Mentha spicata volatile gas concentration detection system based on image colorimetric analysis

Abstract

The invention discloses a spearmint volatile gas concentration detection system based on image colorimetric analysis, and belongs to the technical field of colorimetric sensing analysis. The device is composed of an image sensing module, an image processing module, a control circuit module, a serial port screen display module, a baffle rotating speed motor, a conveying belt driving motor, a conveying belt and a fixed baffle, and the control circuit module is composed of two DRV8825 stepping motor driving modules, two EL357N optocoupler isolation modules and a single-chip microcomputer minimum system. The single-chip microcomputer minimum system is composed of an STM32 microprocessor, a reset module, a clock module and a power supply module. The image processing module is a computer program solidified in an STM32 microprocessor, and the serial port screen display module is composed of a UART serial port screen and used for data transmission and display. Based on the colorimetric sensing array taking gold nanoparticles as a main part, the advantages and disadvantages of spearmint plants can be judged in combination with an autonomous visual acquisition and analysis model, so that automatic and rapid sorting is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of colorimetric sensing analysis, and in particular relates to a spearmint volatile gas concentration detection system based on image colorimetric analysis. Background Art

[0002] Spearmint has attracted the attention of researchers because of its multiple medical effects and its ability to meet the treatment needs of different patients. Its potential volatile markers include gases such as L-carvone, limonene, and eucalyptol. From the upgrade of spearmint toothpaste to spearmint sleep essential oil, memory enhancement capsules rich in spearmint and other products, the demand for high-quality spearmint has gradually increased. When spearmint is damaged, gases including L-carvone, limonene, and eucalyptol will evaporate. By detecting the types and concentrations of volatile gases such as L-carvone, limonene, and eucalyptol, the damage process of the spearmint plant can be determined, so that the spearmint plants with severe damage can be excluded from the detection system. That is, combined with the background of fully mechanized harvesting, the automatic screening of highly damaged plants can more efficiently put healthy spearmint into the medical field.

[0003] The colorimetric sensor based on gold nanoparticles has the advantages of intuitive visualization, fast analysis speed, high response value, etc., and can have different RGB responses to various volatile organic gases (VOCs). Since the RGB data presented by the colorimetric array is diverse and complex, designing a spearmint volatile gas concentration detection system based on image colorimetric analysis can greatly improve its detection efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a spearmint volatile gas concentration detection system based on image colorimetric analysis.

[0005] The present invention is based on a colorimetric sensor array based on gold nanoparticles, combined with an autonomous visual acquisition and analysis model, which can judge the quality of spearmint plants, thereby achieving automatic and rapid sorting. The detection system of the present invention is composed of an image sensor module, an image processing module, a control circuit module, a serial port screen display module, a baffle speed motor, a conveyor belt drive motor, a conveyor belt and a fixed baffle. The image processing module is a computer program solidified in an STM32 microprocessor. Specifically:

[0006] (1) The image sensor module consists of a colorimetric sensor array (CSA) and a high-definition camera (HD) with a USB interface. The high-definition camera (HD) is connected to the STM32 microprocessor via the USB interface. The high-definition camera (HD) is set at a fixed position above the conveyor belt. Since the color change of the colorimetric sensor array is irreversible, a set of colorimetric sensor arrays must be set for each spearmint plant. The spearmint plant and the colorimetric sensor array are placed close to each other and then placed on the conveyor belt. The conveyor belt conveys the spearmint plant and the colorimetric sensor array to the bottom of the high-definition camera under the control of the conveyor belt drive motor. Spearmint plants with different degrees of damage will produce volatile gases of different concentrations, so the colorimetric sensor array will present different colors. The high-definition camera collects images of the colorimetric sensor array and transmits the images to the image processing module in the STM32 microprocessor via the USB interface.

[0007] The colorimetric sensing array consists of 9 groups of colorimetric dye solutions, the first group is gold nanoparticle solution AuNPs, the second and third groups are two kinds of glutamic acid modified gold nanoparticle (GA-AuNPs) solutions, the fourth group is chitosan modified gold nanoparticle (CS-AuNPs) solution, the fifth group is cysteine ​​modified gold nanoparticle (Cys-AuNPs) solution, the sixth group is methylene blue-methyl red reagent, the seventh group is bromothymol blue-neutral red reagent, and the eighth group is 2,4-dinitrophenylhydrazine reagent, group 9 is o-toluidine reagent; the difference between the two glutamic acid modified gold nanoparticles (GA-AuNPs) is that the volume of 0.01mM glutamic acid (GA) dropped into 5mL of gold nanoparticle (AuNPs) solution is different, 200mL and 600mL respectively; among them, group 6 and group 7 are pH indicators, group 8 reagents are mainly used to test aldehydes and ketones; group 9 reagents can be used as dyes for colorimetric detection. Due to the unique surface plasmon resonance (SPR) properties of gold nanoparticles (AuNPs), the introduction of organic volatile gases will cause the particles to aggregate, the distance between the nanoparticles will decrease, the surface plasmon resonance effect will be enhanced, and the LSPR absorption peak will move toward the long wavelength direction (i.e., red shift), causing the color of AuNPs to gradually change from red to purple or blue. The preliminary results of this experiment show that single AuNPs can show RGB difference signals under the same concentration and different VOCs. That is, at a concentration of 100ppm, except for Eucalyptol, other VOCs (L-carvone, dihydrocarvone, dihydrocarvyl acetate, limonene, and myrcene) can cause the LSPR absorption peak of AuNPs to red-shift, and the red-shift of L-carvone is the most obvious. Various ligand-modified gold nanoparticles (including glutamic acid-modified gold nanoparticles (GA-AuNPs), chitosan-modified gold nanoparticles (CS-AuNPs), and cysteine-modified gold nanoparticles (Cys-AuNPs)) can inhibit the aggregation of gold nanoparticles by VOCs, which will hinder the red-shift of the LSPR absorption peak of AuNPs;

[0008] (2) the image processing module obtains the RGB signal at the exact center of the image, and quantifies the difference between the colors by calculating the color difference (ΔΕi) of each colorimetric sensing solution, and then performs signal classification and concentration quantification to correspond to the state of the spearmint; wherein,

[0009]

[0010] Wherein, ΔRi, ΔGi, and ΔBi are the differences between the RGB value of the center point of the image of the i-th colorimetric sensor array (CSA) in the presence of a normal plant or a damaged plant and the RGB value of the center point of the image of the colorimetric sensor array (CSA) in the absence of a plant, respectively, i=1-9;

[0011] (3) The serial port screen display module is mainly composed of a UART serial port screen, which transmits data with the STM32 microprocessor through serial port communication, receives instructions from the STM32 microprocessor and completes the display function; the UART serial port screen can realize the touch screen button function according to the interface design, that is, the operation instructions can be input by touching the buttons, thereby realizing information interaction between the device and the inspector. The UART serial port screen is used as an asynchronous transceiver transmitter to communicate with the STM32 microprocessor. The DBG_TXD1 data transmission terminal of the STM32 microprocessor is connected to the RXD data reception terminal of the UART serial port screen, and the DBG_RXD1 data reception terminal of the STM32 microprocessor is connected to the TXD data transmission terminal of the UART serial port screen to receive and display data. The display content includes the following aspects: name (spearmint), production place (Changchun, Jilin), main ingredients (especially VOCs with high concentrations) and taboos, etc. The STM32 microprocessor determines the state of the spearmint according to the calculation result in step (2). The determination lines of ΔEi of the 9 groups of colorimetric solutions are all different. The sum (ΔE) of the 9 ΔΕi (i=1~9) values ​​can be combined to infer the three states of the spearmint plant, namely,

[0012] ΔE=ΔE1+ΔE2+ΔE3+ΔE4+ΔE5+ΔE6+ΔE7+ΔE8+ΔE9

[0013] After multiple experiments, it was verified that when there are no plants on the conveyor belt, ΔE=0; when the plants on the conveyor belt are normal and undamaged, ΔE=180-360. Since the ΔE value of the colorimetric solution of mature plants is higher than that of young plants, ΔE will have a larger numerical range when the plants are normal; when ΔE>360, the plants on the conveyor belt are damaged. When the ΔE value is less than 180, it indicates that the colorimetric sensor array is damaged and normal colorimetric detection cannot be performed, and it is set to "State 1"; when the ΔE value is greater than 180 and less than 360, it indicates that the concentration of volatile gases is at an upper-middle level, but the plant sample is not damaged, and it is set to "State 2"; when the ΔE value is greater than 360, it indicates that the concentration of volatile gases is at a high level, and the plant sample is damaged at this time, and it is set to "State 3"; "State 3" indicates unqualified plants;

[0014] (4) The control circuit module consists of two DRV8825 stepper motor drive modules, two EL357N optocoupler isolation modules and a single-chip minimum system. The single-chip minimum system consists of an STM32 microprocessor, a reset module, a clock module and a power module.

[0015] The power module converts the 12V voltage into 5V voltage through the K7805MT-1000R4 power chip, and then converts the 5V voltage into 3.3V voltage for use by the STM32 microprocessor through the PS1117-3.3 chip; Pin 1 of the K7805MT-1000R4 power chip is the external power input terminal, and the 12V external power supply is connected to pin 1 through the Schottky diode D4 and the fuse F1, and pin 2 is the common (negative) ground GND. Connect a Zener diode TV9, a 470uF electrolytic capacitor C1 and a 10uF chip capacitor C30 in parallel between pin 1 and pin 2, wherein the cathode of the Zener diode TV9 is connected to pin 1 and the anode is connected to pin 2, the anode of the 470uF electrolytic capacitor C1 is connected to pin 1 and the cathode is connected to pin 2; Pin 3 is the output terminal, outputting a 5V voltage; connect a Zener diode D, 22uF chip capacitors C23 and C24 in parallel between pin 3 and ground GND, the cathode of the Zener diode D3 is connected to pin 3, and the anode is connected to ground GND. Pin 3 of the PS1117-3.3 chip is the INPUT input terminal and is connected to the 5V voltage output by pin 3 of the K7805MT-1000R4 power chip. A 0.1uF chip capacitor C17 and a 1uF chip capacitor C11 are connected in parallel between pin 3 and the ground GND. Pin 1 of the PS1117-3.3 chip is connected to the ground GND. Pin 2 is the OUTPUT terminal, which outputs a 3.3V voltage. A 0.1uF chip capacitor C18 and a 47uF chip capacitor C16 are connected in parallel between pin 2 and the ground GND to ensure a stable output voltage. DC005-2.0MM is a DC connector, and KF2EDGV-5.08-2P is a 2-pin terminal block, which is convenient for circuit connection and suitable for quick connection and disconnection.

[0016] The use of EL357N optocoupler isolation module makes the STM32 microprocessor unaffected by the two DRV8825 stepper motor driver modules. The pin configuration and function of the EL357N optocoupler isolation module make it a very practical isolator to prevent the high voltage in the stepper motor driver module from affecting the STM32; it can also be used for the STM32 microprocessor to drive the stepper motor, that is, to control the circuit through a smaller current. There are two EL357N optocoupler isolation modules, both of which are composed of infrared light-emitting diodes (infrared LEDs) and NPN phototransistors. When the infrared LED is powered, the infrared LED emits light, and the light falls on the base of the NPN phototransistor, making it activated, and finally converting the electrical signal into an optical signal and then into an electrical signal output; the EL357N optocoupler isolation module includes 4 pins, pin 1 is the positive pole of the infrared LED, pin 2 is the negative pole of the infrared LED, pin 3 is the emitter e of the NPN phototransistor, and pin 4 is the collector c of the NPN phototransistor. The infrared LED of the EL357N optocoupler isolation module is a low-voltage input source. Resistor R62 and chip capacitor C36 are connected in parallel between the positive and negative electrodes of the infrared LED. When the input current passes through the infrared LED after passing through resistor R65 (CN3 and CN4 are HT508R-5.08-3P wiring terminals, which are convenient for connection between wires), the LED will emit infrared light; the NPN phototransistor is a high-voltage output source. When the NPN phototransistor receives an infrared light signal, it will generate a current output from pin 4. This current can be used to drive a stepper motor. In one EL357N optocoupler isolation module, the 3.3V voltage output from pin 2 of the PS1117-3.3 chip is connected to the collector c of the NPN phototransistor and the INPUT_1 pin of the STM32 microprocessor through a 10K resistor R5, and the emitter e of the NPN phototransistor is grounded to GND; in another EL357N optocoupler isolation module, the 3.3V voltage output from pin 2 of the PS1117-3.3 chip is connected to the collector c of the NPN phototransistor and the INPUT_2 pin of the STM32 microprocessor through a 10K resistor R6, and the emitter e of the NPN phototransistor is grounded to GND. The INPUT_1 pin of the STM32 microprocessor is defined as PB5, and the INPUT_2 pin is defined as PB6.

[0017] The DRV8825 stepper motor driver module adopts a dual H-bridge structure, which can control the speed and direction of rotation of the motor by adjusting the duty cycle of the input signal from the STM32 microprocessor. The DRV8825 module has a total of 16 pins, pin 1 is grounded GND, pin 2 is FLT connected to resistor R8 to prevent overheating and overcurrent; pins 3 to 6 correspond to 2A, 1A, 1B, 2B, respectively, connecting windings A and B of the stepper motor; windings A and B can generate magnetic fields by energizing, interact with the fixed magnetic poles of the stepper motor, thereby generating torque and driving the motor to rotate; by accurately controlling the power-on time and sequence of windings A and B, the step angle and speed control of the motor can be achieved. Pin 14 is SLEEP high level for normal energy consumption mode, while pin 13 is RESET by default high level. Pin 14 and pin 13 are connected through 1k resistor R4 and then connected to the 3.3V voltage output by pin 2 of the PS1117-3.3 chip. Among them, the DIR pin 16 of the DRV8825 motor controls the direction of rotation of the motor. The high and low level conversion of pin 16 can make the stepper motor change from clockwise to counterclockwise rotation; STPE pin 15 can control the speed of the stepper motor and is used to receive the step pulse signal of the STM32 microprocessor. Pins 10 to 12 are MOOD pins corresponding to M0, M1, and M2 respectively. The three together form a 3-bit binary number, which is connected to the 3.3V voltage through 10K resistors R1, R2, and R3 respectively; users can set 6 subdivision modes through the MOOD pin, which include full step, 1 / 2 step, 1 / 4 step, 1 / 8 step, 1 / 16 step, and 1 / 32 step; by the built-in pull-down function, that is, when these pins are not connected to external signals, they are in a low level state by default, thereby ensuring that the chip is in a safe or predefined state when it is powered on or not configured. The present invention is provided with two DRV8825 stepper motor drive modules, one DRV8825 stepper motor drive module is used to drive the conveyor belt control motor 9, which is used to control the movement of the conveyor belt; when the colorimetric sensor array on the conveyor belt and the spearmint plant reach the bottom of the high-definition camera 2, the conveyor belt stops moving, the high-definition camera 2 collects images from the colorimetric sensor array, and then transmits the collected images to the image processing module in the STM32 microprocessor for subsequent data analysis; after the high-definition camera 2 collects images from the colorimetric sensor array , the conveyor belt continues to move; another DRV8825 stepper motor driver module is used to drive the baffle control motor 3. When the ΔE value is greater than 360, the STM32 microprocessor pin 64 sends a high level signal (EN2=1), and the DRV8825 stepper motor driver module pin 9 receives the high level signal (EN2=1), and then drives the baffle control motor 3 to work, and then pushes the unqualified plants and the colorimetric sensor array out of the conveyor belt 100 in the vertical direction through the fixed baffle 5, that is, the spearmint plants of different qualities are sorted according to the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 : Schematic diagram of the mechanical structure of the spearmint volatile gas concentration detection system based on image colorimetric analysis of the present invention; names of various parts: serial port display screen 1, high-definition camera 2, high-definition camera bracket 21, baffle speed motor 3, baffle speed motor rotating wheel 31, upper rear support frame 4, upper front support frame 41, fixed baffle 5, lower support frame 6, control circuit module 7, colorimetric sensor array 8, fixed upper and lower rod door frame 110, conveyor belt drive motor 9, conveyor belt drive motor upper rotating wheel 91, conveyor belt drive motor bottom rotating wheel 92, conveyor belt 100; image sensor module is composed of high-definition camera 2 and colorimetric sensor array 8;

[0019] There are two fixed upper and lower rod door frames 110, which are respectively located at the two ends of the detection system; the lower end support frame 6 is horizontally arranged and installed between the lower inner side surfaces of the two fixed upper and lower rod door frames 110, and the upper end rear support frame 4 and the upper end front support frame 41 are respectively installed between the upper inner side surfaces of the two fixed upper and lower rod door frames 110. The two fixed upper and lower rod door frames 110, the lower end support frame 6, the upper end rear support frame 4 and the upper end front support frame 41 constitute the framework structure of the detection system. The serial port display screen 1 is arranged on the upper end front support frame 41, and is connected to the STM32 microprocessor in the control circuit module 7 through a USB to Type-c module for receiving and displaying data; the high-definition camera bracket 21 is connected between the upper end rear support frame 4 and the upper end front support frame 41, and the high-definition camera 2 is placed in the middle of the high-definition camera bracket 21, and the vertical height from the upper end rear support frame 4 is 5cm.

[0020] A control circuit module 7 is provided between the upper front support frame 41 and the lower support frame 6. Figure 3 The circuit shown, i.e., the control circuit module 7, is composed of two DRV8825 stepper motor drive modules, two EL357N optocoupler isolation modules and a single-chip minimum system, and the single-chip minimum system is composed of an STM32 microprocessor, a reset module, a clock module and a power module.

[0021] The conveyor belt drive motor 9, the upper rotating wheel 91 of the conveyor belt drive motor and the bottom rotating wheel 92 of the conveyor belt drive motor are arranged in the fixed upper and lower rod door frame 110 on the left side. The conveyor belt 100 is installed on the lower end support frame 6, and the conveyor belt drive motor 9 controls the movement of the conveyor belt 100 by driving the upper rotating wheel 91 of the conveyor belt drive motor and the bottom rotating wheel 92 of the conveyor belt drive motor. A baffle speed motor 3 is arranged between the upper front support frame 41 and the upper rear support frame 4, a fixed baffle 5 is arranged above the conveyor belt 100, and a baffle speed motor rotating wheel 31 is arranged in the fixed upper and lower rod door frame 110 on the right; the baffle speed motor 3 can control the fixed baffle 5 to move vertically along the conveying direction perpendicular to the conveyor belt 100 through the baffle speed motor rotating wheel 31 (the baffle speed motor 3 controls the rotation direction of the motor through the DIR pin 16 of the DRV8825 motor, and the STPE pin 15 can control the speed of the stepper motor to make the fixed baffle 5 move in the direction perpendicular to the conveyor belt), so that the unqualified plants and the colorimetric sensor array are pushed out from the conveyor belt 100 according to the control instructions received from the STM32 microprocessor. The colorimetric sensor array 8 and the spearmint plant are placed on the conveyor belt 100 together, and the colorimetric sensor array 8 and the spearmint plant move together with the conveyor belt 100.

[0022] Figure 2 : A working block diagram of the detection system of the present invention;

[0023] like Figure 2 As shown, the single-chip minimum system cooperates with the image sensor module, the motor drive control module, the optical coupling module, the indicator light module, the buzzer module, and the serial port screen display module. When the touch screen button in the serial port screen is pressed, the buzzer module makes a sound, and the program in the STM32 microprocessor starts; the USB external high-definition camera transmits the image of the colorimetric sensor array to the STM32 microprocessor for data storage, and then the image processing module solidified in the STM32 microprocessor calculates the RGB value of the center point of the image, and calculates the color difference value ΔΕi, and determines the detection result according to the range of the color difference ΔΕ, and the detection result is passed into the serial port screen, and the movement of the baffle speed motor 3 is driven.

[0024] Figure 3 : Circuit schematic diagram of the control circuit module of the present invention;

[0025] like Figure 3 As shown, it includes two DRV8825 stepper motor drive modules, two EL357N optocoupler isolation modules and a single-chip minimum system (consisting of an STM32 microprocessor, a reset module, a clock module and a power module). DETAILED DESCRIPTION

[0026] Example 1

[0027] By using the color value response of colorimetric dyes to volatile organic gases, a dynamic detection system based on a colorimetric sensor array with gold nanoparticles was successfully prepared. The spearmint plants of different qualities were displayed and sorted according to the detection results. The process is as follows:

[0028] (1) Preparation of AuNPs-based colorimetric sensor: Gold nanoparticles (AuNPs) were prepared by reducing chloroauric acid solution with sodium citrate. 1 mL of 0.1 mol / L chloroauric acid solution (purity 99%) was placed in a 200 mL beaker, 100 mL of deionized water was added, and a magnet was placed in the beaker. The beaker was placed in an oil bath heating pot, and the oil bath temperature was set to 110°C and heated to boiling. While stirring rapidly (stirring speed was 1200 rpm), 0.114 g of sodium citrate dihydrate powder was added to 10 mL of deionized water to prepare a sodium citrate solution, which was then quickly added to the chloroauric acid solution. After stirring vigorously for 10 min, the heating switch was turned off, and stirring was continued for 15 min. The solution was cooled to room temperature, and its color changed from light yellow to red, and a 70 nm wine red gold nanoparticle solution was finally obtained. 1 mM glutamic acid (200 μL and 600 μL, respectively), chitosan (200 μL), and cysteine ​​(200 μL) were added to 5 mL of the gold nanoparticle solution to prepare two groups of glutamic acid-modified gold nanoparticle (GA-AuNPs) solutions, one group of chitosan-modified gold nanoparticle (CS-AuNPs) solutions, and one group of cysteine-modified gold nanoparticle (Cys-AuNPs) solutions;

[0029] (2) Make a spearmint volatile gas concentration detection system: Use the K7805MT-1000R4 power module to convert the 12V external power supply into a stable 5V power supply, and then add the PS1117-3.3 voltage conversion chip to convert the 5V voltage into a stable 3.3V voltage for the STM32 microprocessor. The components used include Schottky diodes, voltage regulator diodes, chip capacitors, chip resistors and electrolyte capacitors. The EL357N optocoupler isolation module is used to isolate the pulse signal output by the STM32 so that the STM32 microprocessor is not affected by the DRV8825 motor. The DRV8825 stepper electrode driver module can control the motor speed (STPE pin 15) and direction (DIR pin 16) by adjusting the duty cycle of the control input signal. This system uses two motor drivers, one motor controls the start and stop of the conveyor belt, and the other motor controls the sorting results. Plants of different types are reasonably placed and stacked, and the fixed baffle 5 can push the plants in the direction perpendicular to the conveyor belt. The start and stop of the conveyor belt includes the following stages: Stage 1 starts the program and starts running; Stage 2 reaches the specified position scanned by the camera, the motor stops rotating, and the high-definition camera collects the image of the colorimetric array; Stage 3 After the delay is over, click to start rotating and continue running; Stage 4 runs to the sorting motor part, starts and stops according to the analysis results. At this time, the start and stop are related to the action of the baffle.

[0030] (3) A high-definition camera collects images from the colorimetric sensor array and transmits the images to the image processing module in the STM32 microprocessor through a USB interface; the sum of the nine ΔΕi (i=1-9) values ​​(ΔΕ) can be used to infer the three states of the spearmint plant, namely,

[0031] ΔE=ΔE1+ΔE2+ΔE3+ΔE4+ΔE5+ΔE6+ΔE7+ΔE8+ΔE9

[0032] After multiple experiments, it was verified that when there were no plants on the conveyor belt, ΔE=0; when the plants on the conveyor belt were normal and undamaged, ΔE=180-360. Since the ΔE value of the colorimetric solution of mature plants is higher than that of young plants, ΔE will have a larger numerical range when the plants are normal; when ΔE>360, the plants on the conveyor belt are damaged. When the ΔE value is less than 180, it indicates that the colorimetric sensor array is damaged and normal colorimetric detection cannot be performed, which is set to "state 1"; when the ΔE value is greater than 180 and less than 360, it indicates that the concentration of volatile gases is at an upper-middle level, but the plant samples are not damaged, which is set to "state 2"; when the ΔE value is greater than 360, it indicates that the concentration of volatile gases is at a high level, and the plant samples are damaged at this time, which is set to "state 3"; "state 3" is an unqualified plant.

Claims

1. A spearmint volatile gas concentration detection system based on image colorimetric analysis, characterized in that: The detection system is composed of an image sensor module, an image processing module, a control circuit module, a serial port screen display module, a baffle speed motor (3), a conveyor belt drive motor (9), a conveyor belt (100) and a fixed baffle (5); the control circuit module is composed of two DRV8825 stepper motor drive modules, two EL357N optical coupling isolation modules and a single-chip minimum system; the single-chip minimum system is composed of an STM32 microprocessor, a reset module, a clock module and a power supply module; The image processing module is a computer program solidified in the STM32 microprocessor, and the serial port screen display module is composed of a UART serial port screen (1), which communicates with the STM32 microprocessor through the serial port to perform data transmission and display; (1) The image sensing module is composed of a colorimetric sensor array (8) and a high-definition camera (2) with a USB interface. The high-definition camera (2) is connected to an STM32 microprocessor via a USB interface. The high-definition camera (2) is arranged at a fixed position above a conveyor belt (100). The colorimetric sensor array is composed of 9 groups of colorimetric dye solutions. The spearmint plant and the colorimetric sensor array are placed close to each other and then placed together on the conveyor belt (100). The conveyor belt (100) conveys the spearmint plant and the colorimetric sensor array to the bottom of the high-definition camera (2) under the control of a conveyor belt drive motor (9). Spearmint plants with different degrees of damage will produce volatile gases of different concentrations, so the colorimetric sensor array (8) will present different colors. A high-definition camera (2) collects images from the colorimetric sensor array (8) and transmits the images to an image processing module in the STM32 microprocessor via a USB interface; (2) the image processing module obtains the RGB signal at the exact center of the image, and quantifies the difference between the colors by calculating the color difference (ΔΕi) of each colorimetric sensing solution, and then performs signal classification and concentration quantification to correspond to the state of the spearmint; wherein, Wherein, ΔRi, ΔGi, and ΔBi are the differences between the RGB value of the center point of the image of the i-th colorimetric sensor array (CSA) in the presence of a normal plant or a damaged plant and the RGB value of the center point of the image of the colorimetric sensor array (CSA) in the absence of a plant, respectively, i=1-9; (3) The STM32 microprocessor determines the state of the spearmint plant according to the calculation results in step (2). The determination lines of ΔEi of the nine groups of colorimetric solutions are all different. The sum ΔE of the nine ΔEi (i=1-9) values ​​can be used to infer the three states of the spearmint plant, namely, ΔE=ΔE1+ΔE2+ΔE3+ΔE4+ΔE5+ΔE6+ΔE7+ΔE8+ΔE9 When there are no plants on the conveyor belt (100), ΔE=0; when the plants on the conveyor belt (100) are normal and undamaged, ΔE=180-360; when ΔE>360, the plants on the conveyor belt (100) are damaged; when the ΔE value is less than 180, it indicates that the colorimetric sensor array is damaged and normal colorimetric detection cannot be performed, and it is set to "state 1"; when the ΔE value is greater than 180 and less than 360, it indicates that the concentration of volatile gases is at an upper-middle level, but the plant sample is not damaged, and it is set to "state 2"; when the ΔE value is greater than 360, it indicates that the concentration of volatile gases is at a relatively high level, and the plant sample is damaged, and it is set to "state 3"; (4) A DRV8825 stepper motor drive module drives a conveyor belt control motor (9) to control the movement of the conveyor belt (100); when the colorimetric sensor array (8) and the spearmint plant on the conveyor belt (100) reach below the high-definition camera (2), the conveyor belt (100) stops moving, the high-definition camera (2) acquires an image of the colorimetric sensor array (8), and then transmits the acquired image to an image processing module in the STM32 microprocessor for subsequent data analysis; after the high-definition camera (2) acquires an image of the colorimetric sensor array, the conveyor belt continues to move; another DRV8825 stepper motor drive module drives a baffle control motor (3), and when the ΔE value is greater than 360, the STM32 microprocessor drives the baffle control motor (3) to work, and then pushes the unqualified spearmint plant and the colorimetric sensor array (8) out of the conveyor belt (100) in a vertical direction through the fixed baffle (5), thereby realizing the concentration detection of spearmint volatile gas based on image colorimetric analysis.

2. The spearmint volatile gas concentration detection system based on image colorimetric analysis as claimed in claim 1, characterized in that: The power module converts the 12V voltage into 5V voltage through the K7805MT-1000R4 power chip, and then converts the 5V voltage into 3.3V voltage for use by the STM32 microprocessor through the PS1117-3.3 chip; Pin 1 of the K7805MT-1000R4 power chip is the external power input terminal, and the 12V external power supply is connected to pin 1 through the Schottky diode D4 and the fuse F1, and pin 2 is the common ground GND; Zener diode TV9, 470uF electrolytic capacitor C1 and 10uF chip capacitor C30 are connected in parallel between pin 1 and pin 2, where the negative pole of the Zener diode TV9 is connected to pin 1 and the positive pole is connected to pin 2, and the positive pole of the 470uF electrolytic capacitor C1 is connected to pin 1 and the negative pole is connected to pin 2; Pin 3 is the output terminal, which outputs 5V voltage; Zener diode D, 22u The cathode of the voltage zener diode D3 is connected to pin 3, and the anode is connected to ground GND; pin 3 of the PS1117-3.3 chip is the INPUT input terminal connected to the 5V voltage output by pin 3 of the K7805MT-1000R4 power chip, and a 0.1uF chip capacitor C17 and a 1uF chip capacitor C11 are connected in parallel between pin 3 and the ground GND; pin 1 of the PS1117-3.3 chip is connected to the ground GND; pin 2 is the OUTPUT terminal, which outputs a 3.3V voltage; a 0.1uF chip capacitor C18 and a 47uF chip capacitor C16 are connected in parallel between pin 2 and the ground GND to ensure a stable output voltage; DC005-2.0MM is a DC connector, and KF2EDGV-5.08-2P is a 2-pin terminal block, which is convenient for circuit connection and suitable for quick connection and disconnection.

3. The spearmint volatile gas concentration detection system based on image colorimetric analysis as claimed in claim 1, characterized in that: The use of EL357N optocoupler isolation module makes the STM32 microprocessor unaffected by the two DRV8825 stepper motor drive modules; there are two EL357N optocoupler isolation modules, both of which are composed of infrared LED and NPN phototransistor. When the infrared LED is powered, the infrared LED emits light, and the light falls on the base of the NPN phototransistor to activate it, and finally converts the electrical signal into an optical signal and then into an electrical signal output; the EL357N optocoupler isolation module includes 4 pins, pin 1 is the positive electrode of the infrared LED, pin 2 is the negative electrode of the infrared LED, pin 3 is the emitter e of the NPN phototransistor, and pin 4 is the collector c of the NPN phototransistor; the infrared LED of the EL357N optocoupler isolation module is a low-voltage input source, and the resistor R62 and the chip capacitor C36 are connected in parallel between the positive and negative electrodes of the infrared LED. When the input current passes through the infrared resistor R65 and then passes through the infrared When the LED is on, the LED will emit infrared light; the NPN phototransistor is a high-voltage output source. When the NPN phototransistor receives an infrared light signal, it will generate a current output from pin 4, which can be used to drive a stepper motor; in an EL357N optocoupler isolation module, the 3.3V voltage output from pin 2 of the PS1117-3.3 chip is connected to the collector c of the NPN phototransistor and the INPUT_1 pin of the STM32 microprocessor through a 10K resistor R5, and the emitter e of the NPN phototransistor is grounded to GND; in another EL357N optocoupler isolation module, the 3.3V voltage output from pin 2 of the PS1117-3.3 chip is connected to the collector c of the NPN phototransistor and the INPUT_2 pin of the STM32 microprocessor through a 10K resistor R6, and the emitter e of the NPN phototransistor is grounded to GND.

4. The spearmint volatile gas concentration detection system based on image colorimetric analysis as claimed in claim 1, characterized in that: The DRV8825 stepper motor driver module adopts a dual H-bridge structure, which can control the speed and direction of rotation of the motor by adjusting the duty cycle of the input signal from the STM32 microprocessor; the DRV8825 module has a total of 16 pins, pin 1 is grounded GND, pin 2 is FLT connected to resistor R8 to prevent overheating and overcurrent; pins 3 to 6 correspond to 2A, 1A, 1B, and 2B, respectively, to connect windings A and B of the stepper motor; windings A and B can generate magnetic fields by energizing, interact with the fixed magnetic poles of the stepper motor, thereby generating torque and driving the motor to rotate; by accurately controlling the power-on time and sequence of windings A and B, the step angle and speed control of the motor can be achieved; pin 14 is SLEEP high level for normal energy consumption mode, and pin 13 is RESET by default high level, pin 14 and pin 13 are connected after 1k resistor R4 and then connected to the PS1117-3.3 chip lead Pin 2 outputs a 3.3V voltage; the DIR pin 16 of the DRV8825 motor controls the direction of rotation of the motor, and the conversion of the high and low levels of pin 16 can make the stepper motor change from clockwise to counterclockwise rotation; STPE pin 15 can control the speed of the stepper motor and is used to receive the step pulse signal of the STM32 microprocessor; pins 10 to 12 are MOOD pins corresponding to M0, M1, and M2 respectively, and the three together form a 3-bit binary number, which are connected to the 3.3V voltage with 10K resistors R1, R2, and R3 respectively; users can set 6 subdivision modes through the MOOD pin, which include full step, 1 / 2 step, 1 / 4 step, 1 / 8 step, 1 / 16 step, and 1 / 32 step; by the built-in pull-down function, that is, when these pins are not connected to external signals, they are in a low level state by default, thereby ensuring that the chip is in a safe or predefined state when it is powered on or not configured.

5. The spearmint volatile gas concentration detection system based on image colorimetric analysis as claimed in claim 1, characterized in that: The colorimetric sensing array consists of 9 groups of colorimetric dye solutions, the first group is gold nanoparticle solution AuNPs, the second and third groups are two glutamic acid-modified gold nanoparticle solutions, the fourth group is chitosan-modified gold nanoparticle solution, the fifth group is cysteine-modified gold nanoparticle solution, the sixth group is methylene blue-methyl red reagent, the seventh group is bromothymol blue-neutral red reagent, the eighth group is 2,4-dinitrophenylhydrazine reagent, and the ninth group is o-toluidine reagent; among them, the difference between the two glutamic acid-modified gold nanoparticles is that the volume of 0.01mM glutamic acid dripped into 5mL of gold nanoparticle solution is different, which are 200mL and 600mL respectively; among them, the sixth and seventh groups are pH indicators, the eighth group of reagents is mainly used to detect aldehydes and ketones; the ninth group of reagents can be used as a dye for colorimetric detection.

6. The spearmint volatile gas concentration detection system based on image colorimetric analysis as claimed in claim 1, characterized in that: The detection system is also equipped with a baffle speed motor rotating wheel (31), an upper rear support frame (4), an upper front support frame (41), a lower support frame (6), a fixed upper and lower rod door frame (110), an upper rotating wheel (91) of a conveyor belt drive motor, and a bottom rotating wheel (92) of a conveyor belt drive motor; there are two fixed upper and lower rod door frames (110), which are respectively located at two ends of the detection system; the lower support frame (6) is horizontally arranged and installed between the lower parts of the inner side surfaces of the two fixed upper and lower rod door frames (110), and the upper rear support frame (4) and the upper front support frame (41) are respectively installed on the two The two fixed upper and lower rod door frames (110), the lower support frame (6), the upper rear support frame (4) and the upper front support frame (41) constitute the framework structure of the detection system; the serial port display screen (1) is arranged on the upper front support frame (41) and is connected to the STM32 microprocessor in the control circuit module (7) through a USB to Type-c module for receiving and displaying data; the high-definition camera bracket (21) is connected between the upper rear support frame (4) and the upper front support frame (41); the high-definition camera ( 2) is placed in the middle of the high-definition camera bracket (21); the control circuit module (7) is arranged between the upper front support frame (41) and the lower support frame (6); a conveyor belt drive motor (9), an upper rotating wheel (91) of the conveyor belt drive motor and a bottom rotating wheel (92) of the conveyor belt drive motor are installed in the fixed upper and lower rod door frame (110) on the left; the conveyor belt (100) is installed on the lower support frame (6), and the conveyor belt drive motor (9) controls the conveyor belt (100) by driving the upper rotating wheel (91) of the conveyor belt drive motor and the bottom rotating wheel (92) of the conveyor belt drive motor. movement; a baffle speed motor (3) is installed between the upper front support frame (41) and the upper rear support frame (4), a fixed baffle (5) is installed above the conveyor belt (100), and a baffle speed motor rotating wheel (31) is installed in the fixed upper and lower rod door frame (110) on the right; the baffle speed motor (3) controls the fixed baffle (5) to move vertically along the conveying direction perpendicular to the conveyor belt (100) through the baffle speed motor rotating wheel (31), so that unqualified plants and colorimetric sensor arrays are pushed out from the conveyor belt (100) according to the control instructions received from the STM32 microprocessor.

Images