JP4722551B2 - Solution discharge amount evaluation apparatus and method - Google Patents

Description

  The present invention relates to a technique for measuring a very small amount of discharge solution, and in particular, a solution discharge amount evaluation apparatus for obtaining a discharge amount of a very small amount of discharge solution containing an electrochemically or electrically active substance with high accuracy. And a method.

In recent years, along with the development of photolithography technology, processing of a size of several to several hundreds of micrometers is performed on a solid surface of metal, semiconductor, glass, resin, etc., or a device having a fine structure is made using these as materials. Microfabrication technology is being implemented.
In addition, with the advent of the nanotechnology era, technology for processing micrometer or smaller, for example, nanometer-level sizes by using electron beams etc. is also moving from the research level to the practical level, A nanofabrication technique for producing a structure having a nanometer-scale size by controlling a single molecule is also known.

  On the other hand, a technique called nanobio, which applies these microfabrication and nanofabrication techniques to biotechnology such as biological measurement, has been made. It is most efficient to use the advantages of living organisms in in vivo measurement using this nanobio technology. The advantages include, for example, high specificity and high reactivity of biological reactions, specifically, antigen-antibody reaction, enzyme reaction, and selective binding of complementary DNA (deoxyribonucleic acid). As a result, it is possible to provide biospecificity and high bioreactivity by processing a chip processed using microfabrication and nanofabrication technologies, and to produce biochips for biological measurement. It is one of the important technologies for technology.

  However, since most reactions in the living body are reactions in a solution, a technique for controlling the solution is indispensable in order to use the biological reaction. Further, in order to process a microfabricated device so that it can be measured by a living body, a technique for accurately handling a very small amount of solution is required. Furthermore, since reagents such as enzymes and antibodies are very expensive, a technique for efficiently using a trace amount of solution without wasting it is also necessary.

  Considering a specific liquid volume, a 1 millimeter cubic solution corresponds to 1 microliter, a 100 micrometer cube corresponds to 1 nanoliter, a 10 micrometer cube corresponds to 1 picoliter, and a 1 micrometer cube corresponds to 1 femtoliter. That is, this indicates that it is necessary to manipulate nanoliter, picoliter, and femtoliter solutions when a device manufactured by the microfabrication technology is applied to the bio field.

  Until now, there is a DNA chip as an example in which the microfabrication technology is applied to biological measurement. A DNA chip is a microelement used for analyzing DNA extracted from a living body, and is manufactured by controlling a small amount of solution containing DNA. For this production, an ink ejection technique of an ink jet printer or the like is used, and it is performed by ejecting a solution containing different types of DNAs on a micrometer-sized space.

At the laboratory level, when a pipetter, which is the most versatile method, is used, a solution of about 1 microliter can be handled with relatively high repeatability. Furthermore, when the amount of liquid is smaller than that, attempts have been made to discharge a trace amount of solution using various dispensers using a syringe pump, a liquid transport pump, a piezoelectric actuator, and the like (see Patent Document 1). On the other hand, methods for measuring the discharge amount include a change in the weight of the solution tank, a change in the liquid level, a change in the pressure of the head, and a solenoid valve open / close time measurement by a timer. It has been known. A technique for measuring the concentration of a very small amount of solution using an electrochemical method is also known (Non-Patent Document 1).
Patent No. 3621041 S. Neugebauer, et al., "Analysis in ultrasmall volumes: Microdispensing of picoliter droplets and analysis without protection from evaporation," Analytical Chemistry, vol. 76, no. 2, pp. 458-462, January 15, 2004.

  However, conventional methods do not take into account the amount of liquid lost due to adhesion to the liquid tank or chip or liquid dripping, so the amount of liquid discharged on the substrate cannot be measured accurately. There was a problem. Further, since it was assumed that a small amount of solution was discharged using a large amount of solution, there was a problem that it could not be used when a very small amount of solution was discharged by inhaling a small amount of solution. Furthermore, in order to measure the discharge amount or to measure the accuracy of the discharge amount, a very large and expensive device is required, and a large amount of reagent is required to keep the state of the device optimal. There was a problem that had to be thrown away. Therefore, it has been very difficult to use these techniques at the laboratory level.

Moreover, since the technique described in Patent Document 1 uses a commercially available electronic balance, there is a problem that the amount of solution can be measured only up to about 1 microgram, that is, about 1 nanoliter. In addition, since specific equipment such as a windshield that automatically opens and closes is required when performing the measurement, it has been difficult to apply the measurement to a very small amount of solution.
In order to measure the discharge amount of a small amount of solution, there is an attempt to calculate the discharge amount of the solution by drying after discharging the solution and measuring the diameter of the dot indicating the size of the region where the solution was present. However, there are few cases where the diameter of the dots formed by drying the discharge solution becomes a perfect circle, and it is difficult to obtain an accurate discharge amount of the solution.
Further, the technique described in Non-Patent Document 1 has a problem that although the concentration of the solution can be measured, the discharge amount of the solution cannot be measured.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a solution discharge amount evaluation apparatus and method that can accurately evaluate a very small amount of solution.

The present invention has been made to solve the above-described problems, and one aspect of the present invention is a solution discharge amount evaluation apparatus for obtaining a discharge amount of a discharge solution, which is provided on an electrode formed on a substrate. A discharge means for discharging the discharge solution; a drying means for drying the discharge solution discharged by the discharge means; a current value measuring means for measuring a current value of a current flowing through the electrode; and a discharge amount of the discharge solution; A storage means for storing the current value flowing through the electrode when the discharge solution of the discharge amount is used, a current value measured by the current value measurement means, and a current value stored by the storage means A solution discharge amount evaluation device comprising discharge amount calculation means for obtaining a discharge amount of the discharge solution discharged by the discharge means by comparison .

Moreover, one aspect of the present invention is the above-described solution discharge amount evaluation device, wherein the current value measuring means measures the current value of the current flowing through the electrode by immersing the electrode in a measurement solution. It shall be the feature.

Moreover, one aspect of the present invention is the above-described solution discharge amount evaluation device, wherein the current value measuring means measures the current value by using a scanning electrochemical microscope.

One embodiment of the present invention is a solution discharge amount evaluation method for obtaining a discharge amount of a discharge solution, which includes a discharge containing an electrochemically or electrically active substance on an electrode formed on a substrate. A first step of discharging the solution; a second step of drying the discharge solution discharged in the first step; a third step of measuring a current value of a current flowing through the electrode ; By comparing the current value measured in the third step with the current value of the database that correlates the discharge amount and the current value that flows through the electrode when using the discharge solution of the discharge amount, And a fourth step of determining a discharge amount of the discharge solution discharged in the first step .

Further, one aspect of the present invention is the solution discharge amount evaluation method described above, wherein the third step includes immersing the electrode in a measurement solution and measuring a current value of a current flowing through the electrode. It shall be the feature.

Another aspect of the present invention is the above-described solution discharge amount evaluation method, wherein a discharge solution containing an enzyme or osmium is used as the discharge solution containing the electrochemically or electrically active substance. It shall be the.

Another embodiment of the present invention is the above-described solution discharge amount evaluation method, the third step, by using the scanning electrochemical microscope, characterized by measuring the current value .

In the present invention, after discharging the discharge solution onto the electrode formed on the substrate and drying it, the discharge amount of the discharge solution is evaluated by measuring the current value of the current flowing through the electrode in the measurement solution. I did it.
Thereby, the discharge amount of a very small amount of discharge solution smaller than microliters can be calculated with high accuracy without considering that the amount of discharged discharge solution changes due to evaporation or the like.

FIG. 1 is a flowchart showing a processing flow according to the solution discharge amount evaluation method of the embodiment of the present invention. In this embodiment, a very small amount of solution is discharged onto the substrate, and the discharge amount is evaluated. FIG. 2A is a plan view showing the configuration of the substrate according to the present embodiment. On the substrate 10a, a total of 64 working electrodes 1 of 8 rows × 8 columns are formed in a lattice pattern. Each working electrode 1 is formed with a lead wire 2 for electrical connection to the outside so as not to come into contact with a lead wire connected to another working electrode. As shown in FIG. 2B, the discharge amount is evaluated by discharging a very small amount of the liquid droplet 3 on each working electrode 1. The droplet 3 contains an electrochemically or electrically active substance. As the substrate 10a, a transparent substrate such as glass or acrylic resin can be used. If a transparent substrate is used in this way, the discharge amount can be evaluated while observing the state of the solution discharged from the bottom of the substrate with an inverted microscope.
As the material of the working electrode 1, a metal such as gold, platinum, tungsten, a metal oxide, carbon, an organic material, a conductive material such as a conductive polymer, a semiconductor material, or the like can be used. If necessary, the working electrode 1 may be produced by combining these materials.

  Returning to FIG. 1, a solution containing an electrochemically or electrically active substance is discharged onto each working electrode formed on the substrate (step S01). Here, examples of the electrochemically or electrically active substance include electron transfer mediators such as osmium bipyridyl, rubidium bipyridyl, benzophenone, anthracene, ferrocene complex, and pyricyan complex, conductive polymers such as polypyrrole, and metal fine particles. Metal oxide particles, carbon fine particles, metal paste, carbon paste, and the like can be used.

Next, the solution discharged on the working electrode of the substrate is dried (step S02). Then, a cylindrical enclosure or the like is installed on the working electrode of the substrate, and the measurement solution is injected into the enclosure (step S03). Next, by setting the reference electrode and the counter electrode in the measurement solution, the current value of the current flowing between the working electrode and the counter electrode is measured based on the potential of the reference electrode (step S04). Thereby, the data of the current value of the current flowing between the counter electrode and each working electrode can be acquired.
By performing the processes in steps S01 to S04 on a very small amount of solution whose discharge amount has been measured in advance, the solution amount and current value data are stored in the database in association with each other. Then, the current value data is obtained by performing the above-described steps S01 to S04 on the solution whose discharge amount is unknown, and the current value data and the current value data stored in the database are obtained. Comparison is made (step S05), and the corresponding solution amount is determined (step S06).

  According to the solution discharge amount evaluation method described above, a solution containing an electrochemically or electrically active substance is discharged onto each electrode of a working electrode in which a plurality of electrodes are arranged in a grid pattern, and after drying, in an aqueous solution By measuring the value of the current flowing between the working electrode and the counter electrode, the discharge amount of the solution discharged onto each working electrode can be evaluated.

  In the above-described embodiment, the case where a solution containing an electrochemically or electrically active substance is used has been described. However, other than this, the reaction product seems to be electrochemically or electrically active. A solution containing various enzymes can also be used. In this case, the discharge amount can be calculated by discharging and drying the solution containing the enzyme and measuring the current value while adding the substrate with which the enzyme reacts to the solution.

In the present embodiment, the case where the substrate as shown in FIG. 2A is used has been described, but the substrate 10b as shown in FIG. 3A may be used. This substrate is composed of 24 working electrodes in total, 4 rows × 6 examples. The working electrode 1a and the working electrode 1b are formed to be a pair. Moreover, the lead wire 2 for electrically connecting with the exterior is formed in each working electrode 1a, 1b so that it may not contact the lead wire connected with another electrode part.
In this case, a droplet 3 of a solution containing an electrochemically or electrically active substance is ejected onto a pair of working electrodes 1a and 1b formed on the substrate 10b as shown in FIG. Step S01 in FIG. Next, the solution discharged onto the working electrodes 1a and 1b of the substrate 10b is dried (step S02 in FIG. 1).

Next, a cylindrical enclosure or the like is installed on the substrate 10b, and the measurement solution is injected into the enclosure (step S03 in FIG. 1). Then, by setting the reference electrode in the measurement solution, the current value of the current flowing between the working electrode 1a and the working electrode 1b is measured based on the potential of the reference electrode (step S04 in FIG. 1). Thereby, the data of the current value of the current flowing between the working electrode 1a and the working electrode 1b is acquired.
By performing the processes in steps S01 to S04 on a solution whose discharge amount is known in advance, the solution amount and current value data are stored in the database in association with each other. Then, the current value data is obtained by performing the above-described steps S01 to S04 on the solution whose discharge amount is unknown, and the current value data and the current value data stored in the database are obtained. By comparing (step S05 in FIG. 1), the corresponding discharge amount is determined (step S06 in FIG. 1).

On the other hand, depending on the type of substance contained in the solution to be discharged, a simpler solution discharge amount evaluation method can be used. For example, after discharging the solution onto the working electrodes 1a and 1b as shown in FIG. 3 and drying the solution, it was discharged by measuring the current value of the current flowing between the electrodes in the air with an ammeter or the like. The discharge amount of the solution can be evaluated.
Further, if measurement is performed using four electrodes, more accurate quantification is possible as compared with the case where measurement is performed using two electrodes of the working electrodes 1a and 1b.

  In the above description, the case where the discharge amount of the solution to be discharged is obtained using a solution containing an electrochemically or electrically active substance is described. However, a solution containing an optically active substance is used. May be. In this case, the discharge amount of the solution discharged on each working electrode can be evaluated by measuring the absorbance, fluorescence intensity, or emission intensity on each working electrode.

  Next, a solution discharge amount evaluation method according to the first embodiment of the present invention will be described. In this example, the amount of solution discharged was evaluated using the substrate 10a described in FIG. As the material of the working electrode, indium tin oxide was used. As the working electrode, one having a square side of 20 micrometers was used, and the distance between the working electrodes was set to 60 micrometers. On each working electrode, a polymer solution containing osmium bipyridyl was used as a solution containing an electrochemically or electrically active substance. After discharging the solution onto each working electrode, it was dried at 4 ° C. overnight. Then, as shown in FIG. 4, an enclosure 8 and a reference electrode 7 were installed on the substrate 1, and a phosphate buffer solution was injected into the enclosure 8 as a measurement solution. Then, the current value of the current flowing between each working electrode 1 and the counter electrode 4 was measured using a multipotentiostat 5 that flows current between each working electrode 1 and the counter electrode 4. The measured current value data was recorded on a PC (Personal Computer) 6. In FIG. 4, the portion indicated by A <b> 1 is an enlarged perspective view of the bottom of the enclosure 8, and the state in which the liquid droplet 3 of the solution is discharged onto the working electrode 1 formed in a lattice shape. Show.

  FIG. 5 shows cyclic voltammogram data, which is current value data measured by the multipotentiostat 5. As shown in the figure, data of a plurality of convex curves having different heights in the vertical direction in the vertical axis direction with current 0 (pA) as a reference was obtained. Each curve represents a current value of a current flowing through each working electrode, and the magnitude of the peak area of each curve corresponds to the magnitude of the discharge amount on each working electrode. By examining the variation (standard deviation) of the area, the accuracy of the discharge amount can be evaluated.

  Here, if a cyclic voltammogram is measured using a polymer solution containing a known amount (1 to 3 microliters) of osmium bipyridyl in advance, a calibration curve is created and stored as a database on PC-6, the discharge amount Measures the current value of the unknown solution and determines the discharge amount based on the data stored in the database, thereby quantifying the discharge amount (100 to 500 picoliters) of the solution discharged onto each working electrode. I was able to.

  The electrochemical reaction of osmium bipyridyl is very fast, and indium tin oxide is electrochemically inactive in phosphate buffer solution. Therefore, if the working electrode shown in FIG. Even if it is smaller than the area of the working electrode 1, the discharge amount can be evaluated. Further, as long as it does not reach the adjacent working electrode 1, evaluation was possible even when the discharge area of the solution droplet 3 was larger than the electrode area of the working electrode 1, as shown in FIG. 6. For example, it is possible to evaluate the accuracy of the amount of solution on the working electrode 1 at the nanoliter or picoliter level or higher. Further, if the distance between the working electrodes 1 is further increased, it is possible to evaluate a solution having a larger discharge amount.

In the present embodiment, indium tin oxide is used as the material of the working electrode 1, but other metals, metal oxides, semiconductor materials, carbon, and the like can also be used. In this embodiment, the working electrode 1 has a square shape, but the shape and size are not limited as long as the electrode area of each working electrode is the same.
In this example, a polymer solution containing osmium bipyridyl was used as a solution containing an electrochemically or electrically active substance, but a chemical reaction proceeds by changing the potential between the working electrode 1 and the counter electrode. Such materials may be used.
In the above description, a case has been described in which a plurality of working electrodes 1 are formed on a substrate and a multipotentiostat 5 that measures the current value of the current flowing through each working electrode 1 at a time is used. The solution discharge amount may be evaluated using a single potentiostat that measures the current value of the current flowing through the working electrode 1 one by one.

  When using the substrate 10b shown in FIG. 3, a solution containing a carbon paste is used as a solution containing an electrochemically or electrically active substance, and the solution is discharged onto two adjacent working electrodes. After drying, the conductivity between the two working electrodes may be measured in the air by an electrometer or the like. In this way, it is not necessary to install an enclosure on the substrate or to inject the measurement solution into the enclosure, so that the amount of solution discharged can be evaluated by a simpler method.

  Next, a solution discharge amount evaluation method according to the second embodiment of the present invention will be described. In this example, indium tin oxide was used as the material of the working electrode as in the first example. Here, a working electrode having a square with a side of 50 micrometers and a distance between the working electrodes of 250 micrometers was used. Then, a solution containing glucose oxidase, BSA (bovine serum albumin), and glutaraldehyde was discharged onto each electrode as a solution containing an electrochemically or electrically active substance. After the solution was dried, an enclosure and a reference electrode were placed on the substrate, and a phosphate buffer solution having a pH of 7.4 was injected into the enclosure as a measurement solution. And when the value of the current flowing between the working electrode and the counter electrode was measured by chronoamperometry using a multipotentiostat, the result shown in FIG. 7 was obtained. The four curves in this figure represent the measurement results of current values at different working electrodes.

  The electrode potential was kept at 0.7 V with respect to Ag / AgCl used as the reference electrode, and glucose was 2 mmol / liter, 4 mmol / liter, 6 ml at the point of the downward triangle (▽) in FIG. It added so that it might become a millimol / liter and 8 millimol / liter. As a result, an increase in the oxidation current value of hydrogen peroxide obtained by the reaction between glucose and glucose oxidase could be observed. The change in the current value at each working electrode reflects the discharge amount of the solution discharged onto the working electrode, and it was possible to evaluate the accuracy of the discharge amount. When detecting hydrogen peroxide as a reaction product, it depends on the diffusion rate of hydrogen peroxide. Therefore, compared with the first embodiment, the discharge area of the discharge solution is made smaller than the size of the working electrode. It is desirable to fit within. However, by increasing the size of the working electrode, it is possible to evaluate a solution with a large discharge amount. For example, even when a discharge solution of nanoliter or picoliter level or higher is discharged on the working electrode, it is possible to evaluate the accuracy of the discharge amount of the discharge solution.

  In this embodiment, indium tin oxide is used as the working electrode material, but other metals, metal oxides, semiconductor materials, carbon, and the like may be used. In addition, here, the case where the shape of each working electrode is a quadrangle and has a predetermined size has been described, but the shape and size of each working electrode is not limited thereto. Further, the current value of the current flowing through each working electrode need not be measured at once using a multipotentiostat, but may be evaluated one by one using a single potentiostat.

  Next, a solution discharge amount evaluation method according to a third embodiment of the present invention will be described. In this example, a solution discharge amount evaluation apparatus as shown in FIG. 8 was used. In this solution discharge amount evaluation apparatus, the potentiostat 5 is used as in the first and second embodiments. In addition, a scanning electrochemical microscope was used, and the current value of the current flowing through the microelectrode 9 was measured while scanning the microelectrode 9 maintained at a constant potential in the vicinity of the surface of the substrate 10. In FIG. 8, a portion indicated by A <b> 2 is an enlarged perspective view of the bottom portion of the enclosure 8, and shows a state where the droplet 3 of the solution is discharged onto the substrate 10 and then dried. In this example, a solution containing osmium bipyridyl is discharged onto a glass substrate 10 in a plurality of dots, and after drying, Ag is a reference electrode 7 in a phosphate buffer solution having a pH of 7.4 as a measurement solution. The current value of the current flowing between the microelectrode 9 and the counter electrode 4 was measured when scanning was performed with a 0.1 mm diameter microelectrode 9 maintained at a potential of 0.5 V with respect to / AgCl. When the measurement result was visualized two-dimensionally, a result as shown in FIG. 9 was obtained. In FIG. 9, the current values of the currents flowing through the six working electrodes are shown in a circular shape, and the current values increase as the current values approach the center of the circular shape. The integrated value of the current value at each working electrode can be estimated as the discharge amount at each point, and the discharge amount can be evaluated.

In the present embodiment, there is no upper limit to the discharge amount of the discharge solution, and the accuracy of the discharge amount can be evaluated as long as there is no overlap between the discharge solutions. Furthermore, in the method of this embodiment, since it is not necessary to produce electrodes arranged in two dimensions, simpler quantification is possible.
Further, in this embodiment, the case where a discharge solution containing osmium bipyridyl which is an electrochemical mediator is discharged onto a substrate has been described. For example, a solution containing an enzyme is discharged onto a substrate and dried, and then reacted with the enzyme. It is also possible to run the microelectrode 9 in an aqueous solution containing the substrate to be processed. In this case, if an electrochemical mediator is applied on the electrode, more accurate measurement is possible. Moreover, although this embodiment demonstrated the case where an electric current value was measured using three electrodes (counter electrode 4, reference electrode 7, and microelectrode 9), it is not limited to such a structure. For example, when the area of the microelectrode 9 is small, the counter electrode 4 can be omitted and the current value can be measured using two electrodes (reference electrode 7 and microelectrode 9).

  Next, a solution discharge amount evaluation method according to a fourth embodiment of the present invention will be described. As in the first and second examples, a substrate on which a working electrode made of indium tin oxide was formed was used. The working electrode used was a square having a side of 50 micrometers, and the distance between the working electrodes was 250 micrometers. Here, an ethanol solution containing a carbon paste was discharged as a solution containing an electrochemically or electrically active substance on top of two adjacent working electrodes. After the solution was dried, the current value of the current I1 flowing between the two working electrodes 1a and 1b was measured in air using an ammeter 11 having a circuit configuration as shown in FIG. A result like 11 was obtained. In FIG. 11, data of five straight lines having different inclinations are obtained. Here, it was found that each working electrode exhibits different conductivity. This difference in conductivity reflects the difference in the discharge amount of the discharge solution, and the discharge amount of the discharge solution could be evaluated based on this result.

In the present embodiment, the case where the current value is measured by the two-terminal method in which the discharge solution is discharged onto the two working electrodes has been described. However, the present invention is not limited to this, and the discharge solution is discharged onto the four working electrodes. If the current value is measured by the four-terminal method, more accurate measurement is possible.
In the first to fourth embodiments described above, the discharge amount of the solution and the current value of the current flowing through the working electrode are stored in a database such as a PC in association with each other, and the solution of the unknown discharge amount is stored. By measuring the current value and referring to the database, the discharge amount of the unknown discharge solution can be calculated.

The solution discharge amount evaluation methods according to the first to fourth embodiments described above are based on a very simple principle, and the discharge amount of a small amount of discharge solution discharged onto the working electrode is measured very simply and discharged. Accuracy can be evaluated. When applying nanotechnology to biological measurement, it is indispensable to use a very small amount of an expensive biological reagent and efficiently discharge and fix it. To that end, it is necessary to operate a very small amount of discharged solution with high accuracy. However, if the solution discharge amount evaluation method according to this embodiment is used, the problem can be solved.
Further, the solution discharge amount evaluation method according to the present embodiment is extremely effective when evaluating the quality evaluation and discharge method of an apparatus for discharging a small amount of discharge solution currently being developed or marketed. It is also effective for evaluating the dispensing amount of a dispensing device when dispensing a very small amount of reagent below the nanoliter level.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes designs and the like that do not depart from the gist of the present invention.

  Evaluation of the discharge amount when a very small amount of discharge solution is discharged to a predetermined place is a technology that will become more and more necessary in the future for accurate and precise biological measurement. The apparatus and method for evaluating the amount of discharged solution of the present invention are extremely effective and highly likely to be used in the field of fusion of nanotechnology and biotechnology, which are expected to develop significantly in the future.

It is a flowchart which shows the flow of the process by the solution discharge amount evaluation method of embodiment of this invention. It is a top view which shows the structure of the board | substrate by this embodiment. It is a top view which shows the other structure of the board | substrate by this embodiment. It is the schematic which shows the structure of the solution discharge amount evaluation apparatus by this embodiment. It is a graph which shows the measurement result of the electric current value by 1st Example of this invention. It is a plane photograph which shows the mode of the board | substrate used in the present Example. It is a graph which shows the measurement result of the electric current value by 2nd Example of this invention. It is the schematic which shows the structure of the solution discharge amount evaluation apparatus by the 3rd Example of this invention. It is a two-dimensional image which shows the measurement result of the electric current value by a present Example. It is a figure which shows the circuit structure used in the 4th Example of this invention. It is a graph which shows the measurement result of the electric current value by a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Working electrode, 2 ... Lead wire, 3 ... Droplet, 4 ... Counter electrode, 5 ... Multipotentiostat, 6 ... PC, 7 ... Reference electrode, 8 ... Enclosure, 9 ... Microelectrode, 10a, 10b ... Substrate, 11 ... Ammeter

Claims (7)

A solution discharge amount evaluation device for obtaining a discharge amount of a discharge solution,
A discharge means for discharging a discharge solution onto an electrode formed on the substrate;
Drying means for drying the discharge solution discharged by the discharge means;
Current value measuring means for measuring a current value of a current flowing through the electrode;
Storage means for storing a discharge amount of the discharge solution and a current value flowing through the electrode when using the discharge solution of the discharge amount;
A discharge amount calculation means for obtaining a discharge amount of the discharge solution discharged by the discharge means by comparing the current value measured by the current value measurement means and the current value stored by the storage means; An apparatus for evaluating a solution discharge amount.   The solution discharge amount evaluation apparatus according to claim 1, wherein the current value measuring unit measures a current value of a current flowing through the electrode by immersing the electrode in a measurement solution. Said current value measuring means, scanning by using an electrochemical microscope, the solution discharge amount evaluation device according to claim 1 or 2, characterized by measuring the current value. A solution discharge amount evaluation method for determining a discharge amount of a discharge solution,
A first step of discharging a discharge solution containing an electrochemically or electrically active substance onto an electrode formed on the substrate;
A second step of drying the discharged solution discharged in the first step;
A third step of measuring a current value of a current flowing through the electrode;
The current value of the database in which the discharge amount of the discharge solution and the current value flowing through the electrode when the discharge solution of the discharge amount is used is compared with the current value measured in the third step. And a fourth step of obtaining a discharge amount of the discharge solution discharged in the first step . The solution ejection amount evaluation method according to claim 4 , wherein the third step includes immersing the electrode in a measurement solution and measuring a current value of a current flowing through the electrode. 6. The solution discharge amount evaluation method according to claim 4 , wherein a discharge solution containing an enzyme or osmium is used as the discharge solution containing the electrochemically or electrically active substance. The third step, by using the scanning electrochemical microscope, the solution discharge amount evaluation method according to any one of claims 4-6, characterized by measuring the current value.

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