JPH03186353A - Electromotive type pipette apparatus and titration method using the same - Google Patents

Abstract

PURPOSE:To suck and discharge a test solution in a predetermined set mode by a method wherein the home position of a piston converting the rotation of a stepping motor to linear reciprocating motion is set as a start position and the piston is allowed to advance and retract while controlled. CONSTITUTION:The rotary shaft 15a of a stepping motor 15 is rotated while controlled precisely and this rotary motion is made convertible to the linear reciprocating motion of a piston 24 through the conversion mechanisms 16, 21, 22, 23 connected to a linear shaft 25. When the piston 24 reaches the home position A0 of a cylinder chamber 28h, detection means 25, 27 detect this state to stop the driving of the stepping motor 15 and a test solution is brought to a state possible to suck. Thereafter, a tip leading end 30 is dipped in the test solution and the stepping motor 15 is reversed by a control means 20 and the piston 24 is drawn up to suck the test solution. Next, this apparatus is moved to a dripping place to drive the stepping motor 15 and the piston 24 is allowed to advance to the home position A0 and a two-stage discharge position A2 to discharge the sucked solution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric pipette device that sucks and discharges a test liquid or the like using a piston that reciprocates within a cylinder chamber, and a titration method using the same.

[Prior art] Conventionally, as this type of electric pipette device,
There is No.-193549.

This electric pipetting device consists of a pipette drive and a plurality of ejection assemblies. The pipette drive includes a digital linear actuator and a control circuit for controlling it, while the ejection assembly has a piston and a cylinder chamber each having a different ejection volume.

The digital linear actuator includes a linear shaft that is drivingly connected to the piston during assembly, and a step motor that linearly drives the linear shaft back and forth. This step motor is configured such that when the piston comes into contact with the bottom of the cylinder chamber, it slips and stops the downward movement of the piston.

The control circuit then reverses the stepper motor and raises the piston to a reference point called the home position. There is a sampling mode in which the test liquid is sucked in and the entire amount is discharged, an equal volume dispensing mode in which the test liquid is sucked in, distributed in equal amounts and then discharged, and a predetermined amount of the test liquid is sucked and then a predetermined amount of the diluted liquid is injected. The start of each inhalation in the dilution mode in which the test liquid is diluted by inhalation is controlled using this home position as the starting point.

[Problems to be Solved by the Invention] The conventional electric pipetting device described above slugs the piston when it comes into contact with the bottom of the cylinder chamber to stop the piston from descending, and then reverses the motor to bring the piston home. Since the piston is raised to the piston position, it has the disadvantage that it takes time to detect the home position of the piston. Furthermore, since it is necessary to cause the piston to slip when it comes into contact with the bottom of the cylinder chamber, the structure of the motor is complicated and expensive.

1. Means for Solving the Problems] An object of the present invention is to solve the problems of the prior art described above, and to provide an electric pipette device that can quickly and inexpensively detect the home position of a piston, and a titration using the same. The purpose is to provide a method.

A first aspect of the present invention is an electric pipette device that sucks and discharges a test liquid etc. using a piston that reciprocates in a cylinder chamber. A rotary motion/linear reciprocating motion converter tank that converts rotary motion into linear reciprocating motion, the rotary motion/linear reciprocating motion being drivingly connected to a linear shaft provided protruding from a piston reciprocating within a cylinder chamber. a conversion IIM; a home position detection means associated with the linear shaft for detecting the home position of the piston; and steps for moving the piston to various positions within the cylinder chamber starting from the home position of the piston. It is characterized by having a control means for driving the motor.

A second aspect of the present invention is a titration method for an electric pipette device in which a test liquid, etc. is drawn in and discharged by a piston reciprocating in a cylinder chamber, and the step motor is driven while precisely controlling the rotation angle. The home position of the piston is detected by converting the rotational motion of the rotary shaft into a linear reciprocating motion to cause the piston to reciprocate within the cylinder chamber, and the position of the linear shaft provided protruding from the piston. A step of stopping the rotation of the step motor, a step of driving the step motor in the direction of increasing the volume inside the cylinder chamber to suck in the test liquid, and a step of driving the step motor in the direction of decreasing the volume inside the cylinder chamber. and a step of discharging the test liquid or the like.

[Operation] The rotational motion of the 0-rotation axis, which is caused by driving the step motor by the control means and rotating the rotary shaft while precisely controlling it, is converted into a linear reciprocating motion by the rotational motion/linear reciprocating motion conversion RIII. This linear motion is transmitted to the piston within the cylinder chamber. When the piston reaches the home position within the cylinder chamber, the home position detection means detects this and stops driving the step motor. As a result, the electric pipette device becomes in a state in which it is possible to inhale the test liquid, etc. In the zeroth order, the tip of the electric pipette device is immersed in the test liquid, etc., and the control means is again energized. Thereby, the control means drives the step motor to increase the volume inside the cylinder chamber, and the zero-order system that sucks the test liquid, etc.
Depending on the setting mode of the electric pipetting device, the step motor is driven to increase or decrease the volume within the cylinder chamber. In other words, in the sampling mode, the inhaled test liquid is discharged in its entirety, in the equal volume dispensing mode, the inhaled test liquid is distributed in equal amounts and discharged, and in the dilution mode, the inhaled test liquid is discharged in equal amounts. Inject a predetermined amount of the diluent into the inhaled test solution, and then expel the entire amount.

[Actual example] Next, the electric pipette device of the present invention and the titration method using the same will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an example of an electric pipette device according to the present invention.

2 is a plan view of the electric pipetting device of FIG. 1; FIG.

The electric pipette device 10 according to the present invention is generally composed of an upper body 11 and a lower body 12 screwed to the upper body 11 with a fixing cap 13. Further, the lower body 12 includes an inner sleeve 14 and a cylinder member 28 that is snap-fitted to the lower side of the inner sleeve 14.

The upper body 11 can be divided into two parts, and is assembled and fixed using a required number of screws. A step motor 15 whose rotation angle can be precisely controlled is installed in a space lla formed inside the upper body 11. A gear 16 is fixed to the lower end of the rotating shaft 15a of the step motor 15. The space 11a of the upper body 11 also houses a battery 17 and a control panel 18.

Along the inner side surface of the upper body 11, the ejector shaft 19
is installed so that it can reciprocate in the vertical direction. An ejector button 19a is fixed to the upper end of the ejector shaft 19. On the back side of the control panel 18 is a control circuit 20 that can precisely control the rotation of the step motor 15.
is provided.

The control panel 18 includes, as shown in FIG.
Liquid crystal display 18a, on/off switch 18b, input switch 18 for displaying set capacity and execution operation
C. Button switches 18d and 18e for changing the set capacity, a switch 18f for mode switching, a switch 18g for answer back, a switch 18h for locking 'r-board operation, and a process switch 181 are provided. The functions of each switch will be described later along with the operation of the electric pipette device.

In the liquid crystal display 18a illustrated in FIG.
"D" represents sampling mode, rR-DJ represents equal volume dispensing mode, and rDL, J represents dilution mode.

Also, if the mode is sampling mode, “Vl
” is the inhalation amount of the test liquid. When the mode is equal volume dispensing mode, "Vl" and "V2" are the inhalation amount and equal volume dispensing amount of the test liquid, respectively. When the mode is the dilution mode, "Vl" and "V2" are the inhalation amount of the test liquid and the inhalation amount of the diluent, respectively. rLOcKJ is a struggle to display the lock status of keyboard operations.
MREAG, and DISPJ indicate that the device is in the suction operation state and that the device is in the ejection operation state. rULJ represents the unit of volume, i.e. microliter, and r) J is the answerback state. Each symbol indicates that it is in that state when the backlight illuminates the symbol.

In the space 14a formed inside the inner sleeve 14, there is provided a shaft 21 parallel to the rotating shaft 15a of the step motor 15.
is rotatably mounted. A male thread is cut on the outer periphery of the shaft 21. A gear 22 is also fixed to the upper part of the shaft 21, which meshes with the gear 16 of the rotating shaft 15a when the upper body 11 is combined with the lower body 12.

The block 23 is formed with a female thread 23a that threadably engages with the male thread of the shaft 21. The block 23 is also fixed to a linear shaft 25 that projects upwardly from the piston 24 and is fixed thereto. It engages with a protrusion 14b provided at the lower end of.

When the step motor 15 is rotated with the upper body 11 and the lower body 12 combined, the shaft 21 is rotated via the gears 16 and 22. The rotation of the shaft 21 is converted by the block 23 into linear reciprocating motion in the vertical direction.

A conductive plate 26 is attached to the inner wall of the inner sleeve 14 so as to be connected to a power supply circuit when the upper body 11 and the lower body 12 are combined. On the other hand, a conductive plate 27 connected to the power supply circuit is also attached to the block 23. As will be described later, the home position Ao of the piston 24 is detected by contact between the conductive plates 26 and 27. In the illustrated embodiment, a contact type electrical switch is used as the home position detection means. However, there are non-contact sensors,
For example, conventionally known sensors such as optical sensors and magnetic sensors can be selected and used.

The cylinder member 28 has four sleeve-like parts 28a, 28b, 28c and 28d having different diameters, and shoulders 28e, 28d.
f and 28g, respectively. A deflection insert 29 is inserted inside the sleeve-like portion 28d of the smallest diameter of the cylinder member 28. Further, a chip 30 having a chamber 30a for storing a test liquid or the like is attached around the sleeve-shaped portion 28d. The inside of the sleeve-shaped portion 28c of the second smallest diameter of the cylinder member 28 is
It is a cylinder chamber 28h that receives the piston 24, and is fluidly connected to the housing chamber 30a of the chip 30 through the sleeve-shaped portion 28d.

A retaining sleeve 31 is mounted inside the second largest diameter sleeve-shaped portion 28b of the cylinder member 28. An O-ring 32 is attached between the lower surface of the holding sleeve 31 and the inner wall surface of the shoulder portion 28f. A compression spring 33 is installed between the upper surface of the holding sleeve 31 and the lowermost surface of the inner sleeve 14. Therefore, when the inner sleeve 14 and the cylinder member 28 are snap-engaged, the holding sleeve 31 presses the O-ring 32 against the inner wall surface of the shoulder portion 28f, thereby sealing between the piston 24 and the cylinder chamber 28h. do.

The upper end of the cylinder member 28 extends outward in a brim shape to form a flange portion 28i. An ejector shaft 19 is attached to the inner sleeve 14 and the flange portion 28i of the cylinder member 28.
An opening is formed through which the lower part of the ejector shaft 19 passes, and the lower part of the ejector shaft 19 passes through this opening.

An ejector pipe 34 is attached to the outer periphery of the cylinder member 28 so as to be able to reciprocate in the axial direction with respect to the cylinder member 28 . The upper end of the ejector pipe 34 extends outward in a brim shape to form a flange portion 34a, and the lower end surface of the ejector shaft 19 is in contact with this flange portion 34a.

The fixed cap 13 is attached to the upper outer periphery of the cylinder member 28 and the ejector pipe 34.

Then, the lower body 12 is assembled and fixed to the upper body 11 by screwing the female screw portion formed on the upper inner wall surface of the fixing cap 13 to the male screw portion formed on the lower outer wall surface of the upper body 11. . Fixed cap 13
shoulder portion 13a and flange portion 34 of the ejector pipe 34
A compression spring 35 is installed between the

As a result, the ejector shaft 19 and the ejector pipe 3
4 is pushed upwards.

The stroke of the piston 24, that is, the home position Ao
It is preferable that the length from the position A1 to the maximum suction position A1 is about 20 mm, thereby improving the resolution of the electric pipette device.

In addition, in order to completely discharge the sucked test liquid, etc., the stroke required to move the piston 24 beyond the home position Ao to the predetermined second stage discharge position A2 is 21
It is preferably about 1I.

Next, the operation of the electric pipette device 10 according to the present invention will be explained.

The electric pipette device 10 has a cross-sectional area of the cylinder chamber 28h, for example, 0.01 to 10 (range of 7, 0.0
Range of 5-50Q, range of 0.2-200Q and 1.0
Titration specifications can range from 7 to 1000.

Furthermore, the operation mode of the electric pipette device 10 is as follows:
Sampling mode in which the test liquid is inhaled and all of it is discharged, equal volume dispensing mode in which the test liquid is inhaled, distributed in equal amounts and discharged, and test liquid is inhaled once and then a predetermined amount of diluted liquid is inhaled. There is a dilution mode that dilutes the test solution.

Therefore, an example will be described in which sampling of 29Q is performed using an electric pipette device 10 with a titration specification in the range of 1.0 to 100 (l).

In the electric pipetting device 10 according to the present invention, since the tip 30 is a disposable type, the tip 30 is not attached to the electric pipetting device 10 during use.
Therefore, first, attach the tip 3 to the lower end of the electric pipette device 10.
Attach 0. At this time, insert the chip 30 sufficiently until the upper end surface of the chip 30 comes into contact with the lower end surface of the ejector pipe 34 to prevent air leakage.

Press the on/off switch 18b on the control panel 18 to energize the electric pipetting device 10.

While looking at the liquid crystal display f8a of the control panel 18,
Press the mode changeover switch 18f and select the desired mode. For example, the sampling mode is when the backlight is at the rDJ position.

Next, press the input switch 18c and select the capacity to sample, in this case 29Q, using the button switch 18d.
and 18e. The sampling capacity is displayed in a number frame on the liquid crystal display 18a.

When the necessary input is completed, the lock switch 18h is pressed to lock the keyboard operation, and the electric pipette device 10 becomes operational in the sampling mode.

Next, when the process switch 18i is pressed, the control port F#1
20 drives the step motor 15 to move the piston 24 toward the home position Ao. Piston 2
4 reaches the home position Ao, the conductive route 26 and the conductive plate 27 come into contact. When the control circuit 20 senses this, it stops the rotation of the step motor 15, and at the same time indicates that the piston 24 has reached the home position Ao and the electric pipette device 10 is ready to aspirate the test liquid. Notify the operator with a buzzer.

The operator dips the tip of the tip 30 into the test liquid and presses the process switch 18i.The control circuit 20 then reverses the step motor 5 and moves it to a position corresponding to the sampling capacity (maximum stroke position A and home position Ao). 2) until the piston 24 is pulled up. When the suction of the test liquid is finished, the electric pipetting device 10 again notifies the operator with a buzzer sound.

The operator pulls up the tip of the tip 30 from the test liquid, moves it to the place where the test liquid is to be dropped, and presses the process switch 18i.The control circuit 20 reverses the step motor 5 and returns the piston 24 to the home position Ao. Stop driving the step motor 15. This results in
After a predetermined period of time has elapsed since the piston 24 returned to the home position Ao, the control circuit 20, which roughly discharges the test liquid, drives the step motor 15 again to move the piston beyond the home position Ao and perform a predetermined two-step discharge. (When the two-stage discharge of the test liquid remaining on the inner wall of the tip 30 is completely discharged by moving it to the device A2, the control circuit 20 returns the piston 24 to the home position Ao, and then , buzz the operator again and complete the sampling mode.

If you select the equal volume dispensing mode, enter the equal volume to be dispensed in addition to the inhalation volume of the test solution, and if you select the pain dispensing mode, enter the inhalation volume of the test solution as well as the volume of the diluent. Also enter the amount of inhalation.

It is preferable that the motor has two simultaneous rotational speeds so that when the equal volume dispensing mode is selected, dispensing can be performed at a slow speed.

[Effects of the Invention] As described above, the electric pipetting device of the present invention includes a step motor that can precisely control the rotation angle, and a rotary motion that converts the rotational motion of the rotating shaft of the step motor into linear reciprocating motion. A rotary motion/linear reciprocating motion converter RMA drivingly connected to a linear reciprocating motion converter (a linear jab protruding from a screw reciprocating in the cylinder chamber) and a home position of the piston. home position detection means provided in connection with the linear shaft to detect the piston, and control for driving a step motor to move the screw 1-n to various positions within the cylinder chamber, starting from the home position of the piston. Because it has the means to quickly and inexpensively
The home position of the engine can be detected.

Sampling mode in which the test liquid is inhaled and all of it is expelled; Equal volume dispensing mode in which the test liquid is inhaled, distributed in equal amounts and expelled; and the test liquid is inhaled in a predetermined amount and then a predetermined amount of pain solution is injected. In any dilution mode in which the test liquid is diluted by suction, the operation starts from the home position of the piston, so rapid detection of the home position of the piston greatly contributes to speeding up the titration work.

[Brief explanation of drawings]

Figure 5 is a longitudinal sectional view showing an embodiment of the electric pipette device according to the present invention. 2 is a plan view of the electric pipetting device of FIG. 1; FIG. FIG. 3 is a front view of the control panel illustrated in FIG. 1. 10...Electric pipette device 11...Jomon body lla...Space 12
...Shimonoseki body 13...Fixing cap 14...Inner sleeve 14a...Space 14b...Protrusion 15...
Step motor 15a...rotating shaft 16...gear
17... Battery 18... Control panel 18a... Liquid crystal display 18b... On/off switch 18c... Input switch 18d... Button switch 18e... Button switch 18f... Mode changeover switch 18g. ... Answer back switch 18h ... Lock switch 18i ... Process switch 19 ... Ejector shaft 19a ... Ejector button 20 ... Control circuit 21 ... Shaft 22 ... Gear 23 ... Block 23a... Female thread 24... Piston 2
5... Linear shaft 26.27... Conductive plate 28... Cylinder members 28a to 28d... Sleeve-shaped portions 28e to 28g... Shoulder part 28h... Cylinder chamber 28i... Flange part 29... Deflection insert 30... Chip 30a... Accommodation chamber 31... Holding sleeve 32... O-ring 34... Ejector pipe 33. 35... Compression spring

Claims (9)

[Claims] (1) An electric pipette device that sucks and discharges a test liquid, etc. using a piston that moves reciprocatingly within a cylinder chamber includes a step motor that can precisely control the rotation angle, and a linear reciprocating motion of the rotating shaft of the step motor. A rotary motion/linear reciprocating motion conversion mechanism that converts into motion,
a rotary motion/linear reciprocating motion converter tank drivingly connected to a linear shaft protruding from the piston that reciprocates within the cylinder chamber; and a control means for driving the step motor so as to move the piston to various positions within the cylinder chamber, starting from the home position of the piston. Electric pipetting device. (2) In the electric pipette device according to claim 1,
Furthermore, there is a sampling mode in which the test liquid is sucked in and the entire amount is discharged, an equal volume dispensing mode in which the test liquid is sucked in, distributed in equal amounts and then discharged, and a predetermined amount of the test liquid is sucked and then a predetermined amount of the diluted liquid is injected. An electric pipette device comprising an input means for selecting and setting a dilution mode for diluting a test liquid by inhalation. (3) In the electric pipette device according to claim 2, the control means is configured to move the piston beyond the home position to a predetermined two-stage discharge position in order to completely discharge the sucked test liquid, etc. drives the step motor. (4) In the electric pipette device according to claim 1,
Furthermore, an electric pipette device comprising a disposable tip fluidly connected to the cylinder chamber and having a storage chamber for storing an inhaled test liquid or the like. (5) In the electric pipette device according to claim 4,
Furthermore, an electric pipetting device characterized by comprising an ejector means for removing the tip from the electric pipetting device with one touch. (6) The electric pipetting device according to claim 1, wherein the home position detecting means comprises a contact switch. (7) The electric pipetting device according to claim 1, wherein the home position detection means is a non-contact sensor. (8) A titration method for an electric pipette device in which a test liquid, etc. is drawn in and discharged by a piston reciprocating in a cylinder chamber, the step motor being driven while precisely controlling the rotation angle;
The step of causing the piston to reciprocate within the cylinder chamber by converting the rotational motion of the rotary shaft into a linear reciprocating motion, and the position of the linear shaft provided protruding from the piston, directly determine the home position of the piston. detecting and thereby stopping the rotation of the step motor; driving the step motor in a direction to increase the volume within the cylinder chamber to suck in a test liquid, and the volume within the cylinder chamber; A titration method comprising the steps of: driving the step motor in a direction to decrease the amount of the test liquid, etc.; and discharging the test liquid or the like. (9) In the titration method according to claim 8, the step of discharging the test liquid, etc. includes a step of returning the piston to the home position and temporarily stopping the piston, and removing the residual test liquid, etc. held on the wall surface etc. A titration characterized by comprising the steps of: dropping a drop onto the tip of an electric pipette device; and moving the piston beyond the home position to a predetermined two-stage discharge position to push out the residual test liquid, etc. Method.