JP2013238399A - Sensor system and measuring method of detection object using the sensor system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor system capable of high-speed and high-sensitive measurement with a simple structure.SOLUTION: A sensor system 1 includes an enzyme sensor 10 that detects a substance contained in a predetermined sample as a detection object and inhibiting the activity of enzyme. The sensor system 1 determines the density of the detection object based on a ratio between a first response ratio, which is a ratio between a first reference side response value obtained before bringing a detection sensor part into contact with the sample and a first detection side response value, and a second response ratio, which is a ratio between a second reference side response value obtained after bringing the detection sensor part into contact with the sample and a second detection side response value. Here, the first reference side response value and the second reference side response value are output values output by a reference sensor part after a waiting time has elapsed since the output value of the reference sensor part due to the contact with the substrate has exceeded a response detection threshold value; the first detection side response value and the second detection side response value are output values output by the detection sensor part after a waiting time has elapsed since the output value of the detection sensor part due to the contact with the substrate has exceeded a response detection threshold value.

Description

  The present invention relates to a sensor system and a detection target substance measuring method using the sensor system.

  Conventionally, biosensors that detect a predetermined detection target substance are known (see, for example, Patent Documents 1 to 5). Specifically, as such a sensor, for example, an organophosphorus pesticide or a carbamate pesticide in a food by utilizing the activity of an organophosphorus pesticide, a carbamate pesticide or the like that inhibits the activity of an enzyme such as cholinesterase. An enzyme sensor that detects a substance to be detected such as the like is known.

Although the enzyme sensor is excellent in sensitivity and selectivity, it is easily affected by changes in the external environment such as temperature and pH.
Therefore, for example, a correction electrode (substrate concentration detection electrode, pH electrode, temperature sensor, electrical conductivity measurement electrode) that detects a change in the atmospheric state that affects the detection result and outputs a correction electric signal is provided. Thus, there has been proposed a detected substance measuring apparatus capable of correcting the detection result (see, for example, Patent Document 6).

JP 2012-026994 A Special Table 2002-54021 Special Table 2000-500380 JP 2006-087303 A JP 2005-308720 A JP 2005-241537 A

However, in the apparatus described in Patent Document 6, in order to correct the detection result more accurately, it is necessary to obtain a plurality of types of information such as temperature and pH as information relating to changes in the atmospheric state that affect the detection result. . For this purpose, a plurality of types of correction electrodes such as a temperature sensor and a pH electrode must be provided, which is troublesome.
In addition, due to the diversification of food production areas and types, interest in food safety and security is increasing. In particular, the problem of residual agricultural chemicals has attracted a great deal of attention, and there is a demand for ensuring the safety of the presence or absence of residual agricultural chemicals in foods.
Currently, pesticide residue testing is mainly performed with detection and quantification using advanced analytical equipment such as GC / MS and ELISA, which are official methods, but these methods are specialized in complex pretreatment and operation techniques. It requires technical knowledge and technology, and the equipment is expensive, and it takes a long time for pretreatment and measurement. Therefore, it is not suitable for on-site screening that requires cost, quickness, and versatility. Therefore, it is necessary to realize a primary screening of high-performance residual agricultural chemicals that can be detected quickly even with a very small amount of agricultural chemicals, although it is a simple method.

  An object of the present invention is to provide a sensor system capable of high-speed and high-sensitivity measurement with a simple configuration and a detection target substance measurement method using the sensor system.

In order to solve the above-mentioned problem, the invention described in claim 1
In a sensor system including an enzyme sensor that detects a detection target substance contained in a predetermined sample, using a substance that inhibits the activity of the enzyme as a detection target substance.
The enzyme sensor includes a plurality of sensor units having the same configuration, and a part of the plurality of sensor units is a reference sensor unit that does not contact the sample, and the rest is a detection sensor unit that contacts the sample. ,
Storage means for storing a first response ratio calculated based on an output value of the reference sensor unit and an output value of the detection sensor unit before the detection sensor unit is brought into contact with the sample;
Obtaining means for obtaining an output value of the reference sensor unit and an output value of the detection sensor unit;
Response ratio for calculating a second response ratio based on the output value of the reference sensor unit and the output value of the detection sensor unit obtained after the detection sensor unit is brought into contact with the sample, acquired by the acquisition unit A calculation means;
Concentration determination for determining the concentration of the detection target substance contained in the sample based on the ratio between the first response ratio stored in the storage means and the second response ratio calculated by the response ratio calculation means Means, and
The first response ratio includes a first reference-side response value acquired from the reference sensor unit before the detection sensor unit is brought into contact with the sample, and the detection sensor unit before the detection sensor unit is brought into contact with the sample. And the first detection side response value acquired from
The first reference side response value is the reference sensor after a predetermined first waiting time has elapsed after the output value of the reference sensor unit exceeds a predetermined first response detection threshold value due to contact with the enzyme substrate. Output value,
The first detection-side response value is the detection sensor after a predetermined second waiting time has elapsed after the output value of the detection sensor unit exceeds a predetermined second response detection threshold value due to contact with the enzyme substrate. Output value,
The second response ratio includes the second reference-side response value acquired from the reference sensor unit after the detection sensor unit is brought into contact with the sample, and the detection sensor unit after the detection sensor unit is brought into contact with the sample. And the second detection side response value acquired from
The second reference side response value is a value of the reference sensor unit after the first waiting time has elapsed after the output value of the reference sensor unit exceeds the first response detection threshold value due to contact with the enzyme substrate. Output value,
The second detection-side response value of the detection sensor unit after the second waiting time has elapsed after the output value of the detection sensor unit exceeds the second response detection threshold value due to contact with the enzyme substrate. It is an output value.

The invention according to claim 2 is the sensor system according to claim 1,
The first reference side response value and the second reference side response value are determined by the first waiting time after the output value of the reference sensor unit exceeds the first response detection threshold due to contact with the enzyme substrate. Is the average value of the output value of the reference sensor unit after a predetermined period of time,
The first detection side response value and the second detection side response value are determined as follows: the second waiting time has elapsed after the output value of the detection sensor unit exceeds the second response detection threshold value due to contact with the enzyme substrate. After that, the output value of the detection sensor unit is an average value for a predetermined period.

The invention according to claim 3 is the sensor system according to claim 1 or 2,
A warning means is provided for giving a warning when the density determined by the density determination means exceeds a predetermined warning threshold value.

The invention according to claim 4 is the sensor system according to claim 3,
In accordance with a user operation, comprising a designation means for designating a plurality of substances as the detection target substance,
The concentration determining means determines the concentration of each of the plurality of substances, assuming that only one of the plurality of substances specified by the specifying means is included in the sample,
The warning means performs a warning when even one of the densities determined by the density determination means exceeds the warning threshold value.

The invention according to claim 5 is the sensor system according to any one of claims 1 to 4,
A support unit for detachably supporting the enzyme sensor;
The enzyme sensor is a disposable sensor.

The invention according to claim 6 is the sensor system according to any one of claims 1 to 5,
The sample is a liquid;
The enzyme sensor has a liquid reservoir around each of the plurality of sensor parts.

The invention described in claim 7
7. A method for measuring a substance to be detected, wherein a substance that inhibits the activity of an enzyme is used as a substance to be detected, and the concentration of the substance to be detected contained in a predetermined sample is measured using the sensor system according to claim 1. In
A first contact step for bringing the detection sensor unit into contact with the sample;
Next, in a state where the reference sensor unit and the detection sensor unit are arranged in the same environment, a second contact step of bringing the reference sensor unit and the detection sensor unit into contact with the enzyme substrate;
Then, the acquisition step of acquiring the output value of the reference sensor unit and the output value of the detection sensor unit by the acquisition unit while the reference sensor unit and the detection sensor unit are arranged in the same environment,
Next, a response ratio calculation step of calculating the second response ratio based on the output value of the reference sensor unit and the output value of the detection sensor unit acquired in the acquisition step by the response ratio calculation unit;
Next, based on the ratio between the first response ratio stored in the storage unit and the second response ratio calculated in the response ratio calculation step, the concentration determination unit determines the detection target substance contained in the sample. And a density determination step for determining density.

According to the present invention, the influence of changes in the external environment such as temperature and pH can be absorbed, so there is no need to keep the external environment constant by using an expensive and complicated mechanism or system, and there is a need for complicated measurement for measurement. Since no adjustment is required, simple measurement is possible.
Therefore, high-speed and high-sensitivity measurement can be performed with a simple configuration.

It is a block diagram showing an example of composition of a sensor system of an embodiment. It is a perspective view which shows an example of a structure of the enzyme sensor of embodiment. It is a figure for demonstrating an example of the principle which detects a detection target substance electrochemically with the sensor part of embodiment. It is a figure which shows the enzyme sensor with which the support part was mounted | worn. Response detection threshold (first response detection threshold, second response detection threshold), standby time (first standby time, second standby time), reference side response value (first reference side response value, second reference side response value) FIG. 6 is a diagram for explaining detection-side response values (first detection-side response value, second detection-side response value). It is a figure which shows an example of a calibration curve. It is a figure which shows the evaluation result of the sensor system comprised in the Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[Configuration of sensor system]
First, the configuration of the sensor system 1 of the present embodiment will be described.
The sensor system 1 is a system for detecting or quantifying a detection target substance contained in a sample by using an enzyme sensor 10 for detecting a detection target substance such as an organophosphorus pesticide or a carbamate pesticide.

FIG. 1 is a block diagram illustrating an example of the configuration of the sensor system 1.
As shown in FIG. 1, the sensor system 1 mainly includes an enzyme sensor 10 having a plurality of sensor units Se having the same configuration, an acquisition unit 20 connected to the sensor unit Se, and an operation unit 30 including a key group and a touch panel. And a display unit 40 including a display, and a control unit 50 connected to the acquisition unit 20, the operation unit 30, and the display unit 40.

The enzyme sensor 10 included in the sensor system 1 of the present embodiment is an electrochemical sensor that utilizes a substance to be detected such as an organophosphorus pesticide or a carbamate pesticide, by inhibiting the activity of an enzyme such as cholinesterase. It is a sensor for detecting automatically.
FIG. 2 is a perspective view showing an example of the configuration of the enzyme sensor 10.
As shown in FIG. 2, the enzyme sensor 10 is mainly formed on the substrate 11, the electrode 12 (working electrode 121, counter electrode 122 and reference electrode 123) formed on the substrate 11, and the working electrode 121. A sensor part Se composed of an electron carrier layer 13 and an enzyme layer 14 formed on the electron carrier layer 13 and a liquid reservoir forming part 15 for forming a liquid reservoir around the enzyme layer 14 of the sensor part Se. And an insulating film 16 for protecting the wiring from the electrode 12 of the sensor unit Se.
In the present embodiment, the enzyme sensor 10 includes two sensor units Se. However, the present invention is not limited to this, and the enzyme sensor 10 may be arbitrarily selected as long as the number of sensor units Se included in the enzyme sensor 10 is plural. It can be changed.

  The substrate 11 is an insulating substrate made of, for example, silicon, ceramics, glass, plastic, paper, biodegradable material (for example, microorganism-produced polyester) or the like.

The electrode 12 of the sensor unit Se is a conductive layer formed on the substrate 11 by, for example, a screen printing method.
As the working electrode 121, for example, a noble metal such as gold, platinum, copper, and aluminum, SnO ₂ , In ₂ O ₃ , WO ₃ , TiO ₂ , graphite, graphene, glassy carbon, or the like can be used.
As the counter electrode 122, for example, silver can be used in the case of the bipolar system, and silver or other metals can be used in the case of the tripolar system.
As the reference electrode 123, for example, a calomel electrode, silver / silver chloride, or the like can be used.

In addition, the electrode system of the enzyme sensor 10 is not limited to the tripolar system of the working electrode, the counter electrode, and the reference electrode, and may be a bipolar system of the working electrode and the counter electrode.
Moreover, the electrode 12 is not limited to what was formed by the screen printing method, The formation method of the electrode 12 can be changed arbitrarily arbitrarily. Specifically, the electrode 12 can be formed by, for example, a vapor deposition method, a sputtering method, or the like.

In addition, the size, shape, and configuration of the working electrode 121, the counter electrode 122, and the reference electrode 123 are not particularly limited.
Specifically, for example, these electrodes may be large electrodes used in commercially available electrolytic cells, measurement cells, etc., or may be disk electrodes, rotating ring disk electrodes, fiber electrodes, etc. For example, microelectrodes (disc electrodes, cylindrical electrodes, strip electrodes, array strip electrodes, array disc electrodes, ring electrodes, spherical electrodes, comb electrodes, pair electrodes, etc.) produced by known microfabrication techniques such as photolithography. May be. Further, the working electrode 121, the counter electrode 122, and the reference electrode 123 may have the same size, shape, and configuration, or may have different sizes, shapes, and configurations.

The enzyme layer 14 of the sensor unit Se is an enzyme whose activity is inhibited by a detection target substance such as an organophosphorus pesticide or a carbamate pesticide (specifically, a cholinesterase such as acetylcholinesterase (AChE) or butyrylcholinesterase (BChE)). ).
The enzyme layer 14 may include only one type of enzyme or a plurality of types of enzymes.
The enzyme layer 14 may contain a coenzyme for catalyzing the expression of the enzyme activity.

Here, in this embodiment, it is assumed that the enzyme is contained in the enzyme layer 14 in a state of being fixed inside the pores of the mesoporous silica.
That is, the enzyme layer 14 of this embodiment is a layer composed of mesoporous silica and an enzyme fixed inside the pores of the mesoporous silica.
In the present embodiment, the enzyme layer 14 is formed by applying a mixture of powdered mesoporous silica in which an enzyme is fixed in the pores and a binder onto the electron carrier layer 13. However, the formation method of the enzyme layer 14 is not limited to this. For example, a mesoporous silica layer is formed by applying a mixture of powdered mesoporous silica in which an enzyme is not fixed in the pores and a binder onto the electron carrier layer 13 to form the mesoporous silica layer. It is also possible to form the enzyme layer 14 by fixing the enzyme inside the pores of the porous silica layer.
Further, the shape of the mesoporous silica is not limited to a powder shape, and can be arbitrarily changed as appropriate, and may be a granular shape, a sheet shape, a bulk shape, a film shape, or the like.

In the present embodiment, the mesoporous silica contained in the enzyme layer 14 is in a powder form, and includes, for example, various metal oxides such as silicic acid and alumina, composite oxides of silicic acid and other types of metals, and the like. can do.
For example, in the production of mesoporous silica composed of silicic acid, for example, layered silicate such as kanemite, alkoxysilane, silica gel, water glass, sodium silicate and the like can be preferably used.
Specifically, the mesoporous silica is formed by, for example, mixing and reacting an inorganic material with a surfactant to form a surfactant / inorganic composite in which an inorganic skeleton is formed around the micelle of the surfactant. Then, for example, it is produced by removing the surfactant by baking at 400 ° C. to 600 ° C. or extracting with an organic solvent. Thus, the mesoporous silica has mesopore pores having the same shape as the micelles of the surfactant in the inorganic skeleton.

In the production of mesoporous silica, when a silicon-containing compound such as silicic acid is used as a starting material, for example, a layered silicate such as kanemite is formed, and micelles are inserted between the layers. The pores can be formed by connecting the non-performing layers with silicate molecules and then removing the micelles.
In the production of mesoporous silica, when a silicon-containing substance such as water glass is used as a starting material, for example, silica is formed by collecting and polymerizing silicate molecules around the micelle, and then the micelle. By removing, pores can be formed. In this case, the micelle shape is usually a columnar shape, and as a result, columnar pores are formed in the mesoporous silica.
In the mesoporous silica, the inner diameter of the pores can be controlled by changing the micelle diameter by changing the length of the alkyl chain of the surfactant in the production stage. In addition, by adding relatively hydrophobic molecules such as trimethylbenzene and tripropylbenzene together with the surfactant, the micelles can be swollen to form pores with a larger inner diameter.

The orientation of the pores in the mesoporous silica may be random, or the orientation may be controlled like an aggregate of one-dimensional silica nanochannels.
As the type of mesoporous silica, a known type such as KSW, FSM, SBA, MCM, HOM, etc., having the characteristics of uniform pore size and high porosity is adopted. Can do.

The pore size of the mesoporous silica is preferably set to such an extent that the change in the three-dimensional structure of the enzyme immobilized on the mesoporous silica can be prevented. Thereby, the three-dimensional structure of the enzyme can be maintained, and the enzyme fixed inside the pores of the mesoporous silica (that is, the enzyme contained in the enzyme layer 14) can be stabilized.
Specifically, the size of the pores of mesoporous silica is preferably about 0.5 to 2.0 times the size of the enzyme (enzyme molecule or enzyme fragment containing an active site). Is more preferably about 0.7 to 1.4 times, most preferably about the size of the enzyme. That is, the diameter of the pores of the mesoporous silica (center pore diameter) is preferably about 0.5 to 2.0 times the diameter of the enzyme, and 0.7 to 1.4 times the diameter of the enzyme. More preferably, it is about the same as the enzyme diameter. In addition, since the specific value of the center pore diameter is determined by the relationship with the diameter of the enzyme and cannot be defined uniformly, it can be set to, for example, about 1 to 50 nm.

  Here, when the enzyme forms a multimer, the size (diameter) of the enzyme can be the size (diameter) of the multimer. Here, the multimer refers to a compound in which two or more enzymes (proteins) are bonded directly or via a small molecule such as water, and the bond includes a covalent bond, an ionic bond, a hydrogen bond, Coordination bonds are included. However, the type of these bonds is not particularly limited.

The specific surface area of mesoporous silica is, for example, about 200 to 1500 m ² .
The depth of the pores of mesoporous silica is 2 nm or more. Specifically, the preferable depth range is 20 to 1000 nm, the more preferable depth range is 50 to 500 nm, and the most preferable depth range is 50 to 150 nm.
When the pitch of the pores of the mesoporous silica is defined as the distance between the centers of the pores, the preferable pitch is 2 to 500 nm, the more preferable pitch is 2 to 100 nm, and the most preferable pitch is 2-50 nm.

Thus, in this embodiment, the enzyme layer 14 is composed of mesoporous silica and an enzyme fixed inside the pores of the mesoporous silica, and the size of the pores of the mesoporous silica. Is set to 0.5 to 2.0 times the size of the enzyme.
Therefore, since the enzyme can be firmly fixed inside the pores of the mesoporous silica, the change in the three-dimensional structure of the enzyme is prevented, and the enzyme sensor 10 has excellent stability and has a long life. Can be realized.
Mesoporous silica is porous and has a very large specific surface area. Therefore, when mesoporous silica is used as a carrier, the enzyme can be immobilized at a high concentration. Furthermore, by fixing the enzyme firmly inside the pores of the mesoporous silica, the enzyme is maintained in a moderately dispersed state, so that the enzyme can be prevented from aggregating and deactivating. it can. That is, by using mesoporous silica whose pore size is set to 0.5 to 2.0 times the size of the enzyme as a carrier, the enzyme can be immobilized at a high concentration, and the enzyme Since it is possible to avoid inactivation due to aggregation, it is possible to realize the enzyme sensor 10 having excellent sensitivity.

The enzyme layer 14 may be a layer composed of a porous body other than mesoporous silica and an enzyme fixed inside the pores of the porous body. In this case, the size of the pores of the porous body is preferably about 0.5 to 2.0 times the size of the enzyme, and about 0.7 to 1.4 times the size of the enzyme. More preferably, it is most preferably approximately equal to the size of the enzyme.
The enzyme may not be fixed inside the pores of the porous body. For example, the enzyme layer 14 is a layer formed of a predetermined resin such as a polyvinyl alcohol resin and an enzyme mixed with the resin. It may be.

The electron carrier layer 13 of the sensor unit Se is a layer that includes an electron carrier for promoting the transfer of electrons between the enzyme contained in the enzyme layer 14 and the electrode 12 (specifically, the working electrode 121). is there.
In this embodiment, TCNQ (tetracyanoquinodimethane) is used as the electron carrier contained in the electron carrier layer 13, but is not limited to this, and the electrons contained in the electron carrier layer 13 are not limited thereto. The transmitter is, for example, metal phthalocyanine, Prussian blue, Meldola blue, potassium ferrocyanide, potassium ferricyanide, ferrocene, ferrocene derivative, benzoquinone, quinone derivative, osmium complex, HBT, ABTS, biophosphoric acid (violuric acid, Vio), NNS, 3-hydroxyanthranilic acid (3-HAA), 4-aminoantipyrine, HOBt, etc. may be used.
Further, the electron carrier layer 13 may contain only one type of electron carrier, or may contain a plurality of types of electron carriers.

The liquid reservoir forming part 15 is a cylindrical member surrounding the sensor part Se formed on the substrate 11. When the liquid reservoir forming portion 15 is disposed on the surface of the substrate 11 on which the sensor portion Se is formed, one opening end (lower end) side of the liquid reservoir forming portion 15 is closed. A liquid (for example, a sample liquid containing a detection target substance) can be stored.
That is, the enzyme sensor 10 has a liquid reservoir around each of the plurality of sensors Se.

Here, an example of the principle of electrochemically detecting the detection target substance by the sensor unit Se of the present embodiment will be described with reference to FIG.
When a substrate solution containing a substrate (acetylthiocholine (or butyrylthiocholine)) is dropped into the liquid reservoir forming unit 15 surrounding the sensor unit Se and the sensor unit Se is brought into contact with the substrate, as shown in FIG. The enzyme (cholinesterase) of the sensor unit Se decomposes the substrate by selective catalytic action to generate thiocholine.
Next, when the working electrode 121 is made positive and a voltage is applied between the working electrode 121 and the reference electrode 123 to apply a voltage to the substrate solution in the liquid reservoir forming part 15, thiocholine becomes an electron carrier. Electrons (e ⁻ ) are indirectly transferred to the working electrode 121 via (TCNQ) to become dithiobischoline. At this time, a current for reoxidizing the reduced electron carrier flows between the working electrode 121 and the counter electrode 122. Since the current value (hereinafter referred to as “response current value”) is proportional to the activity of the enzyme, the activity of the enzyme can be determined from the measured response current value by measuring the response current value. .

Organophosphorus pesticides bind irreversibly to enzymes such as cholinesterase, and carbamate pesticides reversibly bind to enzymes such as cholinesterase to inhibit catalytic action (activity).
Therefore, the enzyme activity in the sensor unit Se before contacting the detection target substance is compared with the enzyme activity in the sensor unit Se after contacting the detection target substance. The concentration of the detection target substance in the sample can be measured from the degree of decrease in the activity of the enzyme caused by the inhibition.

The sensor system 1 includes the same number of acquisition units 20 (two acquisition units 20 in the present embodiment) as the number of sensor units Se included in the enzyme sensor 10.
As shown in FIG. 1, the acquisition unit 20 includes a voltage application unit 21 and a current measurement unit 22, and is connected to a corresponding sensor unit Se via a connection unit 20a.
The voltage application unit 21 applies a voltage having a predetermined voltage value to the electrode 12 of the sensor unit Se. Specifically, the voltage application unit 21 is configured to apply a voltage between the working electrode 121 and the reference electrode 123.
The current measuring unit 22 is configured to measure a current value flowing through the electrode 12 of the sensor unit Se when a voltage is applied by the voltage applying unit 21 as a response current value.

In the present embodiment, the enzyme sensor 10 is a disposable sensor.
The sensor system 1 includes a support part (sensor head) 1a (see FIG. 4) that detachably supports the enzyme sensor 10, and when the enzyme sensor 10 is attached to the support part 1a, the enzyme sensor 10 is Each sensor unit Se provided is configured to be connected to the connection means 20a. Moreover, this support part 1a is connected to the acquisition part 20 via the wiring 1b.

  The operation unit 30 includes a key group and a touch panel, and is configured to output a signal corresponding to the type of pressed key and the position of the touch panel to the control unit 50.

  The display unit 40 includes a display such as a liquid crystal display, and is configured to display various information on the display based on a display signal input from the control unit 50. Here, in the present embodiment, the display of the display unit 40 is formed integrally with the touch panel of the operation unit 30 and can accept a touch operation by the user.

  The control unit 50 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like, and is configured to comprehensively control the sensor system 1.

[Detection target substance measurement method]
Next, an example of a detection target substance measurement method for measuring the concentration of the detection target substance contained in the sample using the sensor system 1 will be described.

A part of the plurality of sensor parts Se included in the enzyme sensor 10 is used as a reference sensor part that does not contact the sample, and the rest is used as a detection sensor part that contacts the sample. In the case of the present embodiment, one of the two sensor units Se arranged on the left and right sides of the enzyme sensor 10 (for example, the left sensor unit Se) is used as a reference sensor, and the other (for example, the right sensor unit Se) is used. A detection sensor is used.
In addition, the control unit 50 stores the output value (response current value) of the reference sensor unit and the output value (response current) of the reference sensor unit before the detection sensor unit is brought into contact with the sample in the storage area in the control unit 50. Value) and the first response ratio calculated based on the value. That is, the control unit 50 calculates the first calculated based on the output value (response current value) of the reference sensor unit and the output value (response current value) of the detection sensor unit before the detection sensor unit contacts the sample. It functions as a storage means for storing the response ratio.

Here, the first response ratio is acquired from the first reference side response value acquired from the reference sensor unit before contacting the detection sensor unit with the sample, and from the detection sensor unit before contacting the detection sensor unit with the sample. It is a ratio to the first detection side response value.
The first reference-side response value and the first detection-side response value can be obtained, for example, as shown in FIG.
Specifically, the first reference side response value is a predetermined first value in which an output value (response current value) of the reference sensor unit is determined in advance by contact between the reference sensor unit and the enzyme substrate included in the enzyme layer 14. This is an output value (response current value) of the reference sensor unit after a predetermined first standby time elapses after exceeding one response detection threshold.
The first detection-side response value is a predetermined second response detection in which an output value (response current value) of the detection sensor unit is determined in advance by contact between the detection sensor unit and the enzyme substrate included in the enzyme layer 14. It is an output value (response current value) of the detection sensor unit after a predetermined second waiting time that has been determined in advance from exceeding the threshold value.
Therefore, in the case of this embodiment, before bringing the detection sensor unit into contact with the sample, the substrate solution is dropped onto both the liquid reservoir forming unit 15 surrounding the reference sensor unit and the liquid reservoir forming unit 15 surrounding the detection sensor unit. Thus, it is necessary to obtain the first reference side response value and the first detection side response value from the reference sensor unit and the detection sensor unit, calculate the first response ratio, and store the first response ratio in the control unit 50.

Note that the first response detection threshold and the second response detection threshold may be the same value or different values.
Further, the length of the first waiting time and the length of the second waiting time may be the same or different.

Further, the first reference side response value and the first detection side response value may be an average value of response current values for a predetermined period as shown in FIG. 5B, for example.
Specifically, the first reference side response value is such that the output value (response current value) of the reference sensor unit exceeds the first response detection threshold due to contact between the reference sensor unit and the enzyme substrate included in the enzyme layer 14. It may be an average value of a predetermined period of the output value (response current value) of the reference sensor unit after the first standby time has elapsed.
Similarly, the first detection-side response value is obtained after the output value (response current value) of the detection sensor unit exceeds the second response detection threshold value due to contact between the detection sensor unit and the enzyme substrate included in the enzyme layer 14. It may be an average value of a predetermined period of the output value (response current value) of the detection sensor unit after the second standby time has elapsed.

First, the user creates a sample. In the present embodiment, a sample for measuring residual agricultural chemicals adhering to agricultural products is prepared.
Specifically, for example, a predetermined amount (for example, about 100 g) of agricultural products is put in a plastic bag. At this time, if the size and weight of the crops are a problem, cut them into appropriate sizes before placing them in a plastic bag.
Next, an organic solvent solution (for example, 5% acetonitrile solution) equivalent to the crop is put in the plastic bag.
Next, the mouth of the plastic bag is closed, the plastic bag is shaken strongly for a predetermined time (for example, 30 seconds), and residual agricultural chemicals adhering to the crop are extracted with an organic solvent solution.
Next, the organic solvent solution (organic solvent solution containing residual agricultural chemicals) in the plastic bag is filtered to remove soil and the like. Thereby, a sample (sample liquid) can be produced.
Note that the sample preparation procedure is not limited to the procedure shown here, and can be arbitrarily changed as appropriate. The type of the sample is not limited to the sample for measuring the residual pesticide adhering to the crop. Any sample may be used as long as it contains a detection target substance such as an organophosphorus pesticide or a carbamate pesticide. Can be changed.

Next, the user brings the detection sensor unit into contact with the sample (first contact step).
Specifically, for example, by dropping the prepared sample (sample liquid) into the liquid reservoir forming unit 15 surrounding the detection sensor unit, the detection sensor unit is brought into contact with the sample.

Next, in a state where the reference sensor unit and the detection sensor unit are arranged in the same environment, the user brings the reference sensor unit and the detection sensor unit into contact with the enzyme substrate included in the enzyme layer 14 (second contact step).
Specifically, for example, when the user operates the operation unit 30 to specify a detection target substance (for example, an agrochemical that may remain in a crop) and instruct the start of measurement, the control unit 50 The measurement of the current value by the acquisition unit 20 connected to the reference sensor unit and the measurement of the current value by the acquisition unit 20 connected to the detection sensor unit are started, and the measured current value of the reference sensor unit and the current of the detection sensor unit The change with time is displayed on the display unit 40. Then, the user can confirm from the display unit 40 that the base current value of the reference sensor unit and the base current value of the detection sensor unit are stable at a certain current value or less after a predetermined time has elapsed. By dropping the substrate solution into both the liquid reservoir forming section 15 surrounding the reference sensor section and the liquid reservoir forming section 15 surrounding the detection sensor section, the reference sensor section and the detection sensor section are brought into contact with the substrate.

  Here, in the case where the reference sensor unit and the detection sensor unit are separate, in order to arrange the reference sensor unit and the detection sensor unit in the same environment, an operation for that purpose (for example, the reference sensor unit and the detection sensor unit are arranged) It is necessary to perform operations such as close placement. On the other hand, in the case of this embodiment, the reference sensor unit and the detection sensor unit are arranged on the same substrate, and the reference sensor unit and the detection sensor unit are integrated. Therefore, since the reference sensor unit and the detection sensor unit are arranged in the same environment without performing the work for arranging the reference sensor unit and the detection sensor unit in the same environment, it is easy to use.

Next, while the reference sensor unit and the detection sensor unit are arranged in the same environment, the control unit 50 causes the acquisition unit 20 to output the output value (response current value) of the reference sensor unit and the output value of the detection sensor unit ( Response current value) is acquired (acquisition step).
That is, the acquisition unit 20 functions as an acquisition unit that acquires the output value (response current value) of the reference sensor unit and the output value (response current value) of the detection sensor unit.

Next, the control unit 50 calculates the second response ratio based on the output value (response current value) of the reference sensor unit acquired in the acquisition step and the output value (response current value) of the detection sensor unit (response ratio calculation). Step).
That is, the control unit 50 acquires the output value (response current value) of the reference sensor unit and the output value of the detection sensor unit after the detection sensor unit is brought into contact with the sample (acquired by the acquisition unit (acquisition unit 20)). And a response ratio calculation means for calculating the second response ratio based on the response current value).

Here, the second response ratio is acquired from the second reference side response value acquired from the reference sensor unit after contacting the detection sensor unit with the sample, and from the detection sensor unit after contacting the detection sensor unit with the sample. It is a ratio to the second detection side response value.
Similar to the first reference side response value and the second detection side response value, the second reference side response value and the second detection side response value can be obtained, for example, as shown in FIG.
Specifically, the second reference side response value is such that the output value (response current value) of the reference sensor unit exceeds the first response detection threshold due to contact between the reference sensor unit and the enzyme substrate included in the enzyme layer 14. This is the output value (response current value) of the reference sensor unit after the first standby time has elapsed.
The second detection-side response value is determined after the output value (response current value) of the detection sensor unit exceeds the second response detection threshold due to contact between the detection sensor unit and the enzyme substrate included in the enzyme layer 14. 2 is an output value (response current value) of the detection sensor unit after the standby time has elapsed.

The second reference side response value and the second detection side response value are the same as the first reference side response value and the second detection side response value, for example, as shown in FIG. 5B, for a predetermined period of the response current value. May be an average value.
Specifically, the second reference side response value is such that the output value (response current value) of the reference sensor unit exceeds the first response detection threshold due to contact between the reference sensor unit and the enzyme substrate included in the enzyme layer 14. It may be an average value of a predetermined period of the output value (response current value) of the reference sensor unit after the first standby time has elapsed.
Similarly, the second detection-side response value is obtained after the output value (response current value) of the detection sensor unit exceeds the second response detection threshold due to contact between the detection sensor unit and the enzyme substrate included in the enzyme layer 14. It may be an average value of a predetermined period of the output value (response current value) of the detection sensor unit after the second standby time has elapsed.

Next, the control unit 50 determines the concentration of the detection target substance contained in the sample based on the ratio between the first response ratio stored in the control unit 50 and the second response ratio calculated in the response ratio calculation step. Determination (density determination step).
That is, the control unit 50 includes a first response ratio (= (first detection side response value) / (first reference side response value)) stored in the storage unit (control unit 50) and a response ratio calculation unit ( Based on the ratio of the second response ratio (= (second detection side response value) / (second reference side response value)) calculated by the control unit 50), the concentration of the detection target substance contained in the sample is determined. It functions as a density determination means for determination.
Specifically, the concentration [I] of the detection target substance is
RA (relative activity) = (second response ratio) / (first response ratio)
Inhibition rate = 1-RA = 1 / (1+ (K _i / [I]) × (1+ [S] / K _m ))
Can be determined (calculated).
However, _Ki is the inhibition constant of the detection target substance designated by the user operating the operation unit 30, and [S] is the substrate concentration (even if the user inputs the concentration of the substrate solution to be dropped by operating the operation unit 30). it may, the concentration of the substrate solution is added dropwise may be determined in advance.), K _m is the Michaelis constant.

Next, the control unit 50 displays the density determined in the density determination step on the display unit 40. Further, the control unit 50 determines whether or not the concentration determined in the concentration determination step exceeds a predetermined warning threshold value, and displays a predetermined warning display on the display unit 40 when it exceeds the predetermined warning threshold value.
That is, the display unit 40 and the control unit 50 function as a warning unit that issues a warning when the concentration determined by the concentration determination unit (control unit 50) exceeds a predetermined warning threshold value.

Here, in the present embodiment, the user can operate the operation unit 30 to specify a plurality of substances (for example, a plurality of pesticides that may remain on the crop) as the detection target substances.
That is, the operation unit 30 functions as a designation unit that designates a plurality of substances as detection target substances in response to a user operation.

Then, when a plurality of substances are designated as detection target substances, the control unit 50 assumes that only one of the designated plurality of substances is included in the sample, and the plurality of substances Each density is determined.
Specifically, for example, it is assumed that substance A, substance B, and substance C are designated as detection target substances. In this case, the control unit 50 determines (calculates) the concentration [I _A ] of the substance A assuming that the sample contains only the substance A, and K _i = the inhibition constant of the substance A. Further, assuming that only the substance B is included in the sample, the concentration [I _B ] of the substance B is determined (calculated) with K _i = the inhibition constant of the substance B. Further, assuming that the sample contains only the substance C, the concentration [I _C ] of the substance C is determined (calculated) with K _i = inhibition constant of the substance C.

Thereafter, the control unit 50 displays the determined concentrations (in this example, [I _A ], [I _B ], and [I _C ]) on the display unit 40, and even one of the determined concentrations is displayed. A warning is provided when a predetermined warning threshold is exceeded.
Specifically, for example, in this example,
If [I _A ] ∧ [I _B ] ∧ [I _C ] ≧ warning threshold, a warning display such as “extremely dangerous” is displayed on the display unit 40,
If [I _A ] ∨ [I _B ] ∨ [I _C ] ≧ warning threshold, warning indications such as “danger”, “gray”, “possibility of danger” are displayed on the display unit 40,
If [I _A ] ∧ [I _B ] ∧ [I _C ] <warning threshold, a display such as “safe” is displayed on the display unit 40.

In the present embodiment, the control unit 50 calculates the concentration [I] of the detection target substance by a mathematical formula (inhibition rate = 1−RA = 1 / (1+ (K _i / [I]) × (1+ [S] / K). _m))) has been configured to determine (calculate) using, not limited thereto, for example, the storage area in the control unit 50, showing the relationship between the concentration and the inhibition rate of the substance to be detected It is also possible to store calibration curve data relating to a calibration curve such as a calibration curve (see FIG. 6) and determine the concentration [I] of the detection target substance based on the calibration curve data.
Here, FIG. 6 shows a calibration curve of a substance having an inhibition constant (K _ia ) of 10 ⁻⁶ , a calibration curve of a substance having an inhibition constant (K _ib ) of 10 ⁻⁷ , and an inhibition constant (K _ic ). And a calibration curve of a substance having a value of 10 ⁻⁸ .
According to FIG. 6, since the horizontal axis is the logarithm of concentration [I] (mol / L) and the vertical axis is the inhibition rate (%), if the inhibition rate (= 100 × (1-RA)) is known, from the calibration curve The density [I] can be determined (acquired).

Here, the enzyme sensor is likely to be deteriorated such as a decrease in enzyme activity.
Therefore, in the present embodiment, in order to suppress the influence of variations between sensors due to deterioration or the like, the response current value before and after contact with the detection target substance is measured using the same sensor unit Se.

In addition, although the enzyme sensor is excellent in sensitivity and selectivity, it is easily affected by changes in the external environment such as temperature and pH.
Therefore, conventionally, in order to suppress the influence of changes in the external environment such as temperature and pH, the response current value while keeping the ambient temperature constant using a Peltier element or the like or keeping the pH constant with a buffer solution or the like. Was measuring.
Furthermore, when the response current value before and after contact with the detection target substance is measured using the same sensor unit Se as in this embodiment, the measurement before contact and the measurement after contact are the same. Must be done in an external environment.
However, the response current value is measured while keeping the ambient temperature constant using a Peltier element or the like, or the pH is kept constant with a buffer solution, or the external environment is the same in the measurement before and after contact with the detection target substance. In order to achieve this, there is a problem that an expensive and complicated mechanism or system is necessary, and complicated adjustment for measurement is required.

Therefore, in this embodiment, a reference sensor unit, that is, a sensor unit Se that is not brought into contact with the detection target substance, and a detection sensor unit, that is, a sensor unit Se that is brought into contact with the detection target substance, are prepared, and the response current of the reference sensor unit The value and the response current value of the detection sensor unit are measured in the same environment. The ratio of the response current value of the detection sensor unit to the response current value of the reference sensor unit is calculated as a response ratio, and the concentration of the detection target substance is determined based on the calculated response ratio.
As a result, the effects of changes in the external environment such as temperature and pH can be absorbed, so it is necessary to keep the external environment constant using expensive and complicated mechanisms and systems, and the external environment can be measured before and after contact with the detection target substance. Are not required to be the same, and complicated adjustment for measurement is not required, so that simple measurement is possible.

In addition, conventionally, the response current value of the sensor unit after a predetermined time has elapsed from the time when the sensor unit and the substrate contacted each other is a response value (a value used for detection or quantification of the detection target substance). .
Therefore, in the configuration in which the user drops the substrate solution onto the sensor unit, the control unit of the sensor system cannot determine the timing at which the sensor unit and the substrate are in contact with each other. The substrate solution was dropped on the sensor unit using a syringe, a pump, or the like that can be controlled by the control unit so that the timing of contact can be determined.
However, in order to drop the substrate solution onto the sensor unit using a syringe, a pump, or the like, there is a problem that an expensive and complicated mechanism or system is required, and complicated adjustment for dropping is necessary. .

Therefore, in this embodiment, the response current of the sensor unit Se after a predetermined standby time has elapsed after the response current value of the sensor unit Se exceeds a predetermined response detection threshold due to contact between the sensor unit Se and the substrate. The value is a response value (a value used for detection or quantification of a detection target substance. First reference side response value, first detection side response value, second reference side response value, and second detection side response value). I am going to do that.
Thereby, even if the timing at which the sensor unit Se and the substrate are in contact is unknown, the control unit 50 determines whether or not the response current value of the sensor unit Se exceeds the response detection threshold, and the response current value of the sensor unit Se When the detection threshold is exceeded, it is possible to obtain an accurate response value simply by determining whether or not the standby time has elapsed. Therefore, the sensor unit Se and the substrate can be separated using an expensive and complicated mechanism or system. There is no need to measure the contact timing and no complicated adjustment for dripping is required, so that simple measurement is possible.

  Hereinafter, the invention will be described with reference to specific examples, but the invention is not limited thereto.

First, an enzyme sensor 10 that electrochemically detects an organophosphorus pesticide (specifically, methamidophos) contained in a sample was prepared using cholinesterase as an enzyme.
First, a carbon ink is applied on a glass epoxy substrate (substrate 11) by a screen printing method, and then dried to form a working electrode 121 and a counter electrode 122, and a glass epoxy substrate (substrate 11) by a screen printing method. A reference electrode 123 was formed by applying a silver / silver chloride ink thereon and then drying.

Next, TCNQ (electron carrier) is added to the carbon ink to prepare an electron carrier-containing ink, and the electron carrier-containing ink is applied onto the working electrode 121 by a screen printing method and then dried. The transmitter layer 13 was formed.
Next, the insulating film 16 is formed by applying an insulating ink to the portion of the surface of the substrate 11 on the side where the electrode 12 is formed, excluding the region to be the sensor portion Se, and then drying by applying a screen printing method. did.
Next, an acrylic cylindrical liquid reservoir forming portion 15 was fixed to the edge of the opening (opening for exposing the sensor portion Se) formed in the insulating film 16 on the insulating film 16.

Next, an enzyme solution containing cholinesterase was prepared, and powdered mesoporous silica was added to the enzyme solution to prepare a silica-containing enzyme solution. Then, the silica-containing enzyme solution was stirred with a rotator to prepare an enzyme-silica complex in which the enzyme was fixed inside the pores of mesoporous silica.
Subsequently, the silica-containing enzyme solution containing the enzyme-silica complex was added with a modified poval solution and a binder solution containing adipic acid dihydrazide, which is a crosslinking agent thereof, and stirred to prepare a silica / binder-containing enzyme solution. And the enzyme layer 14 was formed by dripping the said silica-binder containing enzyme solution on the electron carrier layer 13, apply | coating with a spin coater, and making it dry. Thereafter, the surface of the enzyme layer 14 is washed with distilled water to wash away the enzyme adsorbed on the outer surface of the mesoporous silica (that is, the enzyme not fixed inside the pores of the mesoporous silica). It was.

And the sensor system 1 was comprised by attaching the produced enzyme sensor 10 to the support part 1a (size: length 5cm x width 5cm x thickness 1cm).
Next, a 5% acetonitrile solution is dropped by a dropper into both the liquid reservoir forming portion 15 surrounding the reference sensor portion of the enzyme sensor 10 and the liquid reservoir forming portion 15 surrounding the detection sensor portion of the enzyme sensor 10 with a dropper. Then, a voltage of +100 mV was applied to both the reference sensor unit and the detection sensor unit, and the system waited until the response current value of the reference sensor unit and the response current value of the detection sensor unit were stabilized.
Next, after confirming that the response current value is stable, a substrate (acetylthiocholine) is formed in both the liquid reservoir forming portion 15 surrounding the reference sensor portion and the liquid reservoir forming portion 15 surrounding the detection sensor portion. The first reference side response value and the first detection side response value are obtained by dropping one drop of the substrate solution with a dropper, and calculated based on the first reference side response value and the first detection side response value. One response ratio was stored in a storage area in the control unit 50. Here, the first response detection threshold value and the second response detection threshold value are 10 nA, the first standby time and the second standby time are 200 seconds, the average value of the response current values for about 10 seconds is the first reference side response value, It was set as 1 detection side response value.

Next, a sample was prepared.
First, spinach and peppers are prepared as crops, and 3 kinds of pesticide solutions (0.01 ppm methamidophos solution, 1 ppm methamidophos solution, 100 ppm methamidophos solution) are prepared by adding methamidophos to 5% acetonitrile solution. Each sample was sprinkled with spinach and peppers to prepare a simulation sample.
Next, 100 g of spinach with a 0.01 ppm methamidophos solution attached was placed in a plastic bag, and 100 mL of a 5% acetonitrile solution was placed in the plastic bag.
Next, the mouth of the plastic bag was closed, the plastic bag was shaken strongly for 30 seconds, and methamidophos adhering to spinach was extracted with an acetonitrile solution.
Next, the acetonitrile solution (acetonitrile solution containing methamidophos) in the plastic bag was filtered to remove soil and the like, thereby preparing Sample A1.
Similarly, sample A2 was prepared using peppers to which a 0.01 ppm methamidophos solution was attached, sample B1 was prepared using spinach to which 1 ppm of methamidophos solution was attached, and sample B2 was prepared using peppers to which a 1 ppm methamidophos solution was attached. Sample C1 was prepared using spinach to which 100 ppm of methamidophos solution was adhered, and sample C2 was prepared using peppers to which 100 ppm of methamidophos solution was adhered.

Next, the first contact step was performed. Specifically, two drops of a 5% acetonitrile solution are dropped with a dropper into the liquid reservoir forming part 15 surrounding the reference sensor part, and two drops of the sample A1 are dropped with a dropper into the liquid reservoir forming part 15 surrounding the detection sensor part. Then, a voltage of +100 mV was applied to both the reference sensor unit and the detection sensor unit and incubated for 5 minutes.
A second contact step was then performed. Specifically, a substrate solution containing a substrate (acetylthiocholine) in both the liquid reservoir forming portion 15 surrounding the reference sensor portion and the liquid reservoir forming portion 15 surrounding the detection sensor portion is 1 by a dropper. Dropped dropwise.

Next, an acquisition step was performed. Specifically, the second reference side response value was acquired from the reference sensor unit, and the second detection side response value was acquired from the detection sensor unit. Here, the average value of the response current values for about 10 seconds was used as the second reference side response value and the second detection side response value.
Next, a response ratio calculation step was performed. Specifically, the second response ratio was calculated based on the acquired second reference side response value and second detection side response value.
Next, a concentration determination step was performed. Specifically, the concentration of methamidophos contained in the sample A1 was determined based on the ratio between the stored first response ratio and the calculated second response ratio.

Similarly, the concentration of methamidophos contained in sample A2, the concentration of methamidophos contained in sample B1, the concentration of methamidophos contained in sample B2, the concentration of methamidophos contained in sample C1, and the concentration of methamidophos contained in sample C2, respectively. Judged. The result is shown in FIG.
As a comparative example, the concentration of methamidophos contained in Sample A1, Sample A2, Sample B1, Sample B2, Sample C1, and Sample C2 was determined using gas chromatography / mass spectrometry (GC / MS). The result is also shown in FIG.

As shown in FIG. 7, the sensor system 1 of the present embodiment can measure the concentration of agricultural chemicals as quickly and highly sensitively as GC / MS, even though the pretreatment is easier than GC / MS. I understood that.
In addition, in the case of agricultural products, the pesticide used in many cases is known in advance, and even when there are a plurality of used pesticides, it is considered to be extremely effective to use the sensor system 1 for primary screening of residual pesticides.

  According to the sensor system 1 of the present embodiment described above, the sensor system 1 includes the enzyme sensor 10 that detects a detection target substance contained in a predetermined sample using a substance that inhibits enzyme activity as a detection target substance. The enzyme sensor 10 includes a plurality of sensor units Se having the same configuration, a part of the plurality of sensor units Se is a reference sensor unit that does not contact the sample, and the rest is a detection sensor unit that contacts the sample. A storage unit (control unit 50) for storing a first response ratio calculated based on the output value of the reference sensor unit and the output value of the detection sensor unit before the detection sensor unit is brought into contact with the sample; An acquisition unit (acquisition unit 20) for acquiring the output value of the sensor unit and the output value of the detection sensor unit, and the detection sensor unit acquired by the acquisition unit after contacting the sample Based on the output value of the quasi-sensor unit and the output value of the detection sensor unit, response ratio calculation means (control unit 50) for calculating the second response ratio, the first response ratio stored in the storage means, Concentration determining means (control unit 50) for determining the concentration of the detection target substance contained in the sample based on the ratio of the second response ratio calculated by the response ratio calculating means, and the first response ratio is A first reference side response value acquired from the reference sensor unit before contacting the detection sensor unit with the sample, a first detection side response value acquired from the detection sensor unit before contacting the detection sensor unit with the sample, The first reference side response value is the value after the predetermined first waiting time has elapsed since the output value of the reference sensor unit exceeded the predetermined first response detection threshold value due to contact with the enzyme substrate. Output value of the reference sensor unit The value is an output value of the detection sensor unit after a predetermined second waiting time has elapsed since the output value of the detection sensor unit exceeded a predetermined second response detection threshold value due to contact with the enzyme substrate. The two response ratios are the second reference side response value acquired from the reference sensor unit after contacting the detection sensor unit with the sample and the second detection acquired from the detection sensor unit after contacting the detection sensor unit with the sample. The second reference side response value is obtained after the first waiting time has elapsed since the output value of the reference sensor unit exceeded the first response detection threshold value due to contact with the enzyme substrate. It is the output value of the reference sensor unit, and the second detection-side response value is obtained after the second waiting time has elapsed after the output value of the detection sensor unit exceeds the second response detection threshold due to contact with the enzyme substrate. The output value of the detection sensor The

By configuring in this way, it is possible to absorb the influence of changes in the external environment such as temperature and pH, so there is no need to keep the external environment constant by using an expensive and complicated mechanism or system. Since no complicated adjustment is required, simple measurement is possible.
Further, even when the timing at which the sensor unit Se and the substrate are in contact is unknown, the control unit 50 determines whether or not the output value of the sensor unit Se exceeds the response detection threshold, and the output value of the sensor unit Se sets the response detection threshold. When it exceeds, it is possible to obtain an accurate response value simply by determining whether or not the waiting time has elapsed, so the timing at which the sensor unit Se and the substrate contact each other using an expensive and complicated mechanism or system In addition, since it is not necessary to make a complicated adjustment for dripping, etc., simple measurement is possible.
Therefore, high-speed and high-sensitivity measurement can be performed with a simple configuration. That is, reliable measurement can be performed at low cost. As a result, it is possible to provide a sensing system that is capable of screening pesticide residues with high speed and high sensitivity while being a simple method.

Moreover, according to the sensor system 1 of this embodiment demonstrated above, the output value of a reference | standard sensor part is made into a 1st response detection threshold value by contact with the substrate of an enzyme, with a 1st reference | standard side response value and a 2nd reference | standard side response value. And the first detection side response value and the second detection side response value are determined by contact with the enzyme substrate. It is also possible to use an average value of a predetermined period of the output value of the detection sensor unit after the second standby time has elapsed after the output value of the detection sensor unit exceeds the second response detection threshold.
Therefore, it is possible to obtain more accurate values as response values (first reference side response value, second reference side response value, first detection side response value, second detection side response value).

Further, according to the sensor system 1 of the present embodiment described above, warning means (display unit 40 and control) that issues a warning when the concentration determined by the concentration determination means (control unit 50) exceeds a predetermined warning threshold value. Part 50).
Therefore, the user can be surely recognized that the concentration of the detection target substance contained in the predetermined sample is high.
In the present embodiment, the predetermined warning display is displayed on the display unit 40 when the determined concentration exceeds the warning threshold. However, the present invention is not limited to this. For example, the sensor system 1 It is also possible to provide a speaker and to output a predetermined warning sound from the speaker when the determined density exceeds the warning threshold value. In this case, the speaker and control unit 50 functions as a warning unit.

In addition, according to the sensor system 1 of the present embodiment described above, a specification unit (operation unit 30) that specifies a plurality of substances as detection target substances according to a user operation is provided, and a concentration determination unit (control unit 50). Assumes that only one of the plurality of substances designated by the designation means is included in the sample, determines the concentration of each of the plurality of substances, and warning means (display unit 40 and control unit 50) Is configured to issue a warning when one of the densities determined by the density determination means exceeds the warning threshold.
In other words, if there are multiple substances that can be detected, each concentration is determined, and if any one of the determined concentrations exceeds the warning threshold, a warning is given. The form of the sensor system 1 can be effectively used for primary screening of residual agricultural chemicals and the like.

Moreover, according to the sensor system 1 of this embodiment demonstrated above, it has the support part 1a which supports the enzyme sensor 10 so that attachment or detachment is possible, and the enzyme sensor 10 is a disposable sensor.
Therefore, since the new measurement can be performed only by replacing the enzyme sensor 10, further cost reduction can be achieved.

Further, according to the sensor system 1 of the present embodiment described above, the sample is a liquid, and the enzyme sensor 10 has a liquid reservoir around each of the plurality of sensors Se.
Therefore, if a sample (sample body) is dropped on the liquid reservoir around the sensor unit Se, the detection target substance contained in the sample can be detected or quantified. Therefore, even with a small amount of sample, high-speed and highly sensitive measurement can be performed. It becomes possible.
The object to be measured may be a solid, but it is washed or diluted with a solvent to obtain a measurement sample.

  According to the detection target substance measurement method of the present embodiment described above, the sensor system 1 of the present embodiment is used to set the concentration of the detection target substance contained in a predetermined sample as the detection target substance. A first detection step in which the detection sensor unit is brought into contact with the sample, and then the reference sensor unit and the detection sensor unit are arranged in the same environment. The second contact step of bringing the detection sensor unit into contact with the enzyme substrate, and then the output value of the reference sensor unit and the detection by the acquisition means while the reference sensor unit and the detection sensor unit are arranged in the same environment The acquisition step of acquiring the output value of the sensor unit, and then the output value of the reference sensor unit acquired in the acquisition step and the detection sensor unit by the response ratio calculation means A response ratio calculating step of calculating a second response ratio based on the force value; then, a first response ratio stored in the storage means by the concentration determination means; and a second response ratio calculated in the response ratio calculation step And a concentration determination step for determining the concentration of the detection target substance contained in the sample based on the ratio.

By configuring in this way, it is possible to absorb the influence of changes in the external environment such as temperature and pH, so there is no need to keep the external environment constant by using an expensive and complicated mechanism or system. Since no complicated adjustment is required, simple measurement is possible.
Further, even when the timing at which the sensor unit Se and the substrate are in contact is unknown, the control unit 50 determines whether or not the output value of the sensor unit Se exceeds the response detection threshold, and the output value of the sensor unit Se sets the response detection threshold. When it exceeds, it is possible to obtain an accurate response value simply by determining whether or not the waiting time has elapsed, so the timing at which the sensor unit Se and the substrate contact each other using an expensive and complicated mechanism or system In addition, since it is not necessary to make a complicated adjustment for dripping, etc., simple measurement is possible.
Therefore, high-speed and high-sensitivity measurement can be performed with a simple configuration. That is, reliable measurement can be performed at low cost.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The substance to be detected is not limited to an agrochemical such as an organophosphorus pesticide or a carbamate pesticide, and can be arbitrarily changed as long as it is a substance that inhibits the activity of the enzyme. In addition, the enzyme can also be arbitrarily changed according to the substance to be detected. Further, the substrate and the like can be arbitrarily changed as appropriate in accordance with the detection target substance and the enzyme.
In the enzyme sensor 10, the reference sensor unit and the detection sensor unit may not be configured integrally, and may be configured separately.

DESCRIPTION OF SYMBOLS 1 Sensor system 1a Support part 10 Enzyme sensor 20 Acquisition part (acquisition means)
40 Display (Warning means)
50 control unit (storage means, response ratio calculation means, concentration determination means, warning means)
Se sensor

Claims (7)

In a sensor system including an enzyme sensor that detects a detection target substance contained in a predetermined sample, using a substance that inhibits the activity of the enzyme as a detection target substance.
The enzyme sensor includes a plurality of sensor units having the same configuration, and a part of the plurality of sensor units is a reference sensor unit that does not contact the sample, and the rest is a detection sensor unit that contacts the sample. ,
Storage means for storing a first response ratio calculated based on an output value of the reference sensor unit and an output value of the detection sensor unit before the detection sensor unit is brought into contact with the sample;
Obtaining means for obtaining an output value of the reference sensor unit and an output value of the detection sensor unit;
Response ratio for calculating a second response ratio based on the output value of the reference sensor unit and the output value of the detection sensor unit obtained after the detection sensor unit is brought into contact with the sample, acquired by the acquisition unit A calculation means;
Concentration determination for determining the concentration of the detection target substance contained in the sample based on the ratio between the first response ratio stored in the storage means and the second response ratio calculated by the response ratio calculation means Means, and
The first response ratio includes a first reference-side response value acquired from the reference sensor unit before the detection sensor unit is brought into contact with the sample, and the detection sensor unit before the detection sensor unit is brought into contact with the sample. And the first detection side response value acquired from
The first reference side response value is the reference sensor after a predetermined first waiting time has elapsed after the output value of the reference sensor unit exceeds a predetermined first response detection threshold value due to contact with the enzyme substrate. Output value,
The first detection-side response value is the detection sensor after a predetermined second waiting time has elapsed after the output value of the detection sensor unit exceeds a predetermined second response detection threshold value due to contact with the enzyme substrate. Output value,
The second response ratio includes the second reference-side response value acquired from the reference sensor unit after the detection sensor unit is brought into contact with the sample, and the detection sensor unit after the detection sensor unit is brought into contact with the sample. And the second detection side response value acquired from
The second reference side response value is a value of the reference sensor unit after the first waiting time has elapsed after the output value of the reference sensor unit exceeds the first response detection threshold value due to contact with the enzyme substrate. Output value,
The second detection-side response value of the detection sensor unit after the second waiting time has elapsed after the output value of the detection sensor unit exceeds the second response detection threshold value due to contact with the enzyme substrate. A sensor system characterized by an output value. The first reference side response value and the second reference side response value are determined by the first waiting time after the output value of the reference sensor unit exceeds the first response detection threshold due to contact with the enzyme substrate. Is the average value of the output value of the reference sensor unit after a predetermined period of time,
The first detection side response value and the second detection side response value are determined as follows: the second waiting time has elapsed after the output value of the detection sensor unit exceeds the second response detection threshold value due to contact with the enzyme substrate. The sensor system according to claim 1, wherein the sensor system is an average value of output values of the detection sensor unit after a predetermined period.   The sensor system according to claim 1, further comprising a warning unit that issues a warning when the concentration determined by the concentration determination unit exceeds a predetermined warning threshold value. In accordance with a user operation, comprising a designation means for designating a plurality of substances as the detection target substance,
The concentration determining means determines the concentration of each of the plurality of substances, assuming that only one of the plurality of substances specified by the specifying means is included in the sample,
The sensor system according to claim 3, wherein the warning unit issues a warning when any one of the concentrations determined by the concentration determination unit exceeds the warning threshold. A support unit for detachably supporting the enzyme sensor;
The sensor system according to any one of claims 1 to 4, wherein the enzyme sensor is a disposable sensor. The sample is a liquid;
The sensor system according to claim 1, wherein the enzyme sensor has a liquid reservoir around each of the plurality of sensors. 7. A method for measuring a substance to be detected, wherein a substance that inhibits the activity of an enzyme is used as a substance to be detected, and the concentration of the substance to be detected contained in a predetermined sample is measured using the sensor system according to any one of claims 1 to 6. In
A first contact step for bringing the detection sensor unit into contact with the sample;
Next, in a state where the reference sensor unit and the detection sensor unit are arranged in the same environment, a second contact step of bringing the reference sensor unit and the detection sensor unit into contact with the enzyme substrate;
Then, the acquisition step of acquiring the output value of the reference sensor unit and the output value of the detection sensor unit by the acquisition unit while the reference sensor unit and the detection sensor unit are arranged in the same environment,
Next, a response ratio calculation step of calculating the second response ratio based on the output value of the reference sensor unit and the output value of the detection sensor unit acquired in the acquisition step by the response ratio calculation unit;
Next, based on the ratio between the first response ratio stored in the storage unit and the second response ratio calculated in the response ratio calculation step, the concentration determination unit determines the detection target substance contained in the sample. And a concentration determination step for determining the concentration.

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