JP2020071191A - Dispenser - Google Patents

Abstract

Kind Code: A1 A dispensing device equipped with a small pressure sensor capable of measuring minute pressure changes in the vicinity of a nozzle is provided in order to detect dispensing errors and estimate a dispensing amount with high accuracy. A dispensing device according to the present invention has a pressure sensor arranged in the middle of a flow path of a liquid to be dispensed, the pressure sensor has a first flow path through which the liquid passes, and the first flow path The rigidity of the first surface in contact with is lower than the rigidity of the second surface. [Selection drawing] Fig. 3

Description

  The present invention relates to a dispensing device that sucks or discharges a liquid.

  The dispensing device is a device for performing dispensing in which a liquid such as a sample or a reagent is divided into a fixed amount, and is used in a blood analyzer and the like. The dispenser includes an elongated nozzle, a pipe connected to the nozzle, a syringe that allows liquid to be dispensed from the nozzle tip by supplying pressure, and a pressure sensor that measures the pressure in the pipe. The pressure sensor is used to detect a dispensing abnormality such as clogging in the pipe. In addition to this, it is desired that the pressure sensor estimate the dispensed amount from the pressure change between when the liquid is sucked and when the liquid is discharged.

  In estimating the dispensed amount, a small pressure sensor that can be installed in the arm portion near the nozzle is necessary to measure a minute pressure change near the nozzle. As such a small-sized pressure sensor, in Patent Document 1 below, a flexible silicone resin tube is connected between two pipes (stainless steel material) in a dispensing device, and the deformation of the resin tube is measured by a piezoelectric film. , A pressure sensor for measuring pressure from deformation of a resin tube is disclosed.

  The following Patent Document 2 discloses a pressure sensor structure having an upstream side connection port and a downstream side connection port connected to a pipe. Patent Document 2 has a structure in which the sensor main body is installed on the upper part of the pipe, and an opening is formed in the middle part of the pipe that continues from the upstream side connection port to the downstream side connection port, and the opening is formed in the sensor main body. It is sealed by the pressure receiving surface. Further, it has a projection for changing the direction of flow in the pipe to the direction of the opening so that air bubbles do not collect in the opening.

JP, 2005-114471, A JP, 2006-207946, A

  When the pressure is measured by using the deformation of the tube as in Patent Document 1, the deformation of the silicone resin tube is dispersed over the entire circumference of the tube, so that the amount of deformation of the portion to which the piezoelectric film is attached is small with respect to the change in pressure. .. This reduces the measurement sensitivity. Further, the flexibility of the tube easily causes external disturbance such as vibration, so that measurement noise occurs and the measurement accuracy decreases. Further, bubbles may be generated due to the step difference in the connection portion between the silicone resin tube and the stainless steel tube.

  Since the pressure loss and the turbulent flow are generated when the protrusion is formed in the middle portion of the pipe as in Patent Document 2, the pressure sensor structure of the document is not suitable for measuring a minute pressure. Further, the structure in which the projection is provided and the flow path is bent is not suitable for miniaturization of the sensor.

  The present invention has been made in view of the above problems, in order to accurately perform dispensing abnormality detection and dispensing amount estimation, it is possible to measure a minute pressure change in the vicinity of the nozzle of a small size. An object of the present invention is to provide a dispensing device equipped with a pressure sensor.

  In the dispensing device according to the present invention, a pressure sensor is arranged in the flow path of the liquid to be dispensed, the pressure sensor has a first flow path that allows the liquid to pass therethrough, and the first sensor is in contact with the first flow path. The rigidity of the surface is lower than the rigidity of the second surface.

  According to the dispensing device of the present invention, it is possible to provide a dispensing device that can measure a minute pressure change and that includes a small pressure sensor in which bubbles are less likely to accumulate. Since it is possible to measure a minute pressure change, it is possible to highly accurately detect the dispensing abnormality and estimate the dispensing amount.

It is a figure which shows the basic composition of the dispensing apparatus 1 which concerns on Embodiment 1. The state in the piping 8 immediately after sucking the liquid is shown. 6 is a diagram showing a structural example of a pressure sensor 15. FIG. It is the figure which expanded the area | region B of the lower stage of FIG. It is a figure explaining the 2nd method of measuring the dispensed amount of the liquid 22 using the measurement result by the pressure sensor 15. It is a figure which shows the constructional example of the pressure sensor 15 with which the dispensing apparatus 1 which concerns on Embodiment 2 is equipped. It is the figure which expanded the area | region D of the lower stage of FIG. It is a figure which shows the constructional example of the pressure sensor 15 with which the dispensing apparatus 1 which concerns on Embodiment 3 is equipped.

<Embodiment 1>
FIG. 1 is a diagram showing a basic configuration of a dispensing device 1 according to the first embodiment of the present invention. The flow path system of the dispensing device 1 has a nozzle 2, a syringe pump 4, a solenoid valve 5, a gear pump 6, and a system water tank 7, and each component is connected by a pipe 8. The syringe pump 4 includes a container 9, a plunger 10, a ball screw 11, and a drive motor 12. The drive motor 12 is controlled by the control unit 14 like the motor that drives the sample dispensing mechanism 13 and the like. A small pressure sensor 15 is arranged near the nozzle 2 in the arm 16. The sample dispensing mechanism 13 moves the nozzle 16 to a desired position by moving the arm 16 in the vertical direction or rotating it in a horizontal plane. The control unit 14 can be configured by using hardware such as a circuit device that implements the function, or can be configured by the arithmetic device performing software that implements the function.

  FIG. 2 shows a state in the pipe 8 immediately after sucking the liquid. The inside of the pipe 8 is filled with system water 21 for transmitting the syringe pressure, and the liquid 22 can be sucked and discharged from the nozzle 2 by the pressure change by the syringe pump 4. When sucking the liquid 22 from the nozzle 2, the plunger 10 in the syringe pump 4 is pulled with the electromagnetic valve 5 closed. When ejecting the liquid from the nozzle 2, the plunger 10 in the syringe pump 4 is pushed into the container 9 with the electromagnetic valve 5 closed.

  When sucking the liquid 22 such as a sample, the liquid 22 is sucked after the segment air 23 is sucked so that the liquid 22 does not mix with the system water 21 in the pipe 8. After ejecting the liquid 22, the nozzle 2 is washed. When cleaning the nozzle 2, the cleaning water is applied to the outer wall of the nozzle 2 and at the same time the system water 21 inside the flow path is pushed out. When the system water 21 in the nozzle 2 is pushed out in the cleaning process, the pressure of the gear pump 6 is used, so that the system water 21 is sent out at a higher pressure than when the syringe pump 4 pushes it out.

  As shown in FIG. 2, the pressure sensor 15 is preferably arranged as close to the nozzle 2 as possible within a range in which the liquid 22 or the segmented air 23 sucked at the time of dispensing does not touch the pressure sensor. This is because when the pressure sensor 15 is arranged at a position distant from the nozzle 2, the length of the pipe from the nozzle 2 to the pressure sensor 15 becomes long, and the thermal expansion of the pipe 8 is affected by the change in ambient temperature. Further, if the distance from the nozzle 2 to the pressure sensor 15 is increased, it is likely to be affected by disturbance such as vibration caused by driving the pump, so that it becomes difficult to measure a minute pressure change of the nozzle 2. Therefore, it is desirable that the pressure sensor 15 be as close to the nozzle 2 as possible.

  Specifically, the pressure sensor 15 is preferably arranged closer to the nozzle 2 than the contact point between the mechanism for moving the nozzle 2 up and down (the sample dispensing mechanism 13 in FIG. 1) and the arm 16. Even when the dispensing device 1 does not include the arm 16, it is desirable to dispose it on the side closer to the nozzle 2 than the movable part of the moving mechanism. This is because if the nozzle 2 is further separated, the influence of disturbance and thermal expansion will increase.

  FIG. 3 is a diagram showing a structural example of the pressure sensor 15. The upper part of FIG. 3 is a side sectional view parallel to the flow path. The lower part of FIG. 3 is a sectional view perpendicular to the flow path. The pressure sensor 15 includes a housing 32 and a strain measuring element 31. Although the cross-sectional shape of the housing 32 of this embodiment perpendicular to the flow path is circular, the shape is not limited and may be a quadrangle or the like. The housing 32 has a coaxial hole 33 and a screw hole 34. The coaxial hole 33 has the same diameter and center as the inner diameter of the pipe 8. The joint 37 also has a pipe 38 having the same diameter as the inner diameter of the pipe 8. The joint 37 can be fitted into the screw hole 34. The screw hole 34 is configured such that the pipe 38 and the coaxial hole 33 are connected on the straight line A when the joint 37 is fitted in the screw hole 34. As a result, the pipe 38 and the coaxial hole 33 are connected to the pipe 8 and a sample flow path can be formed.

  A recess 35 is provided on a surface 36 (first surface) on one side of the outer wall of the housing 32. In the housing 32, the portion having the recess 35 is thinner than the surface on the other side. Therefore, the surface on the concave portion 35 side has a lower rigidity than the surface on the other side. The strain measuring element 31 is arranged on the surface 36. When the system water 21 flows in the coaxial hole 33, the internal pressure is changed, and the surface 36 of the recess 35 is flexibly deformed. The strain measuring element 31 measures the strain to measure the pressure in the housing 32. The strain measuring element 31 can be configured by a strain gauge, a strain sensor chip, a piezoelectric element, or the like.

  FIG. 4 is an enlarged view of region B in the lower part of FIG. In FIG. 4, pressure (P in the figure) is applied to the inner surface of the coaxial hole 33. The displacement Δd of the surface 36 is concentrated on the thin wall portion and gradually decreases as the wall becomes thicker. Therefore, by disposing the strain measuring element 31 in the strained portion 41 or the strained portion 42 where the strain is more concentrated, the strain measurement accuracy is improved. Furthermore, since the pressure P can be calculated from the strain, the pressure measurement accuracy is also improved.

  In the strained portion 41, pressure is applied in the direction in which the strain measuring element 31 contracts, and in the strained portion 42, pressure is applied in the direction in which the strain measuring element 31 extends. By disposing the strain measuring element 31 at these two parts and using the two measurement results together, the measurement accuracy is improved. Only one of them can be used.

  The following methods are conceivable as a method of detecting the dispensing abnormality using the measurement result of the pressure sensor 15. Pressures in various dispensing states such as normal state and abnormal state are stored in the control unit 14 in advance as reference data. During the operation of the dispensing device 1, the control unit 14 determines the normal range and the abnormal range from the reference data, and determines that the dispensing is abnormal when the pressure waveform in the abnormal range is obtained. As shown in FIG. 2, by disposing the pressure sensor 15 near the nozzle 2, it is possible to accurately determine the pressure difference between the normal state and the abnormal state.

  The following two methods are conceivable as methods for the control unit 14 to measure the dispensed amount of the liquid 22 using the measurement result of the pressure sensor 15.

  In the first method, the relationship between the pressure measurement value and the flow rate of the system water 21 is obtained in advance, and the flow rate of the system water 21 obtained from the pressure is integrated over time to obtain the dispensed amount of the liquid 22. It is a thing.

  FIG. 5: is a figure explaining the 2nd method of measuring the dispensed amount of the liquid 22 using the measurement result by the pressure sensor 15. As shown in FIG. As shown in the upper part of FIG. 5, the two pressure sensors 15 and 15 ′ are arranged at an arbitrary interval L, or as shown in the lower part of FIG. 5, the two strain measuring elements 31 and 31 ′ are arranged at an arbitrary interval L ′. The two recesses 35 and 35 'arranged side by side are provided, and the flow rate of the system water 21 is obtained from the difference between the pressure measurement values of the two recesses. The subsequent procedure is the same as the first method.

In the second method, the relationship between the pressure measurement difference and the flow rate between the system water 21 is represented by the following equation 1. Q is the flow rate of the system water 21, Δp is the pressure difference between the pressure sensors 15 and 15 ′ or the strain measuring elements 31 and 31 ′, f is the dimensionless friction loss coefficient, and L is the pressure sensor 15. 15 'or the distance between the strain measuring elements 31 and 31', ρ is the density of the system water 21 and D is the inner diameter of the coaxial hole 33 (same as the inner diameter of the pipe 8):
Q = (32 · Δp) / (f · L · ρ · π 2 · D 4) ··· Formula 1

<Embodiment 1: Summary>
Since the dispensing device 1 according to the first embodiment measures the pressure by using the strain of the coaxial hole 33 that forms the flow path, the pressure sensor 15 can be integrally formed on the path of the flow path. As a result, the pressure sensor 15 can be downsized and can be arranged near the nozzle 2. Therefore, since a minute pressure change near the nozzle 2 can be measured, an abnormality such as nozzle clogging or empty suction can be accurately detected, and the dispensing amount can be accurately measured.

<Second Embodiment>
FIG. 6 is a diagram showing a structural example of the pressure sensor 15 included in the dispensing device 1 according to the second embodiment of the present invention. The upper part of FIG. 6 is a side sectional view parallel to the flow path. The lower part of FIG. 6 is a sectional view perpendicular to the flow path.

  In the second embodiment, the pressure sensor 15 includes the housing 32 and the strain measuring element 31 as in the first embodiment. The joint 37 is used to connect the pipe 38 on the straight line C. However, in the second embodiment, the coaxial hole 33 is offset by the distance S from the center of the housing 32 toward the outer surface of the housing 32. As a result, the surface on the side where the strain measuring element 31 is arranged becomes thin, so that it is not necessary to provide the recess 35.

  Since the coaxial hole 33 is offset, the joint 37 also has the hole 66 offset to a position communicating with the coaxial hole 33. By fitting the joint 37 in the hole 64, the hole 66 and the coaxial hole 33 communicate with each other. The holes 64 are preferably configured so that they can be connected by pushing in the joint 37, but the screw holes 34 of the first embodiment can also be used.

  FIG. 7 is an enlarged view of the area D in the lower part of FIG. In FIG. 7, pressure P is applied to the inner surface of the coaxial hole 33. The displacement Δd of the housing 32 is concentrated on the thin wall portion and gradually decreases as the wall becomes thicker. Therefore, by disposing the strain measuring element 31 in the strained portion 71 where the strain is more concentrated, the strain measuring efficiency is improved and the pressure can be measured with high sensitivity.

<Second Embodiment: Summary>
The dispensing device 1 according to the second embodiment can measure a minute pressure change near the nozzle 2 by disposing the small pressure sensor 15 near the nozzle 2 as in the first embodiment. Further, in the second embodiment, since the recess 35 is not necessary, there is an advantage that the process of processing the housing 32 is simplified. On the other hand, since processing precision is required when forming the coaxial hole 33, the first and second embodiments may be appropriately selected according to the required specifications.

<Third Embodiment>
FIG. 8: is a figure which shows the constructional example of the pressure sensor 15 with which the dispensing apparatus 1 which concerns on Embodiment 3 of this invention is equipped. The upper part of FIG. 8 is a side sectional view parallel to the flow path. The lower part of FIG. 8 is a cross-sectional view perpendicular to the flow path. The pressure sensor 15 according to the third embodiment includes a housing 32 and a strain measuring unit 803. The strain measurement unit 803 is a strain sensor chip and is used as a part of the outer wall of the flow path (direct contact with the system water 21).

  The housing 32 includes a recess 806 in which the strain measuring unit 803 (first member), the base 804 (second member), and the cap 805 are arranged. The recess 806 is formed by vertically cutting the flow path 814 of the housing 32 in the vertical direction of the paper surface. A unit including the strain measuring section 803, the base 804, and the cap 805 is called a sensor assembly 802. The housing 32 has a positioning hole 808 and a clamping screw hole 809 for clamping and sealing the sensor assembly 802 with a clamping joint 807.

  The housing 32 has a screw hole 812 for connecting the pipe connecting joint 811. The pipe connection joint 811 is a member for connecting the flow path 814 and the coaxial hole 33. The housing 32 further has a clamp joint screw hole 813 for connecting the pipe connecting joint 811 ′ via the clamp joint 807 in order to connect the pipe 8 from the clamp side.

  By using the sensor assembly 802, the clamp joint 807, and the pipe connection joint 811, the flow path 814 / the pipe 8 / the coaxial hole 33 can be formed coaxially without a step. In order to realize the sealing by clamping the sensor assembly 802, a sealing material such as rubber or gasket may be sandwiched.

  The strain measuring element 31 is incorporated in the thinnest surface of the strain measuring section 803 and measures the deformation of this surface. Since the resistance of the strain measuring element 31 changes due to strain, the pressure can be calculated from the resistance change of the strain measuring element 31.

  The signal pad 815 is arranged on the strain measuring section 803 and electrically connected to the strain measuring element 31. The terminals 817 on the substrate 818 and the signal pads 815 are connected via the wires 816. Through the terminal 817 and the signal pad 815, the measurement result by the strain measuring element 31 can be acquired.

  The strain measuring unit 803 bends in response to the pressure change of the system water 21 in the pipe, and the resistance of the strain measuring element 31 changes. The pressure can be measured by recording the correspondence between the resistance and the pressure as a data table in advance. For example, the relationship between pressure and resistance value may be formulated, and the measured resistance value may be converted into pressure. As a method of obtaining the resistance change of the strain measuring element 31, for example, one of the four resistances of the Wheatstone bridge may be replaced with the strain measuring element 31, and the resistance change may be obtained from the output of the Wheatstone bridge.

  The strain measuring unit 803 and the base 804 are formed in a shape that sandwiches the coaxial hole 33 from above and below, as shown in the lower part of FIG. 8, so that the coaxial hole 33 that is the same as the inner diameter of the pipe 8 is formed coaxially. As a result, no step is formed in the connection portion between the flow path 814 and the pipe 8, and thus it is possible to prevent pressure loss and inclusion of bubbles.

  The strain measuring section 803 can be made of a material having a high Young's modulus such as stainless steel, silicon, or glass. The base 804 and the cap 805 can be made of stainless steel, silicon, aluminum, Pyrex glass, or the like having higher rigidity. The strain measuring section 803 may be formed thinner than the base 804 in order to thin the portion where the strain measuring element 31 is arranged.

  As a method of joining the strain measuring section 803 and the base 804, a preferable method is selected depending on the material of the parts. Anodic bonding is preferred for silicon and Pyrex glass. When the metals are joined together or the metal and the silicon are joined together, metal joining or brazing such as soldering is preferable. In the case of soldering, it is necessary to form a thin film to improve the wettability of the solder. For example, when aluminum and silicon are used as the base materials, a thin film having a three-layer structure of titanium / platinum / gold can be bonded to the surfaces of aluminum and silicon by sputtering. The strain measuring section 803 and the base 804 may be joined with an adhesive.

  A gap is formed between the cap 805 and the strain measuring section 803. For example, even if a high pressure is applied to the flow path due to a pump failure or the like, the strain of the strain measuring unit 803 is suppressed with the void portion as the upper limit. This can prevent the strain measuring unit 803 from being destroyed.

1: Dispensing device 2: Nozzle 4: Syringe pump 5: Solenoid valve 6: Gear pump 7: System water tank 8: Piping 9: Container 10: Plunger 11: Ball screw 12: Drive motor 13: Sample dispensing mechanism 14: Control Part 15: Pressure sensor 16: Arm 21: System water 22: Liquid 23: Segmented air 31, 31 ': Strain measuring element 32: Housing 33: Coaxial hole 34: Screw holes 35, 35': Recesses 41, 42, 71 : Strained part 803: Strain measurement part 804: Base 805: Cap

Claims (12)

A dispensing device for dispensing a liquid,
A nozzle for sucking or discharging the liquid,
A pressure sensor for measuring the pressure of the liquid,
Equipped with
The pressure sensor has a first flow path through which the liquid passes,
The pressure sensor has first and second surfaces in contact with the first flow path,
The rigidity of the first surface is smaller than the rigidity of the second surface,
The pressure sensor has a first measuring element that measures the pressure based on the strain of the first surface,
The dispensing device further includes a sensor-nozzle flow passage, which connects the first flow passage and the nozzle to allow the liquid to pass from the first flow passage to the nozzle. apparatus. The dispensing device according to claim 1, wherein the first surface is configured to be thinner than the second surface, so that the rigidity of the first surface is smaller than the rigidity of the second surface. The first flow path is formed so as to penetrate the pressure sensor,
The first surface has a recess,
The dispensing device according to claim 2, wherein the thickness of the first surface of the recess is smaller than the thickness of the second surface. The dispensing device includes an arm that holds the nozzle, and a drive unit that moves the nozzle by moving the arm,
A second flow path is formed inside the arm for passing the liquid,
The said pressure sensor is arrange | positioned inside the said arm so that the said 1st flow path and the said 2nd flow path may connect. The dispensing apparatus of Claim 1 characterized by the above-mentioned. The dispensing device includes the nozzle,
The dispensing device according to claim 1, wherein the pressure sensor is formed as a part of the nozzle. The dispensing device includes a piping member having a third flow path through which the liquid passes,
The pressure sensor has a fitting hole for fitting the piping member,
The pipetting device is arranged so that the first flow path and the third flow path communicate with each other by fitting the piping member into the fitting hole. .. The pressure sensor further includes a second measuring element that measures the pressure based on the strain of the first surface,
The dispensing device further comprises a computing unit for determining the volume of the liquid,
The calculation unit obtains the flow rate of the liquid by the difference between the measurement results of the first and second measurement elements, and integrates the flow rate over time, so that the liquid sucked by the nozzle or discharged from the nozzle. The dispensing device according to claim 1, wherein the volume of The first flow path is arranged at a position offset from a central axis of the pressure sensor toward the first surface along a direction in which the first flow path extends. Dispenser. The pressure sensor has a first member and a second member that sandwich the first flow path,
The thickness of the first member is thinner than the thickness of the second member,
The dispensing device according to claim 1, wherein the first measuring element is embedded in the first member. The dispensing device according to claim 9, wherein the pressure sensor includes a cap that covers the surface of the first member to reinforce the rigidity of the first member. The dispensing device according to claim 10, wherein a gap portion is formed between the first member and a facing surface of the cap facing the first member. The dispensing device further includes a drive mechanism for moving the nozzle in the vertical direction,
The dispenser according to claim 1, wherein the pressure sensor is arranged on a path through which the liquid passes between the nozzle and the drive mechanism.

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