other, the frame 84 moves up or down relative to the frame 80. FIG. 13 shows the cutouts 136 made in the frames 80.

 FIG. 14 also represents the means by which the heads 193 of the pipette tubes 92 are removably fixed on the carrying beam 88. The beam of the tubes 88 comprises a receiving beam 138 provided with notches 140 formed in its front face. The heads of the tubes 193 are arranged in these notches and they are closed tightly by a fixing bar 139 and by screws 141. The beam 91 for holding the tubes 92 in vertical position is produced in the same way as the carrying beam 88. This beam 88 constitutes a removable fixing means by which the tubes 92 can be easily replaced when they are damaged.

 Figure 15 is a sectional view taken along line 15-15 of Figure 13, which shows the frame 80 in the down position. The control frame 84 has been lowered so that the beam of the pistons 90 is in contact with the beam of the tubes 88. FIG. 15 shows the racks 132 passing through cutouts made in the chassis 80 and their engagement with the teeth a pinion 130 driven by the motor 126. The tube 92 is, on this flower, lowered into the rinsing bowl 28, for example. The piston 94 was pushed down under the action of the control frame 84 moving the beam of the pistons 90 in its extreme low position. It goes without saying that, between FIGS. 12 and 15, the boss 22 of the plate 16 has been displaced longitudinally relative to the sub-assembly of the pipettes 70.

FIG. 16 schematically represents the means by which the movements of the carriage, the mounting frame and the control frame are controlled to carry out an automatic sampling operation. The dotted box 200 represents a nO microcircuit
HD 68 P01 V07 manufactured by the Hitachi Company. This circuit includes a central processing unit 201 A, a passive memory (ROM) 201 B, an active memory (RAM) 201 C, a time base 201 D, an output interface stage 201 E and an input interface stage 201 F. The passive memory 201 B contains software by means of which all of the automatic operations to be carried out are controlled, as will be explained below.

 FIG. 16 also represents the motor of the carriage 40, the motor of the chassis 116 and the motor of the frame 126, all these motors being placed under the commands of the central unit 201 A, through the control circuits of the motors 202, 203 and 204 which, for example, are circuits of the UDN - 2952 113 type manufactured by the Company Sprague. These motor control circuits are used to control their speed and their direction of rotation. In addition, circuits 205, 206 and 207 are provided for rapidly stopping the motors in response to particular signals produced by the processor 200. Such motor stop circuits will preferably be Triac circuits of the 2N6075 type.

 The position detection circuit 208 generally represents the displacement contactors 60 and 62 of FIG. 5 which indicate the positions of the carriage 46 and of the sample plate 16 relative to the subset 70 of the pipettes.

 The position detection circuit 209 generally represents the displacement contactors 105 and 106 which indicate the low and high limit positions of movement of the chassis 80 relative to the base 16.

 The position detection circuit 210 generally represents the displacement contactors 108 and 110 which indicate the relative positions of the control frame 84 and of the chassis 80. The signals associated with each of these position detection circuits are applied by a group of conductors 215, on the 201 F input interface stage of the electronic module 200.

 An alarm circuit 211 is provided for the device. This will be for example the EAF 14 R 06 C sound effect circuit manufactured by Panasonic. Such a circuit is activated and an audible signal is produced, whenever an implementation fault is committed or when the device is ready to operate.

 An indicator circuit 212 comprising a warning lamp is provided (cf. fig. 5) to signal to the user that the device is in the "On" position.

 A safety circuit 213 generally represents the contactor 65 (cf.

fig.5) which indicates the presence or absence of a tray 16 on the carriage 46. The control circuit 214 represents a push button used to start or stop the operating process of the device.

 In operation, the central processing unit 201 A receives a sequence of instructions from the software contained in the passive memory 201 B. The central processing unit 201 A also receives the position information relating to the mechanisms for moving the organs of the apparatus. This information is provided in the form of coded binary signals produced by the interface stage 201 F, which receives for this purpose the signals directly supplied by the position detection circuits 208, 209 and 210.

 The central unit 201 A of the microprocessor receives an input command to start or stop the process in the form of binary coded signals produced by the input interface stage 201 F, which receives for this purpose the signal directly supplied by the circuit. 214 shown in Figure 5.

 FIG. 17 represents the diagram of the functions governed by the central processing unit 201 A placed under the orders of the software contained in 201 113. The central processing unit 201 A determines the admissibility of a command to start the operating process of the the device, in response to coded binary signals supplied by the input interface stage 201 F which receives a signal from the safety circuit 213. This operation provides the assurance that the plate 16 has been completely inserted in the carriage 46.

 The central unit 201 A commands the motors 40, 116 and 126 to rotate in the required direction cn applying a specific coded binary signal to the output interface stage 201 E which is connected to the control circuits of the motors 202, 203 and 204 The central unit 201 A then orders the moving mechanisms to stop precisely when the required location has been reached. For this silence, new coded binary signals are applied to the output interface stage 201 E, which transmits appropriate orders to the control circuits 202, 203 and 204 of the motors and to their blocking circuits 205, 206 and 207.

 The microprocessor 201 A then signals that the fluid sampling device is ready to operate or that a tray has been inserted or that a fault has occurred, by sending an appropriate binary signal to the output interface stage 201 E, which in response will activate the alarm circuit 211.

 The time base 201 D of FIG. 16 is used by the central unit 201 A of the microprocessor to determine the electrical or mechanical failures of the movement mechanisms of the device. This operation is carried out by measuring the time that the control order of any motor lasts. If the commanded action is not performed within a predetermined time interval, the piloting command is stopped and the alarm is activated by the microprocessor 201 A which applies to the output interface stage appropriate binary signals and this stage activates in response the alarm circuit 211. The time base 201 D is also used to determine the rate of repetition of the alarms, thereby priming the microprocessor 201 A to record the nature of the failures and to communicate it to the operator.

 As shown in Figure 17, once the automatic pipette apparatus according to the invention is turned on, a wide variety of different applications can be obtained.

 The sequence of operations shown in Figure 17 is typical in that, first of all five microliters of a purifying agent such as distilled water, are drawn into the pipette tubes from the bowl of washing. Then, the water contained in the tubes is discharged into the discharge bowl and the necks of the tubes are dried by lowering them onto blotting paper (see fig. 5).

 Then the pipette tubes are moved to their high position, the pistons being in their low position, then the carriage is moved backwards and the tubes are lowered into their respective sample cells. The pistons are mounted, thereby sucking up a small amount of each liquid sample, from the blood of patients to be analyzed, for example. When no dilution of the blood samples is planned, the samples are then applied precisely to the strip of cellulose acetate or agarose placed on the tray. The tubes are raised again. Again the carriage is moved forward until the wash bowl is placed under the pipette tubes and the frame is lowered again so that distilled water is again drawn into the tubes and then discharged in the discharge bowl.

 When a dilution of the liquid samples is desired, the sample tray in Figure 2B will be substituted for that in Figure 2 and the processor program illustrated by the diagram in Figure 17 introduces the appropriate routine for this purpose. A preferred routine for diluting samples is to take an additional four microliters from the wash bowl. The effect of this is to introduce four microliters of a dilution liquid (water) in addition to the microliter of blood (or other organic liquid) into each pipette tube. Then all five microliters of liquid contained in each tube is applied to the respective dilution cells arranged on the sample tray of figure 2113. This process can be repeated several times to mix the initial sample and the dilution liquid (water).

Finally, a sample of a microliter of diluted blood is drawn into each tube, as explained above. The routine then proceeds as has already been described, whereby a volume of one microliter of diluted liquid sample is applied to the support medium.

 The above dilution routine is a preferred routine but others are possible to make a good mixture of a blood sample and a dilution liquid. For example, a first predetermined amount of the liquid sample contained in each tube can be applied to the dilution wells. A predetermined quantity of washing liquid is then applied to these same cells. After mixing the washing liquid and the sample present in a dilution well (for example by the technique described above), a small amount of diluted liquid is drawn from the dilution wells and applied to the support medium.

 Different modifications and variants can be made to the structures of the apparatus according to the invention described above. Those skilled in the art will find them while remaining within the scope of the present invention.

 Such modifications and variants are included in the claims expressed below from the embodiments of the invention described above by way of nonlimiting examples illustrated by the figures.

Claims (11)

 1. Applicator apparatus for pipettes of the type comprising a base (12), a removable plate (16) resting on a horizontal carriage (46) movable on said base, a vertical frame (80) movable on uprights (72) integral with said base, said frame carrying a row of pipettes (92), each pipette comprising a tube and a neck (93), and a frame (84) carrying a row of pistons (94) engaged in said tubes, means (40-38 -36) for longitudinally moving said carriage (46) and said plate (16) under the chassis (80), means (116-122) for vertically moving the chassis (80) relative to the carriage (46) and to the plate ( 16) and means (126-132) for vertically moving the frame (84) relative to said frame (80), said plate (16) being provided with a transverse row of cells (24) adapted to receive samples of fluids, characterized in that the plate (16) comprising a transverse application space (21) adapted to receive a support medium microporous (20), said means for moving the carriage (46), the chassis (80) and the frame (84) comprise motors (40-116-126) placed under the orders of control stages (205-206- 2u1) adapted to execute the instructions of a microprocessor (201 A) transmitted by an output interface stage (201 E), said microprocessor being placed under the dependence of an operational sequence generator (201-B) and of devices ( 208-209-210) indicators for the respective relative positions of the plate (16), of the chassis (80j and of the frame (84), said instructions having as their first object to have the row of pipettes (92) automatically withdraw the first predetermined volumes of samples of the fluids contained in the sample cells (24) and of applying them in a corresponding row of predetermined points (19) on said microporous support medium (20) by bringing the necks (93) of the pipettes (92) to touch said microporous support medium.  2. pipette applicator device according to claim 1, characterized in that the plate (16) including a transverse washing bowl (26) intended to receive a purification or dilution liquid and a transverse discharge bowl (28), said cuvettes being longitudinally spaced from each other and from the row of sample cells (24), the instructions of the microprocessor (201 A) have the second object of having the row of pipettes (92) take second volumes of predetermined purification liquid contained in the washing bowl (26) and then rejecting these second volumes in the discharge bowl (28).  3. pipette applicator device according to claim 2, characterized in that the tray (16) comprising between the discharge bowl (28) and the row of sample cells (24) a transverse drying space (32) adapted receiving a strip of blotting paper (30), the instructions of the microprocessor (201 A) have the third object of causing the necks (93) of the pipettes (92) to touch the blotting paper (30) so as to be dried after rejection of the second volumes of purification liquid in the discharge bowl (28).  4. pipette applicator device according to claim 2 characterized in that the tray (16) comprising a transverse row of dilution cells (25) disposed between the row (24) of fluid sample cells and the cuvette washing (26), the instructions of the microprocessor (201 A) have the fourth object of transferring said first predetermined volumes of liquid samples into said row of dilution cells (25), of having said row of pipettes (92 ), third predetermined volumes of purification liquid in said washing bowl (26), to transfer said third volumes of dilution liquid in said cells  dilution (25), mixing the fluids thus transferred into the dilution cells, having the row of pipettes (92) take a predetermined quantity of samples of diluted liquid contained in the dilution cells.  5. A pipette applicator device according to claim 1, characterized in that said tray (16) comprising a transverse bowl (26) intended to receive a dilution liquid and a transverse row of dilution cells (25) disposed between said bowl (20) and the row of sample cells (24), the instructions of the microprocessor (201 A) have the complementary object, after having the row of pipettes (92) take first predetermined volumes of fluid samples in said sample cells, having said row of pipettes take out second predetermined volumes of dilution liquid in said cuvette (26) in order to produce in the tubes of said pipettes a mixture of said first  and second volumes of fluids, discharging the mixtures thus obtained in the row of dilution cells (25) and then having the row of pipettes (92) take third predetermined volumes of samples of liquids  diluted.  6. Applicator apparatus for pipettes according to one of the preceding claims, characterized in that alarm devices (211) light and / or sound being provided and the microprocessor (201 A) being further placed under the dependence of a time base (201 D), said microprocessor is adapted to detect faults in the device and to produce instructions having the object of controlling the operation of said alarm devices (211) and the rapid stopping of the motors (40 -116-126) movement of the carriage (46), the chassis (80) and the frame (84) when the time intervals taken to execute  move instructions previously received by the respective floors  control (205-206-207) of said motors (40-116-126) do not comply  at predetermined time intervals allocated for this purpose.  7. Applicator apparatus for pipettes according to one of the preceding claims, characterized in that the displacement motors (40-116-126) of the mobile elements constituted by the carriage (40), the chassis (80) and the frame (84 ) are respectively associated with pairs of pinions (38, 120, 130) meshing with pairs of racks (36, 122, 132) respectively integral with said movable elements (40, 80, 84) and the devices indicating the respective relative positions of the carriage (40), the chassis (80) and the frame (84) are constituted by electrical contactor groups (60, 62) and (105, 106, 10X, 110) respectively integral with the base (12) and the chassis (80), said electrical contactors being equipped with pressure rollers adapted to cooperate with mechanical references constituted by the notches (50 to 59) formed on the longitudinal edges of the carriage (40), the stops (114, 115) mounted fixed on the upper and lower connection plates (82, 76) of the mounts vertical nts (72) of the chassis (80) and the cams (100, 102, 104) mounted fixed after adjustment on the frame (84).  8. Tray (16) 'for samples, suitable for use with a pipette applicator, characterized in that it comprises a transverse row of individual cells (24) intended to receive liquid samples and an application space transverse (21) intended to receive a microporous support medium (20).  9. A sample tray according to claim 8, characterized in that it comprises a washing bowl (26) and a discharge bowl (28), transversely disposed on the tray (16) and longitudinally spaced one of the other and from said row of sample cells (24).  10. A sample tray according to claim 9, characterized in that it comprises a drying space (32) transversely disposed on the tray (16) and longitudinally placed between said row of sample cells (24) and said bowl discharge (28), said drying space (32) being intended to receive a strip of blotting paper (30).  He. Sample tray according to claim 10, characterized in that it comprises between the row of individual sample cells (24) and said drying space (32) a transverse row of individual dilution cells (25) similar to the previous one.  12. Sample tray according to one of claims 8 to 11, characterized in that the upper edges of the washing and discharge cuvettes  (26-28) and individual sample and dilution cells (24-25) are arranged in the same plane, which is raised relative to the common plane  in which the drying space (32) and the application space are placed  (21).