JP4479654B2 - Method and apparatus for liquid dispensing - Google Patents

Description

  The present invention relates to a method and an apparatus for dispensing a sample or a reagent in an analyzer used in fields such as chemistry, industry, clinical practice, and biotechnology.

For the purpose of analyzing the mass of target molecules, a laser desorption ionization mass spectrometry method has been carried out in which a sample placed on a sample plate mounted on a mass spectrometer is ionized and analyzed by irradiating the sample with a laser beam. ing. When preparing a sample by placing it on a sample plate, there are a method using a matrix and a method not using it.
A method in which a method using a matrix is combined with a time-of-flight mass spectrometer is called a MALDI-TOF (matrix-assisted laser desorption ionization-time-of-flight) mass spectrometry method. In MALDI-TOF, a measurement sample is dropped on a sample plate together with a matrix solution, and measurement is performed after drying.
On the other hand, as a target sample, biomolecules are separated by electrophoresis, etc., transferred to a membrane and solidified, and the membrane is solidified on the membrane using a micro-dispensing technique using a piezo element. A method of performing mass spectrometry using reaction products produced by performing various reactions is proposed (see International Publication No. WO 98/47006 pamphlet).
There is an immunoblot method as a method for detecting a substance that is spread on a membrane and is immobilized. In general, immunoblotting is also called Western blotting, in which a protein sample is developed by electrophoresis, solidified on a membrane, and then reacted with a specific antibody against the target substance as a probe to detect its presence. is there.
After a reagent or sample is dispensed to a sample plate or an object with a membrane fixed on the sample plate by a dispensing mechanism such as a piezo element, the sample plate is separated from another device, such as a mass spectrometry system or other analytical device. Alternatively, transfer to a pre-processing device to perform analysis and next processing.
It is first necessary to accurately dispense reagents and samples only to the spots developed on the sample plate and membrane.
It is preferable that the dispensing element is clogged by the dispensing mechanism, or that the dispensing element (referred to as a dispensing element) can be replaced in order to dispense another reagent or sample. In that case, when a dispensing element is newly installed or replaced, it may shift from a predetermined position.
When the sample plate into which the reagent or sample has been dispensed is transferred to the next analyzer or processing apparatus, it is necessary to know the exact position where the reagent has been dispensed.
The request to know the position information when processing an object is not limited to the liquid dispensing device, but is common to various analysis devices and processing devices.
In the field of analyzers that often use a liquid phase regardless of sample or reagent, attempts have been made to reduce the amount of solution used for analysis. This not only saves valuable sample waste and reduces the amount of expensive reagents used, but in biochemical reactions between solutions, the smaller the amount of solution, the shorter the reaction time. Therefore, it is an effective method for increasing the processing efficiency of the experiment.
In order to carry out the reaction with a small amount of solution, a dispensing device for dispensing a sample or reagent in a minute amount is necessary. Various methods have been put to practical use, such as a method using a piezoelectric element such as a piezo element, a method by opening and closing a valve, and a method using bubbles generated by locally heating a solution as a method for dispensing a small amount of liquid. Has been.
When dispensing a small amount of liquid into a target container, delicate control of various parameters is required, such as how to apply a voltage to the element if a piezoelectric element, and opening and closing time if a valve is used. In order to optimize these parameters, and when dispensing into many positions, the dispensing time is long, so the shape of the droplet to be dispensed is monitored and the environment where the dispenser is located In order to cope with the change and the change with time of the piezoelectric element, an image of a droplet formed at the tip of the dispensing head is captured by an imaging device and monitored.
FIG. 16 shows a conventional dispensing device provided with an imaging device for monitoring the tip of the dispensing head.
Reference numeral 102 denotes a dispensing mechanism for dispensing a reagent, which has a nozzle at its lower end so that a small amount of reagent can be dropped. An XY table 104 is disposed below the dispensing mechanism 102, and an object to which a reagent is dispensed is placed on the XY table 104. The XY table 104 moves in the X direction and the Y direction within the horizontal plane, and positions the reagent dispensing position of the object below the nozzle of the dispensing mechanism 102.
Reference numeral 106 denotes an image pickup apparatus that monitors the state of droplets formed at the tip of the nozzle. A light source 108 is disposed on the opposite side of the image pickup apparatus 106 for monitoring with a transmission image.
In order to dispense accurately to the target dispensing position, it is preferable that the distance between the tip of the dispensing nozzle and the object is short. Therefore, the imaging device 106 that monitors the dispensing state is installed in a horizontal state, that is, at the same height as the nozzle tip.
Further, in order to perform stable dispensing at a large number of positions on the object, the object is placed on a movable table such as an XY table 104 as shown in FIG.
If the imaging device 106 is installed in the horizontal direction and interference between the XY table 104 and the imaging device 106 is to be avoided, the imaging device 106 must be attached outside the movement range of the XY table 104. Therefore, the device becomes larger.
As a dispensing device equipped with a piezo chip, the discharge part has a downward opening, and the liquid filled in the space connected to the discharge part is pressed by a drive part equipped with a piezo element, and the liquid is discharged from the discharge part. There is a dispensing unit with a piezo chip that ejects drops.
When dispensing a small amount of liquid from a piezo chip with such a dispensing device, there was no excess liquid at the tip of the piezo chip, and it was intended that the liquid was just filled to the tip. Liquid droplets cannot be ejected.
For this reason, until now, in the test dispensing before starting dispensing, the tip of the piezo chip is imaged with a CCD camera or the like, enlarged and displayed, and filled with manual operation while viewing the image, and excess liquid leaks from the tip. If so, it was wiped off.
However, with the conventional manual method, filling the piezo chip with liquid has been difficult without experience and it has been difficult to produce droplets of the intended size.
A small amount of pL to μL such as sample liquid and reagent liquid is dispensed by a piezo method or a syringe method.
As shown in FIG. 17, the piezo-type dispensing device includes a piezo chip 302 having a discharge portion at the tip. The piezo chip 2 ejects droplets 306 from the ejection unit by pressing a liquid reservoir connected to the ejection unit with a driving unit having a piezo element. A piezo dispensing control unit 304 is provided to control the driving unit to discharge a droplet having a certain size, and the piezo chip 302 is set according to the piezo element driving parameters set in the piezo dispensing control unit 304. A droplet 306 is discharged from the nozzle.
As shown in FIG. 18, the syringe-type dispensing apparatus discharges the droplet 6 from the probe 312 connected to the syringe pump 310 by driving a motor 314 that operates the syringe pump 310. A disposable (disposable) tip 316 may be provided at the tip of the probe 312. The chip 316 is replaced for each sample or reagent. By controlling the driving of the motor 314 by the syringe dispensing control unit 318 so that the operation parameters of the syringe pump 310 are set, a droplet 306 having a predetermined size is discharged.
Although the discharge conditions are set according to the liquid property such as the viscosity of the sample to be discharged and the reagent, the size of the discharged liquid droplets changes depending on the environmental conditions such as the temperature. Also, the smaller the amount of droplets, the more quantitative it becomes.
An object of the present invention is to enable accurate dispensing to a position to be dispensed.

The first aspect of the present invention achieves the above object by a dispensing device that can designate a position to be dispensed and automatically dispense the designated position.
The dispensing apparatus according to the first aspect includes a dispensing mechanism having a dispensing element for dropping a sample or a reagent, an image reading device for reading a lower image, and an object on which the sample or the reagent is to be dispensed. And a movable table that moves in a horizontal plane to position the object at least at a dispensing position below the dispensing element and an image reading position below the image reading device, and the image reading device reads the object. A monitor unit for displaying an image; a dispensing position designating unit for designating a dispensing position on an object based on an image of the object displayed on the monitor unit; and an object designated by the dispensing position designating unit A dispensing control unit that performs relative positioning of the object and the dispensing element so that the dispensing position on the object is below the dispensing element of the dispensing mechanism and controls the dispensing operation by the dispensing mechanism. And.
According to the dispensing device of the first aspect, the image read by the image reading device is displayed on the monitor unit, and the dispensing position on the object is designated based on the image of the object displayed on the monitor unit. As a result, the dispensing control unit performs relative positioning between the object and the dispensing element and controls the dispensing operation by the dispensing mechanism, so the dispensing position is specified on the image displayed on the monitor unit. By doing so, the reagent or sample is automatically dispensed to the designated position.
The dispensing mechanism may include a plurality of dispensing elements so that a plurality of types of reagents and samples can be injected into a common dispensing position or different dispensing positions.
A dispensing position information creation unit may be further provided, and dispensing position information related to the dispensing position on the object that has been designated and dispensed by the dispensing position designation unit may be created. Thereby, it can be left as information which position of the target object was dispensed.
Furthermore, the dispensing position information creation unit may output the created dispensing position information to the outside. The object into which the reagent or sample has been dispensed is transferred to an analyzer such as a mass spectrometer or transferred to a pretreatment device as necessary. At that time, the transfer destination analysis device or pre-processing device takes in the dispensing position information created and output by the dispensing position information creation unit, and analyzes the dispensing position by knowing the dispensed position of the object. It is possible to easily perform the operation of performing the pretreatment on the dispensing position.
The dispensing position designating unit may designate the dispensing position with a cursor, for example, on the object image displayed on the monitor unit.
In order to monitor the dispensing operation and adjust the discharge amount from the dispensing element, it is possible to further include an imaging device for imaging the tip of the dispensing element. In that case, when the dispensing mechanism includes a plurality of dispensing elements, the imaging apparatus performs a dispensing operation so as to image the tip of the dispensing element that performs the dispensing operation among the dispensing elements. It is supported by a moving mechanism so that it can move with the change of the dispensing element.
The second aspect of the present invention achieves the above object by enabling an accurate dispensing operation even when a dispensing element is newly attached or replaced.
The dispensing device of the second aspect is a dispensing mechanism in which a dispensing element for dropping a sample or a reagent is detachable, an image reading device for reading a lower image, and a sample or a reagent are dispensed. A movable table that supports an object on an upper surface and moves in a horizontal plane to position the object at least at a dispensing position below the dispensing element and an image reading position below the image reading device; and the dispensing. A dispensing position is detected on the basis of an image read by the image reading device when dispensing is performed at a predetermined position on the movable table by a mechanism, and a base point serving as a reference on the movable table is read simultaneously. And a calibration unit that calibrates the dispensing position.
The dispensing element of the dispensing mechanism is mounted at a predetermined position. To ensure that the dispensing position of the mounted dispensing element is always the same position, the dispensing element mounting part is advanced. High machining accuracy is required. In addition, there are machine differences in individual dispensing elements. For this reason, if an attempt is made to adjust the mounting of the dispensing element so that the dispensing position becomes a predetermined position, a high degree of machining accuracy and a skilled adjustment capability are required.
However, in the liquid dispensing device according to the second aspect, the dispensing element of the dispensing mechanism is detachable, and the image reading device is used when dispensing is performed at a predetermined position on the movable table by the dispensing element. The dispensing position is detected based on the image read by the camera, and the dispensing position is calibrated based on the reference base point on the movable table that is read at the same time. Adjustment work becomes simple.
The second aspect includes one provided with a plurality of dispensing elements. In that case, the calibration unit calibrates each dispensing element.
The third aspect of the present invention achieves the above object by a position information reading device that makes it possible to create accurate information on a position where liquid dispensing or other processing has been performed.
The position information reading device of the third aspect includes an image reading device that reads an image of an object on a table, and information on a position specified in the image based on the image read by the image reading device or A position information creating unit that creates information on the detected position based on a plurality of reference points serving as a reference on the object.
When obtaining information on the designated position on the object, the monitor unit that displays the image read by the image reading device, and the position on the object is designated based on the image of the object displayed on the monitor unit. The position information creating unit creates position information on the object designated by the position designating unit.
The position information reading device is based on a plurality of reference points serving as a reference on the object based on the information read by the image reading device or information on the position specified in the image. Thus, the position information in the object can be accurately determined based on the reference point.
Even when the object is moved to an analyzer or the like, it becomes possible to accurately position the object in the object from the position information based on the reference point.
The image reading device reads the image of the object as well as the image of the object, and the position information creation unit creates the position on the object based on a plurality of base points serving as a reference on the table. can do. Thereby, the information on the target position in the object can be accurately determined based on the base point. Even when the object is once removed from the table and attached to the table again, it becomes possible to accurately position the object in the object based on the position information based on the base point.
If the position information creation unit can output the created position information to the outside, even if the object is transferred to another device such as an analyzer, the position information can be accurately used for the target position. Can be positioned.
The fourth aspect of the present invention achieves the above object by using a sample plate that makes it possible to create accurate information regarding the position where liquid dispensing or other processing has been performed.
The sample plate of the fourth aspect is convenient for accurately obtaining position information, and is a plate-like body having a surface on which a sample or a reagent is to be dispensed, and a position reference within the surface. A plurality of marks are provided.
Since the sample plate is provided with a plurality of marks that serve as reference positions within the surface on which the sample or reagent is dispensed, it is convenient to create accurate positional information of the dispensing position within the sample plate.
The fifth aspect of the present invention achieves the above object by reducing the size of the dispensing device and providing a mechanism capable of monitoring the dispensing state.
The dispensing apparatus according to the fifth aspect includes a dispensing mechanism having a nozzle for dropping a sample or a reagent, an object to which the sample or the reagent is dispensed supported on an upper surface, and moves in a horizontal plane to move the object. A movable table that positions an object below the nozzle and a plane that is within the movable range of the movable table and is not in contact with the movable table, and images the tip of the nozzle from above obliquely. An imaging device.
By arranging the imaging device for monitoring the dispensing state obliquely upward with an angle from the horizontal direction, it can be installed within the movable range of the movable table without interfering with the movable table, The dispensing device becomes smaller.
A light source may be arranged on the opposite side of the imaging device across the nozzle tip, in which case the light emitted from the light source is reflected by the surface of the object and imaged via the nozzle tip. Directed to the direction of incidence on the device. By providing such a light source, when monitoring a sample or reagent droplet formed at the tip of the nozzle, it becomes possible to capture the image of the droplet with transmitted light, and a clearer image can be obtained. As a result, accurate monitoring can be performed.
The imaging device can also be set to capture an image of the surface of the object under the nozzle as well as an image of the tip of the nozzle. In that case, the state of the surface of the object can be monitored together with the monitoring of the nozzle tip, and more information can be obtained. For example, it is possible to check whether the sample or reagent has been accurately dispensed at the target position. For example, when the object to be sampled or dispensed is a membrane, the membrane before and after dispensing It is also possible to observe the state of the film and to observe the temporal change of the film state during the reaction.
The sixth aspect of the present invention is to achieve the above object by facilitating the adjustment of the amount of liquid at the tip of the piezo chip before the start of dispensing in the dispensing method and the dispensing apparatus using the piezo chip.
In the dispensing method of the sixth aspect, the discharge portion has a downward opening, and a liquid filled in a space connected to the discharge portion is pressed by a drive portion having a piezo element, whereby droplets are discharged from the discharge portion. In a dispensing method in a dispensing unit comprising a piezo chip that discharges a pressure, a pressure control mechanism that can adjust the pressure state of the liquid filled in the space, and an image pickup device that captures an image of the discharge unit, As a preparatory step before starting the dispensing operation from the piezo chip, after the liquid is filled in the space, the image is taken out by the image pickup device. A step of controlling the pressure control mechanism while obtaining a difference from the image before liquid filling and retreating the liquid until there is no difference from the image before liquid filling. Provide
The image of the tip of the piezo chip before filling the piezo chip with the liquid represents a state in which the liquid does not appear from the discharge unit, and is a state that becomes a reference when filling the piezo chip with the liquid. Thereafter, the liquid is poured into the piezo chip, the pressure is applied by the pressure control mechanism, and the liquid is supplied to the discharge portion of the piezo chip. This state is a state filled with liquid. An image of the ejection portion of the piezo chip is acquired from the start of liquid filling, and the difference from the image before filling is taken. When pressure is applied by the pressure control mechanism and it can be confirmed that an excess liquid amount appears from the discharge part as a difference between the images, feedback is applied to the pressure control so that the pressure control mechanism is set to negative pressure, Fix the pressure control where the liquid volume is not visible. This completes the preparation before the dispensing operation, and starts dispensing by discharging from that state.
If the process of this preparation stage is automated by the control device, pressure adjustment is automatically executed until dispensing with the piezo chip can be performed only by starting the filling of the liquid into the piezo chip.
The dispensing apparatus of the present invention in which the dispensing method according to the sixth aspect is executed includes a drive unit having a piezoelectric element, and a liquid filled in a space connected to the discharge unit, the discharge unit having a downward opening. A dispensing unit having a piezo chip that discharges droplets from the discharge unit when pressed by the pressure, a pressure control mechanism that can adjust the pressure state of the liquid filled in the space, and an image that captures an image of the discharge unit An apparatus, a storage device that stores an image captured by the imaging device, an image that is stored in the storage device with an image of a discharge unit before the space is filled with liquid, and an image that is after the space is filled with liquid In comparison, a control device is provided that controls the pressure control mechanism so that the liquid moves backward until there is no difference from the image before liquid filling after the liquid appears from the discharge section.
If the image pickup device is installed so as to pick up an image of the discharge section from the horizontal direction, the piezo chip can be more accurately filled with liquid.
Conventionally, it was necessary to perform delicate pressure control while viewing the image of the tip of the piezo chip with a manual, but in the present invention, the image of the ejection part before filling the piezo chip with the liquid is captured by the imaging device and stored. After the start of liquid filling, the pressure control mechanism is controlled while taking the image of the discharge part with the imaging device and obtaining the difference from the image before liquid filling, and after the liquid appears from the discharge part, before the liquid filling Since the liquid is retracted until there is no difference from the image, the liquid amount at the tip of the piezo chip can be easily adjusted.
Further, if this process is automated, pressure adjustment is automatically performed until dispensing with the piezo chip can be performed only by starting the filling of the liquid into the piezo chip. Furthermore, if the monitoring is continued even during standby, the state of the tip of the piezo chip can always be kept constant.
The seventh aspect of the present invention is to achieve the above object by enhancing the quantitativeness of dispensing of a small amount of sample liquid or reagent liquid.
In the quantitative dispensing method of the seventh aspect, an image of a droplet coming out from the discharge unit of the dispensing unit is acquired, the size of the droplet is obtained from the image, and the amount of dispensing of the droplet is controlled.
That is, the quantitative dispensing method includes the following steps (A) to (C).
(A) The step which acquires the image of the droplet discharged from the said discharge part.
(B) A step of obtaining the size of the droplet based on the captured image.
(C) A step of adjusting the parameter of the control signal to the discharge driving unit of the dispensing unit so that the dispensed amount of the droplet becomes a predetermined value based on the obtained droplet size.
As a result, the quantitativeness is improved in a small amount of pL to μL such as a sample solution or a reagent solution.
The size of the droplet obtained in step (B) is, for example, the diameter or radius of the droplet.
The step of obtaining the droplet size can be performed by automatic calculation using image processing. Such an image processing program can be easily obtained. If automatic calculation using image processing is used, the size of the droplet can be obtained quickly and accurately.
Also, the step of obtaining the droplet size can be performed manually on the image. According to the manual calculation, the cost required for the image processing program can be reduced.
The dispensing unit is a piezo dispensing method with a piezo head that ejects liquid droplets from the ejection unit by pressing the liquid filled in the space connected to the ejection unit at the tip with a drive unit equipped with a piezo element. Can be. In this case, the parameter of the control signal may include at least one of the magnitude of the applied voltage to the piezo element, the rising time of the applied voltage, the applying time, and the falling time of the applied voltage.
In addition, the dispensing unit can be of a dispensing system using a syringe pump. In that case, the parameter of the control signal may include at least one of the stroke, speed, and acceleration of the plunger of the syringe pump.
In the dispensing method using the syringe pump, the image for obtaining the size of the droplet can be an image of a droplet in a state of hanging in a ball shape at the tip of the discharge unit.
The step of adjusting the parameter of the control signal can be performed by automatic control by a control unit that controls the discharge driving unit. In that case, the number of man-hours for the operator can be reduced.
Further, the step of adjusting the parameter of the control signal can be performed by inputting to the control unit that controls the ejection driving unit. In that case, the system becomes simple.

FIG. 1 is a perspective view schematically showing an embodiment of a dispensing device.
FIG. 2 is a plan view showing the upper surface of the table on which sample plates and the like are arranged in the same embodiment.
FIG. 3 is a sectional view showing a dispensing mechanism in the same embodiment.
FIG. 4 is a block diagram showing the embodiment as a function.
FIG. 5 is a front view showing an embodiment of the dispensing device of the fifth aspect.
FIG. 6 is a schematic front view showing the vicinity of the nozzle tip in the same embodiment.
FIG. 7 is a block diagram schematically showing an embodiment of the sixth aspect.
FIG. 8 is a sectional view schematically showing an example of a piezo chip in the apparatus.
FIG. 9 is a flowchart showing the operation of the embodiment.
FIG. 10 is a block diagram schematically showing an apparatus to which the method of one embodiment of the seventh aspect is applied.
FIG. 11 is a sectional view schematically showing an example of a piezo chip in the apparatus.
FIG. 12 is a waveform diagram showing control parameters in the same embodiment.
FIG. 13 is a flowchart showing the operation of the embodiment.
FIG. 14 is a block diagram schematically showing an apparatus to which the method of another embodiment of the same aspect is applied.
FIG. 15 is a front view of the probe tip showing the dispensing mode in the same embodiment.
FIG. 16 is a front view showing a conventional dispensing apparatus corresponding to the dispensing apparatus of the fifth aspect.
FIG. 17 is a block diagram schematically showing a conventional piezo-type dispensing apparatus.
FIG. 18 is a block diagram schematically showing a conventional syringe-type dispensing device.

FIG. 1 schematically shows an embodiment of the liquid dispensing apparatus of the present invention.
Reference numeral 4 denotes a print head which is a dispensing mechanism, and four dispensing elements 10-1 to 10-4 each including a piezo element for dispensing a reagent and the like are mounted in a line. The positions of the dispensing elements 10-1 to 10-4 are fixed. In order to control the dispensing amount from the dispensing elements 10-1 to 10-4, a pressure control unit 7 for adjusting the pressure applied to the dispensing elements 10-1 to 10-4 is attached to the front surface of the apparatus main body. The four knobs 8 for adjusting the pressure in the dispensing elements 10-1 to 10-4 are arranged corresponding to the dispensing elements 10-1 to 10-4.
A scanner 6 is arranged as an image reading device for taking a sample plate to be dispensed as an image together with a table. The position of the scanner 6 is also fixed.
The table 2 is a movable table that can move in a horizontal plane. On the table 2, a sample plate 50 is placed at a predetermined position, as shown later with reference to FIG. The table 2 moves in a plane, the specified position of the sample plate 50 is positioned below the dispensing elements 10-1 to 10-4 at the time of dispensing, and the portion to be imaged on the table 2 is taken at the time of taking an image. Position below the scanner 6.
When dispensing from the dispensing elements 10-1 to 10-4, a CCD camera 5 is disposed as an imaging device to capture an image of the tip and monitor the state of dispensing. The CCD camera 5 is mounted so as to capture an image of the tip of the dispensing elements 10-1 to 10-4 from obliquely above in order to reduce the installation space. Dispensing elements 10-1 to 10-4 dispense different liquids. Dispensing elements 10-1 to 10-4 having predetermined dispensing positions such as sample plate 50 positioned downward are dispensed. Perform note operation. When the dispensing elements 10-1 to 10-4 performing the dispensing operation are changed, the camera 5 is arranged so as to capture images of the dispensing elements 10-1 to 10-4 performing the operation. It is attached so that it can move parallel to the array of 1-10-4.
The table 2, the print head 4, the camera 5 and the scanner 6 are housed in a case made up of a main body 9a and a lid 9b, and the case lid 9b can be opened at any time, for example, when the sample plate 50 is replaced. ing.
FIG. 2 shows a sample plate and the like arranged on the table 2.
Two sample plates 50 can be fixedly placed at predetermined positions. A membrane 52 is affixed on the sample plate 50, and a reagent and a sample are dispensed by this dispensing apparatus. Samples immobilized on the membrane 52 are, for example, proteins, peptides, sugars, lipids, nucleic acids, and the like separated and developed in a one-dimensional direction by SDS (sodium dodecyl sulfate) polyacrylamide gel electrophoresis or other chromatography. A molecule or a mixture thereof.
The sample can be immobilized on the membrane 52 by spreading the sample on a gel or other electrophoresis medium and then transferring it to the membrane 52.
Examples of the material of the membrane used for such solid phase include PVDF (polyvinylidene difluoride), nitrocellulose, nylon (registered trademark), and derivatives thereof.
In order to detect the substance in the spot which is developed on the membrane 52 and solidified, the digestive fluid and the extract from the dispensing elements 10-1 to 10-4 are applied to the sample components solidified on the membrane 52. Can be dispensed.
Moreover, the substance used as the probe couple | bonded with an object molecule | numerator can also be dispensed. As such a probe, an antibody is used when the target molecule is an antigen. In general, a biological substance that specifically reacts with a target molecule can be used. Also, several antibodies and biological materials can be used in combination.
It is preferable that the reagent is dispensed only in the area where the spot on the membrane 52 exists. Thereby, waste of reagents can be eliminated.
In order to enable optical detection of a target substance, a primary reagent including a probe that specifically reacts with the target substance as a reagent to be dispensed, and a secondary reagent that develops the target substance after reacting with the probe Can be used. In that case, the primary reagent is first dispensed from any of the dispensing elements 10-1 to 10-4, and then from the other of the dispensing elements 10-1 to 10-4 on the area where the primary reagent has been dispensed. Dispense secondary reagent. As such a secondary reagent, a coloring reagent or a fluorescent reagent can be used.
In addition, after reacting the probe with the target molecule and detecting it by an appropriate means, in addition to dispensing a coloring reagent or fluorescent reagent, reacting metal ions or combining these methods be able to. As such a method, there are a method using a colloidal gold labeled antibody and a method of introducing a protein having affinity for metal ions into a fluorescent reaction using Ni ²⁺ chelate enzyme or the like.
Since a plurality of dispensing elements 10-1 to 10-4 are provided, by moving the dispensing position on the sample plate 50 by the table 2, the dispensing elements 10-1 to 10-4 are changed to a plurality. Can be dispensed.
Each sample plate 50 is provided with a plurality of marks b. These marks b are reference points that serve as a reference when creating the dispensing position on the membrane 52 affixed on the sample plate 50 as information. In this example, reference points b are provided at four corners of a substantially rectangular shape, and these reference points b are captured by the scanner 6 together with the image of the membrane 52. One corner of the sample plate 50 is cut off to indicate the orientation of the sample plate 50.
An area 54 provided on the table 2 is an area provided as a test print unit for performing a dispensing test using the dispensing elements 10-1 to 10-4. A filter paper is also attached there, and the dispensing state at the time of test printing can be confirmed by the CCD camera 5.
A region 56 provided on the table 2 is a maintenance unit for the dispensing elements 10-1 to 10-4, and a sponge 57 is provided. When liquid or dirt adheres to the tip of the dispensing elements 10-1 to 10-4, the maintenance unit is moved under the dispensing elements 10-1 to 10-4, and the dispensing element is moved by the sponge 57. The liquid and dirt attached to the tips of 10-1 to 10-4 are wiped off.
Further, a mark a is provided on the surface of the table 2 as a base point serving as a reference for the position of the sample plate 50 disposed on the table 2. The mark a serves as a reference when the dispensing position is taken out as information, and serves as a reference for matching the position on the image acquired by the scanner 6 with the movement of the table 2. Each dispensing element 10-1 to 10-4 in the head 4 has the same structure.
An example of the liquid dispensing apparatus used for the micro-dispensing method is the one using the piezo element described above. In such a liquid dispensing apparatus, a reagent filled in a space connected to the discharge unit at the tip is pressed by a drive unit including a piezo element, thereby discharging a droplet from the discharge unit. In this case, the parameter of the control signal may include at least one of the magnitude of the applied voltage to the piezo element, the rising time of the applied voltage, the applying time, and the falling time of the applied voltage.
As a liquid dispensing apparatus similar to this, an apparatus provided with a liquid ejection element used in an ink jet type liquid ejection apparatus can be used.
As another example of the liquid dispensing apparatus used in the microdispensing system, a dispensing system apparatus using a syringe pump can also be used. In that case, the parameter of the control signal may include at least one of the stroke, speed, and acceleration of the plunger of the syringe pump.
An example of a dispensing mechanism provided with a piezo chip 10 incorporating a piezo element as a dispensing element will be described in detail with reference to FIG.
A piezo chip 10 as a liquid discharge unit having a discharge port at the lower end and a hollow needle 16 at the upper end is detachably attached to a chip holding unit 31 of the liquid dispensing device by a screw 29. The piezo chip 10 can be removed by loosening the screw 29 and can be fixed by tightening the screw 29. When the piezo chip 10 is attached or detached, the dispensing position shifts. Therefore, as described later, in this embodiment, the dispensing position is calibrated with reference to the base point a on the table 2.
Dispensing liquid container 20 is disposable, and has an opening at the lower end and the upper end, and the lower end opening is closed by lid 15 to store the dispensing liquid therein. The lid 15 at the lower end opening is an elastic septum, and is constituted by an elastic member that can be penetrated by the hollow needle 16 of the piezo chip 10 and that the through hole can be closed by elasticity when the penetrated hollow needle 16 is pulled out. . The elastic member constituting the lid 15 is, for example, rubber.
The air introduction head 30 can be attached from the upper part of the container 20 in a state in which the container 20 is mounted on the chip 10 and mounted through the hollow needle 16 through the lid 15 at the lower end opening. The air introduction head 30 adjusts the pressure in the container 20 and adjusts the amount of liquid discharged from the chip 10.
A seal member 32 is provided at the tip of the air introduction head 30. The seal member 32 is an O-ring, for example. By pressing the air introduction head 30 against the container 20, the sealing member 32 comes into contact with the inner surface of the opening of the container 20 to seal the opening of the container 20 while keeping the air tight, and pressure is applied to the air introduction head 30. The pressure in the container 20 can be controlled by the air sent from the control mechanism.
An arm mechanism is provided for detachably mounting the air introduction head 30. The arm mechanism includes an arm 33 and a lock 36, and the air introduction head 30 is held at one end of the arm 33. The base end portion of the arm 33 is rotatably supported by the liquid dispensing apparatus main body by a pin 34. The lock 36 is rotatably supported by the arm 33 by a pin 38, and a flange 40 is provided at the base end portion. The ridge 40 engages with a convex portion 35 fixed to the liquid dispensing apparatus main body, and can be locked in a state where the container 20 is mounted on the chip 10.
The air introduction head 30 is slidably inserted into a hole formed in the arm 33 and is urged by the spring 41 so as to push the air introduction head 30 toward the container 20. The base end portion of the air introduction head 30 protrudes from the arm 33, and the flange 45 is provided at that portion, so that the air introduction head 30 is prevented from coming out of the arm 33. A base end portion of the air introduction head 30 is connected to a pressure control mechanism via a pipe 44.
A coil spring 42 in a compressed state is inserted between the arm 33 and the lock 36 in order to urge the lock 36 in the direction in which the flange 40 engages with the projection 35 around the pin 38.
A spring 43 is placed between the arm 33 and the liquid dispensing apparatus main body, and the spring 43 biases the arm 33 to be pulled in the opening direction (clockwise direction in the figure).
In the mechanism of FIG. 3, when the container 20 is mounted, the container 20 is placed on the chip 10, pushed downward, penetrates the septum 15 with the hollow needle 16, and the hollow needle 16 is immersed in the solution in the container 20. Since the air introduction head 30 is held by the arm 33, the air introduction head 30 is attached to the opening of the container 20 by rotating the arm 33 counterclockwise in the figure, and the container 20 and the air introduction head 30 are thus mounted. Are connected to each other by the seal member 32 in an airtight manner. At this time, the collar 40 is engaged with the convex portion 35 to lock the arm 33 and prevent the arm 33 from rotating clockwise so as to open. Since the air introduction head 30 is biased so as to be pressed in the direction of the container 20 by the spring 41, the airtight connection between the container 20 and the head 30 is maintained with the arm 33 locked.
In this state, the liquid can be discharged from the chip 10.
When removing the container 20, the lock 36 is pushed in the direction of the arm 33. The lock 36 pivots clockwise around the pin 38 in the figure, the engagement between the collar 40 and the projection 35 is released, and the arm 33 pivots clockwise in the figure due to the force of the spring 43, and the air introduction head 30 leaves the container 20.
In this state, the air introduction head 30 rotates around the pin 34 together with the arm mechanism, so that the space between the air introduction head 30 and the container 20 opens widely, and the sealing material 32 of the air introduction head 30 and the cleaning around the container 20 are cleaned. This makes it easier to maintain.
Further, if the air introduction head 30 can be attached to and detached from the container 20 using the arm mechanism in this way, the attachment and detachment of the container 20 and the attachment and detachment of the air introduction head 30 to the container 20 can be easily performed. It becomes like this.
Returning to FIG. 1, the CCD camera 5 will be described.
In the field of analyzers that often use a liquid phase regardless of samples and reagents, attempts have been made to reduce the amount of solution used for analysis. This not only saves valuable sample waste and reduces the amount of expensive reagents used, but in biochemical reactions between solutions, the smaller the amount of solution, the shorter the reaction time. Therefore, it is an effective method for increasing the processing efficiency of the experiment.
In order to carry out the reaction with a small amount of solution, a dispensing device for dispensing a sample or reagent in a minute amount is necessary. As a method for dispensing a small amount of liquid, there are various methods such as a method using a piezoelectric element such as the piezo element of the embodiment, a method by opening and closing a valve, a method using bubbles generated by locally heating a solution, etc. Has been put to practical use.
When dispensing a small amount of liquid to a target position, delicate control of various parameters is required, such as how to apply a voltage to the element if it is a piezoelectric element, and opening and closing time if a valve is used. In order to optimize these parameters, and when dispensing to many locations, the dispensing time also becomes long, so the shape of the droplet to be dispensed is monitored and the environment where the dispenser is located In order to cope with the change and the change over time of the piezoelectric element, it is preferable to capture and monitor the image of the droplet formed on the tip of the dispensing element with an imaging device. The CCD camera 5 is an example of such an imaging device.
By disposing the CCD camera 5 for monitoring the dispensing state at an angle with respect to the horizontal direction, the CCD camera 5 can be installed within the moving range of the movable table 2 without interfering with the movable table 2. And the dispenser becomes smaller.
A light source may be arranged at a position opposite to the CCD camera 5 across the tip of the dispensing element. In this case, the light source reflects the light emitted from the surface of the sample plate 50 as a target and dispenses. It is directed in the direction of incidence on the CCD camera 5 via the element tip. By providing such a light source, when monitoring a sample or reagent droplet formed at the tip of the dispensing element, it becomes possible to capture the image of the droplet with transmitted light, resulting in a clearer image. An image can be obtained and an accurate monitor can be performed. Further, by turning on the light source in synchronization with the dispensing timing, it is possible to capture the droplet as a still image.
The CCD camera 5 can also be set so as to capture an image of the surface of the sample plate below the dispensing element as well as an image of the tip of the dispensing element. In that case, the state of the surface of the sample plate can be monitored together with the monitoring of the tip of the dispensing element, and more information can be obtained. For example, it becomes possible to confirm whether or not the sample or reagent is accurately dispensed at the target position. For example, when the object to which the sample or reagent is dispensed is a membrane, the membrane before and after dispensing It is also possible to observe the state of the film and to observe the temporal change of the film state during the reaction.
As an application of this dispensing apparatus, for example, an apparatus that dispenses a reagent to a solid phase such as a PVDF (polyvinylidene difluoride) membrane can be cited. A spot developed by chromatography is transferred to the PVDF membrane, and a reagent is dispensed to develop the color of the spot. As such a solid phase, nitrocellulose, nylon (registered trademark), or the like can be used in addition to the PVDF membrane.
FIG. 4 shows the function of the apparatus of FIG. 1 as a block diagram.
Reference numeral 60 denotes a monitor unit that displays an image read by the image reading device 6 such as a scanner. The dispensing position designating unit 62 is for designating the dispensing position on the object 50 based on the image of the object 50 such as a membrane displayed on the monitor unit 60. The dispensing control unit 64 performs relative positioning of the object and the dispensing element so that the dispensing position on the object designated by the dispensing position designating unit 62 is below the dispensing element of the dispensing element 10. The dispensing operation by the dispensing element 10 is controlled. When the dispensing element 10 has a piezo element, the dispensing control unit 64 adjusts the pressure in the dispensing element 10 by the pressure control unit 7, and the voltage to the piezo element by the dispensing control unit 66. The liquid is discharged from the piezoelectric element by controlling the application.
The dispensing position information creation unit 68 creates dispensing position information related to the dispensing position on the object 50 that has been designated and dispensed by the dispensing position designation unit 62. The dispensing position information creation unit 68 can output the created dispensing position information to the outside.
As shown in FIG. 2, the object 50 is provided with a plurality of reference points b that serve as a reference for the position in the object, and the image reading device 6 reads the image of the object 50 together with the image of the object 50. Like that. As a result, the analysis position information creation unit 68 can create the position on the object 50 designated by the analysis position designation unit 62 based on the plurality of reference points b. Even when mounted on the table 2, if an image is acquired by the scanner 6, the positioning can be performed accurately based on the reference point b. Further, even when the object 50 is moved to an analyzer or the like, it is possible to accurately position the dispensing position in the object 50 from the dispensing position information based on the reference point b. Become.
The table 2 that supports the object is driven by the table driving mechanism 65 and moves in a plane, and is positioned at a predetermined position designated by the dispensing control unit 64. A plurality of base points a serving as a reference are provided on the table 2 so that the image reading device 6 reads the image of the base point a together with the image of the object 50, and the analysis position information creation unit 68 includes the object 50. The upper position can be created based on a plurality of base points a. Thereby, the dispensing position information in the object 50 can be accurately determined based on the base point a.
The dispensing element 10 for dropping the sample or reagent is detachable and includes a calibration unit 72 for calibrating the dispensing position of the dispensing element 10. The calibration unit 72 detects the dispensing position based on the image read by the image reading device 6 when the dispensing element 10 dispenses a predetermined position on the table 2, and simultaneously reads the reference on the table. The dispensing position is calibrated based on the base point. Dispensing for calibration is performed at a plurality of predetermined positions as indicated by three points by the membrane 53 that develops color when, for example, the reagent on the table 2 shown in FIG. 2 is dispensed. This calibration is performed each time the dispensing element is mounted.
In the above embodiment, the case where the present invention is applied to a dispensing apparatus has been described as an example. However, position information to be obtained is not limited to dispensing position information, and images of membranes, electrophoresis media, and the like are displayed as images. The present invention can be similarly applied to the case where information of a detected position such as a spot in an image is read by a reading device.
An example of the dispensing device according to the fifth aspect will be described.
FIG. 5 shows one embodiment of the dispensing apparatus of the same aspect. The dispensing mechanism 102 for dispensing the reagent (or sample) has a nozzle at its lower end so that a minute amount of liquid can be dropped. An XY table 104 as a movable table is disposed below the dispensing mechanism 102, and an object to which a reagent is dispensed is placed on the XY table 104. The XY table 104 is attached to the Y drive mechanism 104Y that drives the surface that supports the object in the direction perpendicular to the drawing sheet (Y direction) and the Y drive mechanism 104Y. And an X drive mechanism 104X for driving in the direction (X direction). The object support surface of the XY table 104 is moved in the Y direction and the X direction within the horizontal plane by the Y drive mechanism 104Y and the X drive mechanism 104X, and the object placed on the support surface is moved by the dispensing mechanism 102. Position below the nozzle.
The imaging device 106 is, for example, a CCD camera, and the imaging device 106 is attached obliquely above the tip of the nozzle of the dispensing mechanism 102 so that the light receiving shaft 110 of the imaging device 106 has an angle θ from the horizontal direction. The imaging device 106 is set to capture an image of a droplet formed at the nozzle tip of the dispensing mechanism 102.
The position on the plane where the imaging device 106 is attached is within the movement range of the XY table 104, but does not come into contact with the imaging device 106 even if the XY table 104 moves within the movement range. As described above, the mounting position of the imaging device 106 is set above the XY table 104.
There is an appropriate range for the angle θ between the light receiving axis 110 of the imaging device 106 and the horizontal plane. θ is at least large enough that the imaging device 106 does not interfere with the XY table 104 and does not interfere with capturing an image of a sample or reagent droplet formed at the nozzle tip of the dispensing mechanism 102. Is set. As such an angle θ, about 15 to 45 degrees is appropriate.
A light source 108 is attached above the XY table 104 at a position opposite to the imaging device 106 across the nozzle tip, so that the imaging device 106 can image with transmitted light.
As shown in FIG. 6, the light 112 emitted from the light source 8 is reflected by the surface of the object 114 on the XY table 104, and the droplet 122 formed at the tip of the nozzle 120 of the dispensing mechanism 102. The relative positional relationship between the light source 108, the imaging device 106, the nozzle 120, and the object 114 is set so as to enter the imaging device 106 along the light receiving axis 110 of the imaging device 106.
The depth of field of the imaging device 106 is preferably set so that the surface of the droplet 122 at the tip of the nozzle and the surface of the object 114 therebelow are also focused. As a result, the state of the droplet 122 at the tip of the nozzle and the state of the surface of the object 114 can be simultaneously captured as an image and monitored.
As an application of this dispensing apparatus, for example, an apparatus that dispenses a reagent to a solid phase such as a PVDF (polyvinylidene difluoride) membrane can be cited. A spot developed by thin layer chromatography is transferred to the PVDF membrane, and a reagent is dispensed in order to develop the color of the spot. As such a solid phase, nitrocellulose, nylon (registered trademark), or the like can be used in addition to the PVDF membrane.
The XY table 4 is moved to repeat the dispensing of the reagent and sample from the nozzle tip at a number of dispensing positions. At that time, when monitoring the shape of the droplet dropped from the nozzle tip, the timing at which the imaging device 106 captures an image from the start of dropping of the droplet 122 from the nozzle 120 is made constant so that the droplets are the same. It can be processed as a timing image.
As one method for realizing such image capture, a strobe is used as the light source 108, the imaging device 106 continuously captures images, and the time from the start of dropping from the nozzle 120 to the lighting of the strobe is constant. Can be mentioned. This makes it easy to monitor the shape of the droplet by imaging a large number of droplets at the same timing. Such a droplet shape monitor controls the voltage applied to the piezo element of the dispensing mechanism that dispenses the sample and the reagent and the opening and closing of the valve so that the shape of the repeated droplets becomes constant. Can be used.
The light source 108 is not limited to a strobe, and may emit light continuously. In that case, the imaging device 106 may control to capture an image at a certain time from the start of dropping the droplet 122.
FIG. 7 schematically shows a dispensing apparatus according to an embodiment of the sixth aspect. Reference numeral 201 denotes a piezo chip dispensing mechanism, which is provided with a piezo chip as shown in FIG. Reference numeral 203 denotes liquid droplets ejected from the piezo chip, and is dispensed to a target 205 such as a container or a plate held under the dispensing mechanism 201. In order to capture and monitor the image of the discharge unit at the tip of the dispensing mechanism 201, a CCD camera 204 is disposed as an imaging device. The CCD camera 204 can simultaneously image the ejected droplet 203 as well as the state of the ejection unit. The imaging device is not limited to a CCD camera, and other cameras may be used.
The CCD camera 204 images the tip of the dispensing mechanism 1 from the horizontal direction. Although the image may be taken from an obliquely upward direction with an inclination from the horizontal, the image is preferably taken from the horizontal direction in order to more accurately monitor the state of the tip of the discharge unit.
In order to capture an image of the tip of the dispensing mechanism 201 more accurately, in this embodiment, the CCD is placed on the optical axis of the CCD camera 204 with the tip of the dispensing mechanism 1 sandwiched so that the image can be captured with transmitted light. The light source 2 is disposed on the side opposite to the camera 204. The light source 202 may emit light that is temporally continuous, but a strobe is used in this embodiment. In the case of a strobe, it can be set to emit light in synchronization with the timing at which the droplet 203 is discharged from the dispensing mechanism 201. In this case, even if the camera 204 is continuously operated, the strobe 202 A clear image is captured only when is emitted. The clear image is obtained by capturing the images of the sequentially ejected droplets 203 at the same timing, so that information like a still image can be obtained. Therefore, it is convenient for monitoring the state of the droplet 203.
Reference numeral 206 denotes a dispensing control unit which discharges by applying a voltage to the piezo element of the dispensing mechanism 201. In addition, the light emission timing of the strobe 202 is synchronized with the timing of voltage application to the piezo elements of the dispensing mechanism 201 by the dispensing control unit 206 so that the light is emitted after a certain period of droplet discharge from the dispensing mechanism 201. Be controlled.
A pressure control mechanism 208 holds the discharge liquid such as a sample or a reagent filled in a reservoir, which is a space for filling the liquid in the dispensing mechanism 201, at a constant pressure. The pressure control mechanism 208 is also used in the present invention to prepare the liquid level at the tip of the discharge unit before the start of the discharge operation.
A control computer 207 controls the dispensing control unit 206 to control the dispensing operation, and includes a storage device that stores an image captured by the CCD camera 204. The liquid is stored in the reservoir of the piezo chip in the dispensing mechanism 201. Compare the image stored in the storage device with the image of the discharge part before filling the liquid and the image after filling the reservoir with the liquid, and the difference between the image before the liquid filling after the liquid appears from the discharge part A function of a control device that controls the pressure control mechanism 208 so as to move backward until it disappears is also realized.
FIG. 8 schematically shows an example of a piezo chip in the dispensing mechanism 201.
The piezo chip is provided with a flow path leading from the reservoir 232 to the hole of the discharge section 230 at the tip, and the liquid in the reservoir 232 or the flow path is pressed by the drive section 234 including a piezo element from the discharge section 230. Discharge the liquid. The driving of the piezo element is controlled by the dispensing control unit 6. A pressure control mechanism 208 is connected to the reservoir 232 so that a constant pressure state is maintained even when the sample or reagent in the reservoir 232 decreases.
The parameter for controlling the driving of the piezo element by the dispensing control unit 206 is the magnitude of the applied voltage to the piezo element, the applied voltage rise time, the applied time, the applied voltage fall time, or at least one of them. .
With reference to FIG. 9, the operation of adjusting the liquid level state at the tip of the discharge portion before the start of the dispensing operation in this embodiment will be described. This embodiment describes the case where the control computer 7 automatically adjusts, but this operation can also be performed manually while viewing the image of the discharge portion tip.
Before starting dispensing, first perform solution filling. The tip of the piezo chip can be confirmed by capturing an image from the CCD camera 204.
When the control computer 7 instructs to fill the piezo chip with the solution, the control computer 207 first acquires and holds an image of the tip of the piezo chip before filling with the CCD camera 204. This image is defined as an image (a).
Next, the control computer 207 controls the pressure control mechanism 208 to pressurize the solution and push it out toward the tip of the piezo chip. At this time, the control computer 7 periodically captures the image of the tip of the piezo chip using the CCD camera 204, and obtains a difference from the previously taken image (a) before filling. If there is a change in the difference, the solution has come out of the tip of the piezo chip, so when the state is detected, the pressure control is fed back. In the meantime, the control computer 207 periodically captures the image of the tip of the piezo chip using the CCD camera 204, and continues the operation of taking the difference from the previously taken image (a) before filling. The feedback is periodically applied to the pressure control, and when it is detected from the difference between the images that the excess liquid amount is lost, the feedback is stopped and the state is maintained.
FIG. 10 schematically shows an apparatus to which the method of one embodiment of the seventh living surface is applied. Using a piezo-type dispensing apparatus, the size of a droplet is automatically obtained, This shows a case where the control to keep constant is automatically performed.
In order to capture an image of the droplet 306 ejected from the piezo chip 302, a CCD camera 320 directed to the droplet 6 ejected from the piezo chip 302 is provided as an imaging device. An image storage unit 322 stores an image captured by the CCD camera 320. The image capture by the CCD camera 320 is synchronized with the timing at which the droplet 6 is ejected or is captured asynchronously.
Reference numeral 324 denotes an image processing unit, and the image processing unit 324 performs image processing such as binarization and contour extraction on the image stored in the image storage unit 322 to reduce the diameter and radius of the droplet. Find and calculate the dispense volume. In the case of an image captured by the image processing unit 324 in synchronization with droplet ejection by the CCD camera 320, each droplet is an image at the same time from ejection. When the images are captured asynchronously, a plurality of images are captured in time series by the CCD camera 320 for one image. Among them, the image processing unit 324 adopts an image of a droplet that passes through the same location for each droplet. To process the image.
Reference numeral 326 denotes an image processing unit that displays an image of a droplet subjected to image processing. In addition, the dispensing amount obtained by image processing by the image processing unit 324 is sent to the piezo dispensing control unit 304a. The piezo dispensing control unit 304a controls the driving of the piezo chip 302 so that the dispensed amount (size of the droplet 6) to be discharged next becomes equal to a preset set value.
For example, as shown in FIG. 11, the piezo chip 302 discharges liquid from the discharge unit 330 by pressing a liquid reservoir 332 connected to the hole of the discharge unit 330 at the tip by a drive unit 334 provided with a piezo element. To do. A pressure unit (not shown) is connected to the liquid reservoir 332 so that a constant pressure state is maintained even when the sample or reagent in the liquid reservoir 332 decreases.
As shown in FIG. 12, the parameters for controlling the driving of the piezo chip 2 by the piezo dispensing control unit 304a are the magnitude V _{0 of} the applied voltage to the piezo element, the applied voltage rise time t ₁ , and the applied time t _2. , All or at least one of the applied voltage fall times t ₃ .
FIG. 13 summarizes the operation of this embodiment.
The driving of the piezo chip 302 is controlled by a preset piezo chip control parameter, and the droplet 6 is discharged. The CCD camera 320 captures the image of the droplet 306 in synchronization with or asynchronously with the ejection of the droplet, and stores it in the image storage unit 322. The image processing unit 324 performs image processing such as binarization and contour extraction on the image stored in the image storage unit 322, calculates the size such as the diameter and radius of the droplet, and calculates the dispensing amount. To do. When the dispensing amount is a predetermined value, the piezo dispensing control unit 304a repeats driving of the piezo chip 302 without changing the piezo chip control parameter. However, when the dispensing amount is not a predetermined value, the piezo chip control parameter is changed, and the piezo dispensing control unit 304a sets the piezo chip 302 so that the dispensing amount discharged from the next becomes equal to the predetermined value. Control the drive.
FIG. 14 schematically shows an apparatus to which the method of another embodiment is applied, and uses a syringe pump dispenser to automatically determine the size of the droplet and control it to be constant. This is a case where it is automatically performed.
The discharge of the droplet 6 from the probe 312 connected to the syringe pump 310 is performed by controlling and driving the motor 14 that operates the syringe pump 310 by the syringe dispensing control unit 318a. A disposable tip 316 is provided at the tip of the probe 312.
The CCD camera 320 that captures the image of the droplet 306, the image storage unit 322, the image processing unit 324, and the image display unit 326 are the same as those shown in FIG.
The syringe dispensing control unit 318a takes in data relating to the size of the droplet such as the diameter and radius of the droplet 306 from the image processing unit 324, and the setting value in which the size of the droplet 306 to be discharged next is set in advance. The drive of the motor 314 is controlled so as to be equal to.
The parameter that the syringe dispensing control unit 318a controls the driving of the motor 314 is all or at least one of the stroke, speed, and acceleration of the plunger.
As shown in FIG. 15, when dispensing a droplet 306 of several hundreds nL to several μL into a container 340 or a plate 342 by a syringe method, the tip of the disposable tip 316 (the disposable tip 316 is used). If not, the droplet 306 hangs in a ball shape at the tip of the probe 312, and the droplet 6 in that state is captured as an image by the CCD camera 320, and an image such as binarization or contour extraction is captured by the image processing unit 322. The process is performed, the diameter or radius of the droplet is determined, and the dispensing volume is calculated. When controlling the driving of the motor 14, the syringe dispensing control unit 318a returns the plunger if the amount of liquid corresponding to the obtained droplet 306 size is larger than the target dispensing amount, and pushes the plunger if not enough. Thus, the dispensing amount is controlled in real time, and the droplet 306 of the probe or the disposable tip is dispensed into the container 340 or the plate 342.
When the present invention is applied to a dispensing method using a syringe pump, the same applies to dispensing using a disposable tip as the tip 316 and a tip holding a filter or carrier in the tip. Can do.

  The liquid dispensing apparatus of the present invention is used, for example, as a method and apparatus for dispensing a reagent or the like on a membrane in order to use a substance developed on a membrane and solid-phased as a sample such as mass spectrometry. can do.

Claims (4)

A piezo chip that has a downward opening and discharges liquid droplets from the discharge unit by pressing a liquid filled in the space connected to the discharge unit with a drive unit having a piezo element; In a dispensing method in a dispensing unit including a pressure control mechanism capable of adjusting the pressure state of the filled liquid and an imaging device that captures an image of the discharge unit,
The image of the ejection unit before filling the space with the liquid is captured and stored by the imaging device,
As a preparatory step before starting the dispensing operation from the piezo chip, after filling the space with the liquid, the image pickup device captures the image of the discharge unit and obtains the difference from the image before the liquid filling. And a step of reversing the liquid until the difference from the image before filling the liquid disappears after the liquid appears from the discharge part by controlling the pressure control mechanism. The dispensing method according to claim 1, wherein the pressure control mechanism is automatically controlled based on an image captured by the imaging device. Dispensing with a piezo chip that has a downward opening and discharges liquid droplets from the discharge part by pressing the liquid filled in the space connected to the discharge part with a drive part equipped with a piezo element. Unit,
A pressure control mechanism capable of adjusting the pressure state of the liquid filled in the space;
An imaging device that captures an image of the ejection unit;
A storage device for storing an image captured by the imaging device;
After comparing the image stored in the storage device with the image of the discharge unit before filling the space with the liquid and the image after filling the space with the liquid, and after the liquid appears from the discharge unit, the liquid A dispensing device comprising: a control device that controls the pressure control mechanism so as to move backward until there is no difference from the image before filling. The dispensing device according to claim 3, wherein the imaging device is installed so as to capture an image of the discharge unit from a horizontal direction.

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