Organic Field-Effect Transistor Gas Sensor, Odor Measurement Circuit and Method

Abstract

The present invention belongs to the technical field of food biogenic amine detection, and discloses an organic field effect transistor gas sensor, an odor measurement circuit and a method. According to the present invention, the organic field effect transistor and the odor detection circuit sense food biogenic amine, causing changes in the internal characteristics of the organic field effect transistor, which in turn leads to changes in the circuit voltage signal. The voltage gain of the feedback circuit is adjusted according to the voltage signal displayed on the oscilloscope, so that the voltage displayed on the oscilloscope is equal to the source voltage, realizing the adjustment of the voltage gain by the mobile terminal. Based on the relationship between the source voltage and the voltage gain, the changes in the charge carrier mobility and the threshold voltage are determined. Thus, the detection result of food biogenic amine is obtained according to the changes in the charge carrier mobility or the threshold voltage, achieving the purpose of rapid on-site detection.

Description

Technical Field

[0001] The present invention relates to the technical field of food biogenic amine detection, and particularly to an organic field effect transistor gas sensor, an odor measurement circuit and a method. Background Art

[0002] Biogenic amines are a class of nitrogen-containing low molecular organic bases, mainly formed by the decarboxylation of amino acids, and widely exist in meat products, aquatic products and fermented products rich in amino acids and proteins. When the intake of biogenic amines is excessive, it will cause adverse reactions to the human body.

[0003] Current biogenic amine detection methods include conventional physical and chemical analysis methods, electronic nose recognition methods based on gas sensor arrays and pattern recognition, and traditional organic field effect transistor gas sensors. Traditional organic field effect transistor gas sensors can solve the disadvantages of conventional physical and chemical analysis methods and electronic nose recognition methods based on gas sensor arrays and pattern recognition, such as the need for sample pretreatment before detection, high working temperature, and poor selectivity. However, there is still a problem that it is necessary to use a semiconductor parameter analyzer or similar instrument for measurement in the laboratory, and rapid measurement cannot be carried out at the sensing site of the odor sensor.

[0004] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main object of the present invention is to provide an organic field effect transistor gas sensor, an odor measurement circuit and a method, aiming to solve the technical problem that rapid measurement cannot be carried out at the sensing site of the odor sensor in the prior art.

[0006] To achieve the above object, the present invention provides an organic field effect transistor gas sensor, which includes: a substrate, a source electrode and a drain electrode are arranged above the substrate, an organic semiconductor layer is arranged above the source electrode and the drain electrode, a biogenic amine sensitive layer is arranged above the organic semiconductor layer, a water droplet is arranged above the biogenic amine sensitive layer, and a gate electrode is arranged above the water droplet.

[0007] In addition, to achieve the above object, the present invention also provides an odor measurement circuit, which includes: a voltage input circuit, a coupling circuit, the organic field effect transistor odor sensor as described above, a voltage dividing circuit, a feedback circuit and a display circuit connected in sequence, and the feedback circuit is also connected to a mobile terminal;

[0008] The coupling circuit is used to couple the input voltage of the voltage input circuit with the organic field effect transistor odor sensor, so that the source voltage of the organic field effect transistor odor sensor is equal to the input voltage;

[0009] The voltage dividing circuit is used to make the source voltage of the organic field effect transistor odor sensor equal to the source-drain voltage;

[0010] The display circuit is used to display the drain voltage of the organic field effect transistor odor sensor;

[0011] The feedback circuit is used to amplify the drain voltage and adjust the resistance through the mobile terminal until the amplified drain voltage is equal to the source voltage.

[0012] Optionally, the coupling circuit includes a first operational amplifier;

[0013] The output end of the voltage input circuit is connected to the non-inverting input end of the first operational amplifier, the inverting input end of the first operational amplifier is connected to the output end of the first operational amplifier, and the output end of the first operational amplifier is connected to the source of the organic field effect transistor odor sensor.

[0014] Optionally, the feedback circuit includes a second operational amplifier, a fixed resistor, and a variable resistor;

[0015] The non-inverting input end of the second operational amplifier is connected to the drain of the organic field effect transistor odor sensor, the output end of the second operational amplifier is connected to the first end of the fixed resistor, the second end of the fixed resistor is connected to the inverting input end of the second operational amplifier, the output end of the second operational amplifier is connected to the first end of the display circuit, the second end of the display circuit is grounded, the second end of the fixed resistor is connected to the first end of the variable resistor, the adjustable end of the variable resistor is connected to the mobile terminal, the second end of the variable resistor is grounded, and the gate of the organic field effect transistor odor sensor is grounded.

[0016] To achieve the above object, the present invention also provides an odor measurement method. The odor measurement method is applied to the odor measurement circuit as shown above. The odor measurement circuit includes: a voltage input circuit, a coupling circuit, an organic field effect transistor odor sensor, a voltage dividing circuit, a feedback circuit, and a display circuit connected in sequence. The feedback circuit is also connected to a mobile terminal. The method includes the following steps:

[0017] The coupling circuit couples the input voltage of the voltage input circuit with the organic field effect transistor odor sensor to make the source voltage of the organic field effect transistor odor sensor equal to the input voltage;

[0018] The voltage dividing circuit makes the source voltage of the organic field effect transistor odor sensor equal to the source-drain voltage;

[0019] The display circuit displays the drain voltage of the organic field effect transistor odor sensor;

[0020] The feedback circuit amplifies the drain voltage and performs resistance adjustment through the mobile terminal until the amplified drain voltage is equal to the source voltage;

[0021] Determine the voltage gain according to the source voltage and the drain voltage;

[0022] Determine the charge carrier mobility and the threshold voltage according to the source voltage and the voltage gain;

[0023] Adjust the source voltage multiple times to obtain the change in the charge carrier mobility and the change in the threshold voltage;

[0024] Obtain the bioamine odor measurement result according to the change in the charge carrier mobility or the change in the threshold voltage.

[0025] Optionally, the determining the charge carrier mobility and the threshold voltage according to the source voltage and the voltage gain includes:

[0026] Obtain the first correspondence with the saturation current according to the source voltage and the voltage gain;

[0027] Obtain the second correspondence with the saturation current according to the charge carrier mobility, the threshold voltage and the source voltage;

[0028] Obtain the correspondence between the source voltage and the voltage gain of the organic field effect crystal odor sensor according to the first correspondence and the second correspondence;

[0029] Obtain the charge carrier mobility and the threshold voltage according to the correspondence between the source voltage and the voltage gain of the organic field effect crystal odor sensor.

[0030] Optionally, the obtaining the charge carrier mobility and the threshold voltage according to the correspondence between the source voltage and the voltage gain of the organic field effect crystal odor sensor includes:

[0031] Obtain a relationship curve graph according to the correspondence between the source voltage and the voltage gain of the organic field effect crystal odor sensor;

[0032] Obtain the threshold voltage according to the intercept of the curve in the relationship curve graph;

[0033] Obtain the charge carrier mobility according to the slope of the relationship curve graph.

[0034] Optionally, the obtaining the saturation current according to the source voltage and the voltage gain includes:

[0035] Determine the corresponding relationship between the saturation current, the first resistor, and the drain voltage according to the corresponding relationship between the source voltage, the voltage gain, and the drain voltage;

[0036] Obtain the saturation current based on the drain voltage and the first resistor.

[0037] Optionally, the determining the voltage gain according to the source voltage and the drain voltage includes:

[0038] Determine the difference between the source voltage and the drain voltage according to the source voltage and the drain voltage;

[0039] Obtain the resistance adjustment instruction sent by the mobile terminal according to the difference;

[0040] Adjust the adjustable resistor to the target resistance value according to the resistance adjustment instruction;

[0041] Determine the voltage gain according to the target resistance value and the fixed resistor resistance value.

[0042] Optionally, the obtaining the change in the charge carrier mobility and the change in the threshold voltage by adjusting the source voltage multiple times includes:

[0043] Adjust the source voltage multiple times to obtain multiple relationship curve graphs;

[0044] Obtain multiple charge carrier mobilities and multiple threshold voltages according to the multiple relationship curve graphs;

[0045] Obtain the change in the charge carrier mobility and the change in the threshold voltage according to the multiple charge carrier mobilities and the multiple threshold voltages.

[0046] In the present invention, a food biogenic amine is sensed through an organic field-effect transistor and an odor detection circuit, which causes a change in the internal characteristics of the organic field-effect transistor, thereby resulting in a change in the circuit voltage signal. The voltage gain of the feedback circuit is adjusted according to the voltage signal displayed on the oscilloscope, so that the voltage displayed on the oscilloscope is equal to the source voltage, realizing the adjustment of the voltage gain by the mobile terminal, and determining the change in the charge carrier mobility and the threshold voltage according to the relationship between the source voltage and the voltage gain. Therefore, the detection result of the food biogenic amine is obtained according to the change in the charge carrier mobility or the threshold voltage, achieving the purpose of rapid detection on-site. Description of the Drawings

[0047] Figure 1 It is a schematic structural diagram of an embodiment of the organic field-effect transistor gas sensor of the present invention;

[0048] Figure 2 Schematic diagram of a circuit of an embodiment of an odor measurement circuit according to the present invention;

[0049] Figure 3 Schematic diagram of a circuit of another embodiment of an odor measurement circuit according to the present invention;

[0050] Figure 4 Schematic flowchart of a process of an embodiment of an odor measurement method according to the present invention;

[0051] Figure 5 Schematic curve diagram of an embodiment of an odor measurement method according to the present invention.

[0052] The realization, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0053] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0054] The embodiment of the present invention provides an organic field effect transistor gas sensor. Refer to Figure 1 , Figure 1 Schematic diagram of the structure of an organic field effect transistor gas sensor according to the present invention.

[0055] In this embodiment, the organic field effect transistor gas sensor includes:

[0056] A substrate, a source electrode and a drain electrode are arranged above the substrate, an organic semiconductor layer is arranged above the source electrode and the drain electrode, a biogenic amine sensitive layer is arranged above the organic semiconductor layer, a water droplet is arranged above the biogenic amine sensitive layer, and a gate electrode is arranged above the water droplet. By arranging the biogenic amine sensitive layer in this embodiment, the detection ability of the organic field effect transistor gas sensor for food biogenic amines can be improved.

[0057] Refer to Figure 2 Figure 3 , Figure 2 Figure 3 Schematic diagram of a circuit of an embodiment of an odor measurement circuit according to the present invention.

[0058] Based on the above first embodiment, the odor measurement circuit of this embodiment includes:

[0059] A voltage input circuit 10, a coupling circuit 20, an organic field effect transistor odor sensor 30, a voltage dividing circuit 40, a feedback circuit 50 and a display circuit 60 which are connected in sequence, and the feedback circuit 50 is also connected to a mobile terminal.

[0060] The coupling circuit 20 includes a first operational amplifier, the feedback circuit 50 includes a second operational amplifier, a fixed resistor, and the adjustable resistor display circuit 60 includes an oscilloscope.

[0061] Voltage input circuit 10: It is used to input the voltage generated by the signal generator into the first operational amplifier to generate an amplified voltage.

[0062] It should be noted that the signal generator is a device that provides a driving voltage for the organic field effect transistor odor sensor. The voltage V output by the signal generator i is a square wave voltage that varies back and forth within a certain voltage range. In order to reduce the bias pressure on the gate, the preferred voltage range is +3V to -3V.

[0063] Coupling circuit 20: It is used to couple the input voltage of the voltage input circuit with the organic field effect transistor odor sensor, so that the source voltage of the organic field effect transistor odor sensor is equal to the input voltage.

[0064] The output terminal of the signal generator is connected to the non-inverting input terminal of the first operational amplifier. The inverting input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier. The output terminal of the first operational amplifier is connected to the source of the organic field effect transistor odor sensor.

[0065] It should be noted that the connection of the inverting input terminal of the first operational amplifier to the output terminal of the first operational amplifier is for connection in the negative feedback mode. In this case, it can ensure the stability of the voltage while amplifying the voltage.

[0066] Organic field effect transistor odor sensor 30: The organic field effect transistor odor sensor 30 is used to sense biogenic amines in the external environment. By capturing external biogenic amines, it is converted into a characteristic change inside the organic field effect transistor odor sensor 30.

[0067] Voltage dividing circuit 40: It is used to make the source voltage of the organic field effect transistor odor sensor equal to the source-drain voltage.

[0068] It should be noted that a first resistor is set in the voltage dividing circuit 30. One end of the first resistor is connected in series with the drain of the organic field effect transistor odor sensor, and the other end is grounded.

[0069] It should be understood that the first resistor refers to a fixed-value resistor, which is connected to the organic field effect transistor odor sensor and plays a voltage dividing role. The resistance value of the first resistor is three orders of magnitude smaller than the channel conduction resistance value of the organic field effect transistor.

[0070] In a specific implementation, since one end of the first resistor is grounded and the other end is directly connected to the organic field-effect transistor odor sensor, when the resistance value of the first resistor is much smaller than the channel conduction resistance of the organic field-effect transistor, the source-drain voltage V of the organic field-effect transistor SD is almost equal to the source voltage V S .

[0071] Feedback circuit 50: It is used to amplify the drain voltage and adjust the resistance through the mobile terminal until the amplified drain voltage is equal to the source voltage.

[0072] The non-inverting input terminal of the second operational amplifier is connected to the drain of the organic field-effect transistor odor sensor. The output terminal of the second operational amplifier is connected to the first end of the fixed resistor. The second end of the fixed resistor is connected to the inverting input terminal of the second operational amplifier. The output terminal of the second operational amplifier is connected to the first end of the oscilloscope. The second end of the oscilloscope is grounded. The second end of the fixed resistor is connected to the first end of the adjustable resistor. The adjustable end of the adjustable resistor is connected to the mobile terminal. The second end of the adjustable resistor is grounded. The gate of the organic field-effect transistor odor sensor is grounded.

[0073] Display circuit 60: It is used to display the drain voltage of the organic field-effect transistor odor sensor.

[0074] It should be noted that in the display circuit 60, the oscilloscope is used to display the drain voltage V D , one end of the oscilloscope is connected to the output terminal of the second operational amplifier and the other end is grounded.

[0075] In this embodiment, by coupling the voltage output by the signal generator with the organic field-effect transistor, the voltage of the signal generator is made equal to the source voltage of the organic field-effect transistor. According to the square-wave voltage output by the signal generator, the source of the organic field-effect transistor is driven. When the organic field-effect transistor senses external biogenic amines, the characteristics inside the organic field-effect transistor will change. The drain of the organic field-effect transistor is connected in series with a resistor for voltage division, and this resistor is grounded, making the source-drain voltage of the organic field-effect transistor equal to the source voltage. This can facilitate obtaining the source-drain voltage of the organic field-effect transistor, outputting the drain voltage to the oscilloscope, enabling the oscilloscope to display the drain voltage, and amplifying the drain voltage of the organic field-effect transistor through the second operational amplifier. Thus, the characteristic change inside the organic field-effect transistor is converted into a voltage gain of the drain voltage, turning an unmeasurable quantity into an acquirable quantity and improving the measurement efficiency.

[0076] The embodiment of the present invention provides an odor measurement method. Refer to Figure 4 ,Figure 4 Schematic diagram of a process of an odor measurement method according to an embodiment of the present invention.

[0077] In this embodiment, the odor measurement method is applied to the odor measurement circuit described in the above embodiment. The odor measurement circuit includes: a voltage input circuit, a coupling circuit, an organic field effect transistor odor sensor, a voltage dividing circuit, a feedback circuit, and a display circuit connected in sequence. The feedback circuit is also connected to a mobile terminal and includes the following steps:

[0078] Step S10: The coupling circuit couples the input voltage of the voltage input circuit with the organic field effect transistor odor sensor, so that the source voltage of the organic field effect transistor odor sensor is equal to the input voltage.

[0079] It should be noted that the coupling circuit includes a first operational amplifier. The output end of a signal generator is connected to the non-inverting input end of the first operational amplifier. The inverting input end of the first operational amplifier is connected to the output end of the first operational amplifier. The output end of the first operational amplifier is connected to the source of the organic field effect transistor odor sensor.

[0080] It can be understood that the signal generator V i is coupled with the organic field effect transistor through a voltage follower composed of the first operational amplifier, so that the source voltage V S = V i . The voltage follower is formed by the negative feedback connection mode of the first operational amplifier.

[0081] Step S20: The voltage dividing circuit makes the source voltage of the organic field effect transistor odor sensor equal to the source-drain voltage.

[0082] It should be noted that a first resistor is provided in the voltage dividing circuit 30. One end of the first resistor is connected in series with the drain of the organic field effect transistor odor sensor, and the other end is grounded.

[0083] It should be understood that the first resistor refers to a fixed-value resistor, which is connected to the organic field effect transistor odor sensor and plays a role in voltage division. The resistance value of the first resistor is three orders of magnitude smaller than the channel on-resistance value of the organic field effect transistor.

[0084] In a specific implementation, because one end of the first resistor is grounded and the other end is directly connected to the organic field effect transistor odor sensor, when the first resistor is much smaller than the channel on-resistance value of the organic field effect transistor, the source-drain voltage V SD of the organic field effect transistor is almost equal to the source voltage V S .

[0085] Step S30: The display circuit displays the drain voltage of the organic field-effect transistor gas sensor.

[0086] It should be noted that one end of the display circuit is connected to the second operational amplifier, and the other end is grounded. The function of the second operational amplifier is to adjust the magnitude of the drain voltage.

[0087] Step S40: The feedback circuit amplifies the drain voltage and adjusts the resistance through the mobile terminal until the amplified drain voltage is equal to the source voltage.

[0088] It should be noted that the feedback circuit amplifies the drain voltage by adjusting the resistance value in the feedback circuit, thereby adjusting the amplification factor of the drain voltage.

[0089] Step S50: Determine the voltage gain according to the source voltage and the drain voltage.

[0090] It should be noted that the voltage gain refers to the multiple by which the drain voltage needs to be amplified. Multiplying this amplification multiple by the current drain voltage can make the multiplication result equal to the source voltage.

[0091] It can be understood that since the source is at a position with a high electric potential and the drain is at a position with a low electric potential, the electric potential of the source is greater than or equal to the electric potential of the drain, and the source voltage is greater than or equal to the drain voltage. Therefore, the voltage gain is greater than or equal to 1.

[0092] In specific implementation, it is necessary to obtain the drain voltage displayed by the oscilloscope, compare the drain voltage with the source voltage, so as to determine the amplification ratio required to amplify the drain voltage to be equal to the source voltage.

[0093] Step S60: Determine the charge carrier mobility and the threshold voltage according to the source voltage and the voltage gain.

[0094] It should be noted that when using the organic field-effect transistor gas sensor to detect different food biogenic amine gases, the charge carrier mobility μ and the threshold voltage V of the organic field-effect transistor T will both change. The charge carrier mobility μ and the threshold voltage V of the organic field-effect transistor T both changing also indicates a change in the characteristics within the organic field-effect transistor.

[0095] In a specific implementation, when an organic field-effect transistor goes from an environment without biogenic amines to an environment with biogenic amines, it will cause changes in the charge carrier mobility and threshold voltage of the organic field-effect transistor, and such changes will further lead to changes in the voltage gain. Therefore, the charge carrier mobility μ and threshold voltage V of the organic field-effect transistor can be further deduced from the relationship between the source voltage and the voltage gain. T 。

[0096] Step S70: Adjust the source voltage multiple times to obtain the changes in the charge carrier mobility and the changes in the threshold voltage.

[0097] In a specific implementation, by adjusting the source voltage multiple times, several sets of corresponding relationships between the source voltage and the voltage gain can be obtained, and several sets of charge carrier mobilities and the threshold voltages can also be obtained. When the external biogenic amine environment changes, the changes in the charge carrier mobility and the threshold voltage can be obtained.

[0098] Step S80: Obtain the biogenic amine odor measurement result based on the change in the charge carrier mobility or the change in the threshold voltage.

[0099] It should be noted that different biogenic amine gases have corresponding charge carrier mobilities or threshold voltages. Therefore, the corresponding biogenic amine gases can be deduced from the changes in the charge carrier mobility and the threshold voltage.

[0100] In a specific implementation, the current charge carrier mobility and threshold voltage can be continuously determined through the corresponding relationship between the source voltage and the voltage gain. When the organic field-effect transistor gas sensor detects the presence of biogenic amines in the external environment, intuitively, the relationship between the source voltage and the voltage gain will change. The change in the relationship between the source voltage and the voltage gain can reflect the change in the charge carrier mobility or the threshold voltage, and the biogenic amines can be determined by the change in the charge carrier mobility or the threshold voltage. In the actual detection process, since the changes in the charge carrier mobility and the threshold voltage occur in pairs, the change in the single charge carrier mobility can be used as the detection index, or the change in the single threshold voltage can be used as the detection index. Of course, the charge carrier mobility and the threshold voltage can also be used together as the index for detecting biogenic amines. This embodiment does not limit this.

[0101] In order to further determine the charge carrier mobility and the threshold voltage, step S70 further includes:

[0102] Obtain the first corresponding relationship with the saturation current according to the source voltage and the voltage gain.

[0103] It should be noted that when a voltage is applied to the source electrode, since the gate of the organic field-effect transistor is grounded, the organic field-effect transistor will conduct and enter the saturation state. At this time, the current in the organic field-effect transistor is the saturation current.

[0104] It should be noted that the first correspondence of the saturation current refers to the correspondence among the source voltage, the voltage gain, and the saturation current. The formula 1 for determining the saturation current according to the source voltage and the voltage gain is as follows:

[0105]

[0106] Wherein, I D,sat represents the saturation current, V S represents the source voltage, G represents the voltage gain, and R1 represents the first resistor.

[0107] According to the charge carrier mobility, the threshold voltage, and the source voltage, a second correspondence with the saturation current is obtained.

[0108] It should be noted that the second correspondence of the saturation current refers to the correspondence among the charge carrier mobility, the threshold voltage, and the source voltage and the saturation current. The formula 2 for determining the saturation current according to the charge carrier mobility, the threshold voltage, and the source voltage is as follows:

[0109]

[0110] Wherein, I D,sat represents the saturation current, V SG represents the source-gate voltage, V T represents the threshold voltage, W represents the width of the organic field-effect transistor, L represents the channel length of the organic field-effect transistor, and C i represents the gate oxide capacitance per unit area and represents the charge carrier mobility.

[0111] According to the first correspondence and the second correspondence, the correspondence between the source voltage and the voltage gain of the organic field-effect crystal odor sensor is obtained.

[0112] It should be noted that according to Figure 3 the circuit schematic diagram shown, since the gate of the organic field-effect transistor is grounded, it can be known that the source-gate voltage is equal to the source voltage, that is, V SG = V S . Therefore, when determining the correspondence between the source voltage and the voltage gain of the organic field-effect crystal odor sensor according to the first correspondence and the second correspondence, formula 1 and formula 2 can be combined to obtain the correspondence between the source voltage and the voltage gain of the organic field-effect crystal odor sensor, as shown in formula 3:

[0113]

[0114] Among them, V S represents the source voltage, G represents the voltage gain, R1 represents the first resistor, V S represents the threshold voltage, V T represents the threshold voltage, W represents the width of the organic field-effect transistor, L represents the channel length of the organic field-effect transistor, C i represents the gate oxide capacitance per unit area.

[0115] The carrier mobility and the threshold voltage are obtained according to the corresponding relationship between the source voltage and the voltage gain of the organic field-effect crystal odor sensor.

[0116] In a specific implementation, the obtained source voltage V S and the voltage gain G are substituted into Formula 3, and the carrier mobility μ and the threshold voltage V T can be calculated.

[0117] To further determine the carrier mobility and the threshold voltage, the following steps are further included:

[0118] Obtain a relationship curve graph according to the corresponding relationship between the source voltage and the voltage gain of the organic field-effect crystal odor sensor;

[0119] Obtain the threshold voltage according to the intercept of the curve in the relationship curve graph;

[0120] Obtain the carrier mobility according to the slope of the relationship curve graph.

[0121] It should be noted that the relationship curve graph is a two-dimensional relationship image drawn from the corresponding relationship between the source voltage and the voltage gain, and the threshold voltage and the carrier mobility are obtained based on the intuitive representation of the two-dimensional relationship image.

[0122] In a specific implementation, first, according to different source voltages V S , according to the corresponding relationship G·V D =V S

[0123] calculate the voltage gain G, and then according to Formula 3, draw versus V S relationship curve graph, referring to Figure 5 , Figure 5 is versus V S relationship curve graph. The drawn image curve should be a straight line, and the abscissa of its intercept represents the threshold voltage V T , and its slope is related to is directly proportional, so that the threshold voltage V can be intuitively and quickly extracted from the drawn image. T and the charge carrier mobility μ.

[0124] To further determine the saturation current, the following steps are also included:

[0125] According to the corresponding relationship between the source voltage, the voltage gain, and the drain voltage, determine the corresponding relationship between the saturation current, the first resistor, and the drain voltage;

[0126] Obtain the saturation current based on the drain voltage and the first resistor.

[0127] In a specific implementation, according to the corresponding relationship G·V between the source voltage, the voltage gain, and the drain voltage D = V S , the corresponding relationship between the saturation current, the first resistor, and the drain voltage can be obtained. From G·V D = V S it can be seen that and combined with formula 4, V D = R1·I D,sat derive formula 1, and then the saturation current of the organic field effect transistor can be determined according to the drain voltage and the resistance value of the first resistor.

[0128] To further determine the voltage gain, the following steps are also included:

[0129] Determine the difference between the source voltage and the drain voltage according to the source voltage and the drain voltage;

[0130] Obtain the resistance adjustment instruction sent by the mobile terminal according to the difference;

[0131] Adjust the adjustable resistor to the target resistance value according to the resistance adjustment instruction;

[0132] Determine the voltage gain according to the target resistance value and the fixed resistor resistance value.

[0133] It should be noted that the difference between the source voltage and the drain voltage refers to the difference between the signal source voltage and the drain voltage displayed by the oscilloscope. For example, when the source voltage is +3V and the drain voltage displayed by the oscilloscope is +2.5V, the difference between them is 0.5V.

[0134] It can be understood that the adjustment instruction refers to the instruction to adjust the resistance value of the adjustable resistor to the mobile terminal when there is a difference between the source voltage and the drain voltage.

[0135] It should be understood that the voltage gain is adjusted by the mobile terminal for the adjustable resistor, so that the negative feedback circuit of the second operational amplifier adjusts the voltage amplification effect.

[0136] In a specific implementation, when there is a difference between the source voltage and the drain voltage and an instruction for adjusting the resistance value of the adjustable resistor is generated, the magnification of the drain voltage amplified by the second operational amplifier in the feedback circuit is adjusted when the instruction is received, so that the amplified drain voltage is equal to the source voltage. In the adjustment of specific voltage disputes, according to the source voltage and the drain voltage, and according to the corresponding relationship G·V D =V S the value to which the voltage gain needs to be adjusted is determined, and according to this value, the resistance value of the adjustable resistor that needs to be adjusted to the corresponding value is calculated. The calculation formula is as follows:

[0137]

[0138] where G is the voltage gain, R fiix is the fixed resistor, and R trim is the adjustable resistor. Therefore, by adjusting the adjustable resistor, the accurate adjustment of the voltage gain can be realized.

[0139] In order to further obtain the change in the charge carrier mobility and the change in the threshold voltage, the following steps are further included:

[0140] Adjust the source voltage multiple times to obtain multiple relationship curves;

[0141] Obtain multiple charge carrier mobilities and multiple threshold voltages according to the multiple relationship curves;

[0142] Obtain the change in the charge carrier mobility and the change in the threshold voltage according to the multiple charge carrier mobilities and multiple threshold voltages.

[0143] In a specific implementation, by continuously adjusting the source, multiple relationship curves with V S are obtained, and from each relationship curve, the corresponding charge carrier mobility and threshold voltage are extracted, and the change in the charge carrier mobility and the threshold voltage is obtained according to the obtained charge carrier mobility and threshold voltage.

[0144] In this embodiment, food biogenic amines are sensed based on an organic field-effect transistor and an odor detection circuit, which causes changes in the internal characteristics of the organic field-effect transistor, thereby resulting in changes in the circuit voltage signal. The voltage gain of the feedback circuit is adjusted according to the voltage signal displayed on the oscilloscope, so that the voltage displayed on the oscilloscope is equal to the source voltage, realizing the adjustment of the voltage gain by the mobile terminal. And according to the relationship between the source voltage and the voltage gain, the changes in the charge carrier mobility and the threshold voltage are determined, and thus the detection result of the food biogenic amines is obtained based on the changes in the charge carrier mobility or the threshold voltage, achieving the purpose of rapid detection on-site.

[0145] It should be understood that the above is only an example for illustration and does not constitute any limitation to the technical solution of the present invention. In specific applications, those skilled in the art can set according to needs, and the present invention does not make any restrictions in this regard.

[0146] It should be noted that the above-described work process is only illustrative and does not limit the protection scope of the present invention. In actual applications, those skilled in the art can select some or all of them according to actual needs to achieve the purpose of the solution of this embodiment, and no restrictions are made here.

[0147] In addition, it should be noted that in this article, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or system. Without further limitations, the element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or system including that element.

[0148] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0149] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described embodiment method can be implemented by means of software plus a necessary general hardware platform. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product is stored in a storage medium (such as a read-only memory (ROM) / RAM, magnetic disk, optical disk), and includes several instructions for causing a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in various embodiments of the present invention.

[0150] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. An odor measurement method, characterized in that, The described odor measurement method is applied to an odor measurement circuit, which includes: a voltage input circuit, a coupling circuit, an organic field effect transistor odor sensor, a voltage dividing circuit, a feedback circuit, and a display circuit connected in sequence. The voltage dividing circuit includes a first resistor. The first end of the first resistor is connected to the drain of the organic field effect transistor odor sensor, and the second end of the first resistor is grounded. The feedback circuit is also connected to a mobile terminal. The feedback circuit includes a second operational amplifier, a fixed resistor, and a variable resistor. The organic field effect transistor odor sensor includes: a substrate, a source and a drain are arranged above the substrate, an organic semiconductor layer is arranged above the source and the drain, a biogenic amine sensitive layer is arranged above the organic semiconductor layer, a water droplet is arranged above the biogenic amine sensitive layer, and a gate is arranged above the water droplet. The odor measurement method includes the following steps: The coupling circuit couples the input voltage of the voltage input circuit with the organic field effect transistor odor sensor, so that the source voltage of the organic field effect transistor odor sensor is equal to the input voltage; The voltage dividing circuit makes the source voltage of the organic field effect transistor odor sensor equal to the source-drain voltage; The display circuit displays the drain voltage of the organic field effect transistor odor sensor; The feedback circuit amplifies the drain voltage and adjusts the resistance through the mobile terminal until the amplified drain voltage is equal to the source voltage; Determine the voltage gain according to the source voltage and the drain voltage; Determine the charge carrier mobility and the threshold voltage according to the source voltage and the voltage gain; Adjust the source voltage multiple times to obtain the change of the charge carrier mobility and the change of the threshold voltage; Obtain the biogenic amine odor measurement result according to the change of the charge carrier mobility or the change of the threshold voltage.

2. The method according to claim 1, wherein The determining the charge carrier mobility and the threshold voltage according to the source voltage and the voltage gain of the organic field effect transistor includes: Obtain the first correspondence relationship with the saturation current according to the source voltage and the voltage gain; Obtain the second correspondence relationship with the saturation current according to the charge carrier mobility, the threshold voltage, and the source voltage; Obtain the correspondence relationship between the source voltage and the voltage gain of the organic field effect crystal odor sensor according to the first correspondence relationship and the second correspondence relationship; Obtain the charge carrier mobility and the threshold voltage according to the correspondence relationship between the source voltage and the voltage gain of the organic field effect crystal odor sensor.

3. The method according to claim 2, wherein The obtaining the charge carrier mobility and the threshold voltage according to the correspondence relationship between the source voltage and the voltage gain of the organic field effect crystal odor sensor includes: Obtain a relationship curve graph according to the correspondence relationship between the source voltage and the voltage gain of the organic field effect crystal odor sensor; Obtain the threshold voltage according to the intercept of the curve in the relationship curve graph; Obtain the charge carrier mobility according to the slope of the relationship curve graph.

4. The method according to claim 2, characterized in that, The obtaining the saturation current according to the source voltage and the voltage gain includes: Determine the corresponding relationship between the saturation current, the first resistor, and the drain voltage according to the corresponding relationship between the source voltage, the voltage gain, and the drain voltage; Obtain the saturation current based on the drain voltage and the first resistor.

5. The method according to claim 1, characterized in that, The determining of the voltage gain according to the source voltage and the drain voltage includes: Determine the difference between the source voltage and the drain voltage according to the source voltage and the drain voltage; Obtain the resistance adjustment instruction sent by the mobile terminal according to the difference; Adjust the adjustable resistor to the target resistance value according to the resistance adjustment instruction; Determine the voltage gain according to the target resistance value and the fixed resistor value.

6. The method according to any one of claims 1-5, characterized in that, The multiple adjustments of the source voltage to obtain the change in the charge carrier mobility and the change in the threshold voltage include: Make multiple adjustments to the source voltage to obtain multiple relationship curves; Obtain multiple charge carrier mobilities and multiple threshold voltages according to the multiple relationship curves; Obtain the change in the charge carrier mobility and the change in the threshold voltage according to the multiple charge carrier mobilities and the multiple threshold voltages.

7. The odor measurement method according to claim 1, wherein The coupling circuit includes a first operational amplifier; The output terminal of the voltage input circuit is connected to the non-inverting input terminal of the first operational amplifier, the inverting input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is connected to the source of the organic field effect transistor odor sensor.

8. The odor measurement method according to claim 1, wherein The non-inverting input terminal of the second operational amplifier is connected to the drain of the organic field effect transistor odor sensor, the output terminal of the second operational amplifier is connected to the first end of the fixed resistor, the second end of the fixed resistor is connected to the inverting input terminal of the second operational amplifier, the output terminal of the second operational amplifier is connected to the first end of the display circuit, the second end of the display circuit is grounded, the second end of the fixed resistor is connected to the first end of the adjustable resistor, the adjustable end of the adjustable resistor is connected to the mobile terminal, the second end of the adjustable resistor is grounded, and the gate of the organic field effect transistor odor sensor is grounded.

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