JPH10160738A - Pipet device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipet device capable of detecting the placement of a chip to a pipet main body, the contact of the chip with a liquid, and the attraction of the liquid into the chip by suction. SOLUTION: This pipet device is provided with a cylinder 3 which is provided for a pipet main body 2 and in which a piston 4 for attracting by suction and for discharging a liquid slides, the first and second conductive electrode members 5 and 6 provided in a nonconductive state with each other at predetermined locations in the periphery of the cylinder 3, a conductive chip 9 which is commonly fitted over the periphery of the first and second electrode members 5 and 6 and which attracts a liquid into the chip 9 by suction, and a control circuit 16 individually and electrically connected to the first and second electrode members 5 and 6. By forming a predetermined closed circuit through the conduction of the first and second electrode members 5 and 6 with each other via the chip 9 at the time of placing the conductive chip 9 to the first and second electrode members 5 and 6, the control circuit 16 detects the placement of the chip 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipette device capable of detecting that a tip has been attached to a pipette body, that the tip has touched a liquid, and that a liquid has been sucked into the tip.

[0002]

2. Description of the Related Art Generally, in the field of sampling,
A process of inhaling a predetermined amount of a sample with a pipette and dispensing it to other locations in smaller and smaller amounts at a time is performed. In recent years, a so-called automatic dispensing apparatus for automatically performing this process has appeared. In this case, in order to automate the step of aspirating a predetermined amount of the sample into the pipette, firstly, it is automatically and surely detected that the attachment of the tip to the pipette has been completed, and then the tip is moved down and the It is essential to accurately and automatically detect the time when the lower end contacts the liquid surface of the sample, and various attempts have been made for that.

[0003] First, as a conventional example (hereinafter referred to as a first conventional example) for detecting that the tip has been attached to the pipette, the pipette is moved down with respect to the tip rack to relatively move the tip. When the tip upper end is fitted to a predetermined position with respect to the lower end, the tip upper end pushes a mechanism interlocked with the microswitch on the pipette body side against the spring to switch the microswitch, and detects the completion of the tip mounting. there were.

Japanese Patent Application Laid-Open No. 63-1 (1988) discloses a conventional example for detecting the contact of a liquid surface of a chip (hereinafter referred to as a second conventional example).
No. 09330 “Liquid level detection method and device”
By moving the plunger (piston) 6, air is previously sent to the nozzle (tip) 2 via the pipe 9, and when the nozzle 2 comes into contact with the liquid level, the pressure in the pipe 9 increases. (2) Detecting contact with the liquid surface of No. 2 and then lifting nozzle 2 once to remove air bubbles at the tip of the nozzle, and then lowering nozzle 2 again to suck a predetermined amount of liquid into the nozzle was there.

Japanese Patent Laid-Open No. 2-19 describes a conventional example of detecting a liquid surface contact (hereinafter referred to as a third conventional example).
No. 6964, "Method for detecting liquid level of automatic dispensing device"
By calculating the pressure increase in the air hose 12 when the nozzle 14 comes into contact with the liquid surface, relative to the internal pressure reference value of the air hose 12 detected when the nozzle 14 is lowered,
In some cases, a predetermined amount of sample is sucked in spite of a change in the use conditions.

Further, a conventional example for detecting whether or not a sample is actually sucked into a chip (hereinafter, referred to as a fourth conventional example).
In this case, the operator had no choice but to visually recognize the image from outside.

[0007]

However, according to the first conventional example, the structure of the mechanical interlocking mechanism interlocking with the microswitch is complicated, and particularly in the case of a multi-pipette, the structure is complicated and cost is increased. There was a drawback that it became high.

Further, according to the second prior art, since the pressure of the air itself is apt to fluctuate due to the compressive fluid, the time point at which the liquid surface contact is detected is likely to be shifted, which may cause an error in the liquid suction amount. In addition, a change in the temperature, a change in the diameter of the suction port of the nozzle, or a change in the use conditions such as the suction performance specific to the apparatus easily causes a suction amount error, and the nozzle 2 is once moved up and down again. There was a drawback that the operation to perform was troublesome.

Further, according to the third conventional example, although the error of the suction amount due to the change of the use condition in the second conventional example can be eliminated, as described above, the deviation of the liquid surface contact detection time due to the pressure fluctuation of the air itself. There is a drawback that it is difficult to prevent an error in the amount of liquid suction due to the above.

Further, according to the fourth conventional example, it is difficult for an operator to visually check whether or not the sample has been sucked into the chip, and the operator is easily overlooked. In particular, when the chip is opaque, it is impossible to visually recognize the sample. there were. In addition, if these sample inhalations are overlooked or impossible to observe, especially when the sample is blood, the fibrin in the blood tends to clog the suction hole at the lower end of the chip in agar-like manner. However, even if the machine moves up and down to judge that the machine itself has inhaled the sample, the inhalation is not actually performed, and there is a disadvantage that serious malfunction of the machine occurs.

[0011]

A first example of a pipetting device according to the present invention is provided in a pipette body (2), and a piston (4) for sucking and discharging a liquid (11) slides inside the pipette body (2). The first and second conductive electrode members (5, 6) provided in a non-conductive state at predetermined positions on the outer periphery of the cylinder (3). A conductive tip (9) that is fitted and mounted in common on the outer peripheral portion of the second electrode member (5, 6) and sucks a liquid into the inside; and the first and second electrode members (5, 6). A control circuit (16) electrically connected to the first and second electrode members (5, 6) when the conductive chip (9) is mounted on the first and second electrode members (5, 6). And the second electrode members (5, 6) are electrically connected to each other via the chip (9) to form a predetermined closed circuit. Control circuit (16) and detects the mounting of the chip (9).

A second example of the pipette device according to the present invention is as follows.
A cylinder (3) provided in the pipette body (2), inside which a piston (4) for liquid suction and discharge slides;
A conductive electrode member (5) provided substantially at the tip of the cylinder (3); and a conductive tip (9) fitted and mounted on the outer peripheral portion of the electrode member (5) and sucking a liquid therein. , The electrode member (5) and the liquid (1) to be sucked into the pipette.
And 1) a control circuit (16) electrically connected individually to the electrode member when the conductive chip (9) comes into close contact with the liquid surface of the liquid. (5)
A predetermined closed circuit is formed between the liquid and the liquid via the chip (9), whereby the control circuit (16) detects the contact of the chip (9) with the liquid. .

A third example of the pipette device according to the present invention is as follows.
A cylinder (3) provided in the pipette body (2), a piston (4) sliding inside the cylinder (3) for liquid suction and discharge, and fitted and mounted on a predetermined portion of the pipette body. A chip (9) for sucking a liquid therein;
The piston (4) has a light emitting path (4a) for emitting light to the liquid sucked into the chip (9) and a light receiving path (4b) for receiving light reflected from the liquid surface of the liquid. It is characterized by having.

[0014]

According to the first embodiment of the present invention, when the tip is attached to the pipette using the conductive tip,
By electrically connecting the first and second electrode members of the pipette to each other, the attachment of the tip is reliably detected electrically,
Eliminate the complicated structure as in the case of mechanical mounting.

Next, by making the cylinder of the pipette conductive and electrically connecting the cylinder and the first electrode member to each other, the wiring from the control circuit is made to the cylinder and the second electrode member, thereby forming a wiring structure. To simplify.

Next, by interposing an insulating member between the second electrode member and the conductive cylinder, the two can be made coaxial, for example, to make the configuration compact.

According to the second embodiment of the present invention, the conductive member is used to contact the electrode member provided on the cylinder, and the electrode member and the liquid conduct when the chip comes into contact with the liquid surface. Thus, the point of contact of the liquid surface of the chip is detected, thereby eliminating the disadvantage of unstable liquid level detection using air pressure as in the conventional example.

According to the third embodiment of the present invention, the light emitting path and the light receiving path are provided in the piston itself sliding in the cylinder, and the reflected light on the liquid surface sucked into the chip is detected. Thus, whether or not the liquid has actually been sucked into the chip can be reliably detected electro-optically.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic sectional view of a pipette device according to the present invention.

In FIG. 1, reference numeral 1 denotes one of the multi-pipette devices (the other pipette devices have the same configuration and are not shown), and a conductive cylinder attached to the lower end of the pipette body 2 is shown. 3 This cylinder 3
Is made of, for example, stainless steel, and a seal 7 made of Teflon resin or the like is provided at an upper end thereof. As another cylinder material, a resin may be mixed with stainless steel powder to make it conductive.

Reference numeral 4 denotes a piston made of resin or stainless steel, which is vertically reciprocated by the operation of a push button on the upper part of the pipette device 1 and the action of a spring (both are not shown).
The piston 4 is further provided with an optical fiber having a light-emitting path 4a and a light-receiving path 4b for detecting the presence or absence of the liquid sucked into the chip in advance in the axial insertion hole.

Reference numeral 5 denotes a first relatively small-diameter conductive electrode member made of the same material as that of the cylinder 3 and having a substantially hollow truncated cone shape. Fixed. Alternatively, the first electrode member 5 may be formed from a conductive member integrated with the cylinder 3 from the beginning.

Reference numeral 6 denotes a second relatively large-diameter conductive electrode member made of the same material as that of the cylinder 3 and having a substantially truncated conical shape. And is fixedly fitted through. Therefore, the second electrode member 6 and the cylinder 3 are electrically non-conductive. As shown in FIG. 1, each outer periphery of the first and second electrode members 5 and 6 forms a cone-shaped outer diameter surface along an inner periphery of a chip 9 described later when viewed in the axial direction.

Reference numeral 9 denotes an opaque and conductive chip made by mixing carbon powder into a polypropylene resin or the like, which is previously held on a known chip rack (not shown).

Reference numeral 10 denotes a sample container, which is a sample 11 of an electrolyte liquid.
Is housed.

Reference numeral 16 denotes a control circuit, which is a total of 3 connected to the cylinder 3, the second electrode member 6, and the sample 11, respectively.
Book wiring 17, 18, 19, power supply 20, amplifier 21
A multiplexer 23 via a wiring 22a;
A / D converter 24 and central control unit (CPU) 25
And resistors R1 to R5 are appropriately arranged. In an initial state, a circuit between the wirings 17 and 18 (hereinafter, referred to as a first circuit) and a circuit between the wirings 17 and 19 (hereinafter, referred to as a second circuit) in the pipette device 1 are opened, respectively. It is assumed that voltages V1 and V2 are generated at resistors R1 and R2 between the ground and the ground, respectively. In this case, the wiring 17 is connected to the conductive cylinder 3,
The point is that the wiring 17 only needs to be connected and conductive to the first electrode member 5 via the cylinder 3. Therefore, the cylinder 3 itself is made of an insulating material, and the cylinder 3 is inserted in the axial direction so that the lower end of the cylinder 3 is in the first position. Another wiring connected to the electrode member 5 may be provided, and the wiring 17 may be connected to the upper end of the other wiring. Alternatively, if possible, wiring 1
7 may be directly connected to the first electrode member 5.

In the multi-pipette apparatus of the present embodiment, each pipette apparatus (not shown) other than the pipette apparatus 1 has the same configuration up to the amplifier 21 and the wiring 22b from each amplifier. .., 22n are all connected to the multiplexer 23.

FIG. 2 shows the output point P1 of the amplifier 21.
At the point P1 in the initial state, the voltage V3 at the point P1 is equal to the resistance R1.
V3 corresponding to R5.

Next, for the operation, only one pipette device 1 of the multi-pipette will be described for convenience, but the other pipette devices also operate synchronously.

First, when the pipette device 1 is automatically lowered with respect to a predetermined tip 9 among a plurality of tips held on a known tip rack (not shown), as shown in FIG. The chip 9 includes the first and second electrode members 5,
6 is fitted and mounted in common to the outer diameter portion. Accordingly, the first circuit (between the wirings 17 and 18) comprising the cylinder 3, the first electrode member 5, the chip 9 and the second electrode member 6 is closed, and is indicated by a two-dot chain line in FIG. Thus, the apparent resistance R'1, which is the sum of the resistance values inherent to the members 3, 5, 9 and 6, is generated in parallel with the resistance R1. Therefore, the voltage V1 becomes smaller than the initial value, so that the initial voltage V3 at the point P1 rises to V3a as shown in FIG. 2, and this is input from the multiplexer 23 and the A / D converter 24 to the CPU 25. Therefore, CP
U25 outputs a predetermined signal to stop the lowering operation of the pipette device 1, complete the mounting of the tip 9, and then raise it. According to this, since the attachment of the tip 9 to the pipette device 1 is electrically checked, the configuration does not become complicated as in the case of using a microswitch and a pressing spring.

Next, the pipette device 1 moves in the horizontal direction, starts to descend above the container 10 as shown in FIG. 1, and the lower end of the tip 9 contacts the liquid surface of the electrolyte sample 11. Thereby, a second circuit (wiring 1) including the cylinder 3, the first electrode member 5, the chip 9, and the path of the sample 11 is formed.
7 and 19) are closed, and as shown by the two-dot chain line in FIG. An apparent resistance R'2, which is the sum of the values, is generated in parallel with the resistance R2. Therefore, as shown in FIG.
Is smaller than the initial voltage V3, which is likewise
It is input to U25, which detects that the chip 9 has come into contact with the sample. Subsequently, the CPU 25 outputs a predetermined signal, and then the piston 4 is slid up from the lower limit position shown in FIG.
According to this, since the contact of the chip 9 with the sample liquid surface is directly and electrically detected, the detection accuracy is better and the contact with the sample liquid surface is better than when air pressure is used. Since the conductive tip 9 is used as it is as a member to be made, there is no need to provide a special liquid surface contact electrode member, and the configuration is simplified.

Subsequently, as shown in FIG. 3, the piston 4 moves up a little distance, and the sample 11 is sucked at the lower end of the chip 9. At this time, the light 26 from the light emission path 4a constantly receives the liquid surface of the sucked sample. It is emitted to 11 and reflected here, and some of it returns to the light receiving path 4b. Since the inside of the chip 9 has a conical shape, the area of the liquid surface of the sample 11 gradually increases with the inhalation of the sample 11, and the light reflected from the liquid surface also gradually increases. When the amount of the sucked sample 11 reaches a certain amount, the amount of light received by the light receiving path 4b reaches a certain value, which is converted into an electric signal by a predetermined optical-electrical signal conversion circuit (not shown). The suction of the sample 11 is detected.
In this case, it does not matter whether the chip 9 is conductive or not. Any material may be used, and the material of the chip 9 may be transparent or opaque. In the case of transparent, light from the outside of the chip enters the inside of the chip. It is preferable to be opaque because it may cause disturbance and cause erroneous detection.

According to this, since the fact that the sample is actually sucked into the chip 9 is detected electro-optically, there is no need for the worker to visually recognize the sample, the detection accuracy is improved, and the work can be performed. It will be easier. In particular, even if the sample is blood and fibrin is coagulated and the chip suction hole is closed, this can be detected immediately and malfunction can be prevented beforehand, so its utility is high. Conversely, the fact that the sample is actually discharged from the chip 9 can be similarly detected.

Next, FIG. 4 shows another example of the circuit of FIG.
In the figure, a pair of comparators 27a, 27 is provided for a multiplexer 23 instead of the A / D converter 24 of FIG.
b and one digital input / output circuit 28 are connected,
5A to 5C show voltage changes at points P1, P2, and P3 in FIG. 4, respectively.

According to this, one comparator 27a
5A compares the voltage V3a at the time of chip mounting with a predetermined reference voltage VA as shown in FIG. 5A, and digitally inputs a chip mounting detection signal V4a as shown in FIG. 5B when the voltage V3a is higher than the reference voltage VA. CPU via output circuit 28
25 to notify that the chip 9 is attached. The other comparator 27b compares the voltage V3b at the time of contact of the chip 9 with the liquid surface with a predetermined reference voltage VB to determine the voltage V3b.
Is smaller than the reference voltage VB, a liquid level contact detection signal V5a is output as shown in FIG. 5C to similarly notify the liquid level contact of the chip 9.

In the above embodiment, the pipette device 1 is described as a multi-pipette type. However, it is needless to say that only one pipette device 1 can be applied.

In the multi-pipette type, each mechanism for detecting the mounting of the chip 9 and for detecting the inhalation of the sample into the chip is preferably provided for each of the plurality of pipette devices 1. 1 in some cases
It may be provided only in one pipette device 1.

[0038]

As described above, the present invention has the following advantages.

When the tip is attached to the pipette using the conductive tip, the tip is electrically connected to the first and second electrode members of the pipette through the tip, thereby electrically connecting the tip. , Which eliminates the need for complicated configurations as in the case of using microswitches.
The configuration can be simplified and the detection accuracy can be improved.

By making the cylinder of the pipette conductive and electrically connecting the cylinder and the first electrode member to each other, wiring from the control circuit to the first electrode member is performed instead of wiring to the first electrode member. Then, by detecting the closing of conduction between the cylinder and the second electrode member, the wiring connection structure is simplified.

By interposing an insulating member between the second electrode member and the conductive cylinder, the two can be made to have a coaxial structure, for example, and the configuration can be made compact.

Using a conductive tip provided in the cylinder to contact the electrode member, when the tip comes into contact with the liquid surface, conduction between the electrode member and the liquid detects the time of the contact of the chip with the liquid surface. As a result, the instability of detection in liquid level detection using air pressure as in the conventional example can be eliminated, and the detection accuracy can be improved. In addition, since the chip comes into contact with the liquid level, the chip particularly comes into contact with the liquid level. There is no need to provide electrodes, and the configuration can be simplified.

A light-emitting path and a light-receiving path are provided on the piston itself that slides in the cylinder, and the reflected light on the liquid surface sucked into the chip is detected, thereby visually detecting whether or not liquid is sucked from the outside. Is unnecessary, and the suction or discharge of the liquid into the chip can be reliably detected electro-optically.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a partial cross-sectional configuration of a pipette device of the present invention.

FIG. 2 shows the voltage (V) at point P1 of the device of FIG.
FIG.

FIG. 3 is a sectional view of a part of the apparatus of FIG. 1;

FIG. 4 is a sectional view of another part of the apparatus of FIG. 1;

5A to 5C are diagrams showing voltage changes at points P1, P2, and P3 in FIG. 4, respectively.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pipette apparatus 2 Pipette main body 3 Cylinder 4 Piston 4a Light emission path 4b Light reception path 5 First electrode member 6 Second electrode member 8 Insulating member 9 Chip 11 Sample 16 Control circuit 17, 18, 19 Wiring 20 Power supply 23 Multiplexer 24 A / D
Converter 25 CPU 26 Light 27a, 27b Comparator 28 Digital input / output circuit

Claims (7)

[Claims] 1. A cylinder (3) provided on a pipette body (2), in which a piston (4) for sucking and discharging a liquid slides, and a cylinder (3) disposed at a predetermined position on the outer periphery of the cylinder (3). First and second conductive electrode members (5, 6) provided in a non-conductive state
A conductive tip (9) fitted and mounted in common on the outer periphery of the first and second electrode members (5, 6) and sucking a liquid therein; and the first and second electrodes A control circuit (16) electrically connected to each of the members (5, 6); and to the first and second electrode members (5, 6) of the conductive chip (9). When the control circuit (1) is mounted, the first and second electrode members (5, 6) are electrically connected to each other via the chip (9) to form a predetermined closed circuit.
6) detecting the mounting of the tip (9). 2. The device according to claim 1, wherein the cylinder (3) is made of a conductive material, and the cylinder (3) is electrically connected to the first electrode member (5). Non-conductive to the second electrode member (6);
The apparatus according to the preceding claim, wherein said control circuit (16) is electrically connected individually to said cylinder (3) and said second electrode member (6). 3. The device according to claim 2, wherein the second electrode member (6) and the cylinder (3) are electrically disconnected from each other by an insulating member (8) interposed therebetween. Said apparatus. 4. A cylinder (3) provided on a pipette body (2), in which a piston (4) for sucking and discharging a liquid slides, and a conductive member provided substantially at the tip of the cylinder (3). A conductive electrode member (5), a conductive tip (9) fitted and mounted on an outer peripheral portion of the electrode member (5) and sucking a liquid therein, the electrode member (5), and sucking into a pipette A control circuit (16) electrically connected to the liquid (11) to be processed, wherein the conductive chip (9) is close to the liquid level of the liquid (11). When a contact is made, a predetermined closed circuit is formed between the electrode member (5) and the liquid via the chip (9), so that the control circuit (16) is connected to the chip (9).
A pipette device for detecting contact of a liquid with a liquid. 5. The device according to claim 5, wherein the cylinder (3) is formed of a conductive material and is in electrical communication with the electrode member (5), and the control circuit (16) is connected to the electrode member. (5) The device as described above, which is individually and electrically connected to the cylinder (3). 6. The device according to claim 5, wherein the second electrode member (6) and the cylinder (3) are electrically disconnected from each other by an insulating member (8) interposed therebetween. Said apparatus. 7. A cylinder (3) provided in a pipette body (2), a piston (4) sliding inside the cylinder (3) for liquid suction and discharge, and a predetermined portion of the pipette body. A tip (9) fitted and fitted therein for sucking a liquid (11) therein, wherein the piston (4) emits light to the liquid sucked into the tip (9). A pipette device comprising: a path (4a); and a light receiving path (4b) for receiving light reflected from the liquid surface of the liquid.