CN104865186B - Portable pathogenic bacteria quick determination method - Google Patents

Abstract

The invention discloses a kind of portable pathogenic bacteria quick determination method, including step 1, magnetic bead is added in test substance, test substance is put into heating tank heated at constant temperature is carried out by temperature control unit, nucleic acid extraction module is put into test substance, the magnetic bead for adsorbing nucleic acid is suctioned out according to the magnetic force area of nucleic acid extraction module；Step 2, test substance is heated by heater, step 3, laser transmitter projects laser, laser is radiated on test substance through laser vias, laser sensor receives the laser passed from laser vias, and after being analyzed by control board, the detection data of test substance are shown in display module.The present invention embodies economy and portability, detects precise and high efficiency.

Description

Portable rapid detection method for pathogenic bacteria

technical field

The invention relates to the field of automatic control, in particular to a portable rapid detection method for pathogenic bacteria.

Background technique

In recent years, due to the frequent occurrence of foodborne pathogenic microorganism poisoning incidents, the mutation or cross-border transmission of animal and plant pathogens, and the safety of genetically modified ingredients, biosafety issues have become more and more prominent. Detection technology and detection equipment in the field of biosafety have become one of the research hotspots. For example, in 2013, New Zealand's "botulism" milk powder incident and Germany's "poisonous cucumber" and "adulterated horse meat ingredients" incidents occurred, resulting in the deteriorating food safety situation at home and abroad. In this context, any rapid detection technology that is beneficial to pathogenic microorganisms and their genetic components has great application value and market prospects.

The invention aims to develop a portable gene amplification detection device, which first uses a hand-held magnetic frame to extract nucleic acid DNA in a sample, then uses a constant temperature incubator to perform nucleic acid amplification, and uses a miniature photoelectric detector to analyze and interpret the results . The equipment developed by the present invention is not only special in principle, but also light and portable, and its cost is lower than that of similar biological gene detection equipment on the market. For example, DuPont's The Q7 automatic rapid detection system for pathogenic microorganisms uses the principle of fluorescent quantitative PCR to detect microorganisms. The system BAXQ 7 weighs up to 40 kg and sells for more than 400,000 RMB. Another example is the BioLumix 32 of BioLumix Company of the United States, which adopts 32 parallel detection tubes, and detects through photosensitive reagents according to the chemical characteristic changes in the microbial liquid culture medium. The Biolumix32 system weighs 14 kg. Not to mention the sensitivity and accuracy of the above-mentioned commercial system, in terms of its weight and selling price, it is not suitable for on-site detection of food microorganisms. The real-time turbidimeter and other ordinary PCR instruments of Japan's Eiken Company can also be applied to the rapid detection of the genes of food microorganisms, but they do not integrate nucleic acid extraction components, the degree of automation is low, and the equipment is cumbersome, so they are only suitable for laboratory testing.

Contents of the invention

The present invention aims to at least solve the technical problems existing in the prior art, and particularly innovatively proposes a portable rapid detection method for pathogenic bacteria.

In order to achieve the above object of the present invention, the present invention provides a portable rapid detection system for pathogenic bacteria, the key of which is to include: power supply unit, first control chip, second control chip, constant temperature control unit, laser detection unit, nucleic acid extraction unit, human-computer interaction module, communication module,

The power output end of the power supply unit is connected to the power input end of the nucleic acid extraction unit, the power output end of the power supply unit is also connected to the power input end of the first control chip, and the constant temperature signal transmission end of the first control chip is connected to the signal transmission end of the constant temperature control unit, The signal transmission end of the laser detection unit is connected to the laser signal transmission end of the first control chip, the power input end of the constant temperature control unit and the laser detection unit is connected to the power output end of the power supply unit, and the signal output end of the first control chip is connected through a serial port communication The signal input terminal of the second control chip, the signal output terminal of the second control chip is connected to the signal input terminal of the human-computer interaction module, the power supply unit is respectively connected to the power input terminal of the second control chip and the power input terminal of the human-computer interaction module, and the communication module The data transmission end is connected to the upper computer data receiving end, and the communication module control chip data transmission end is connected to the first control chip and the second control chip data transmission end.

The beneficial effect of the above solution is: the analysis and judgment of nucleic acid can be realized through the above control circuit, the detection result can be quickly detected, and the data can be displayed in real time.

The invention also discloses a portable rapid detection device for pathogenic bacteria, the key of which is to include: a nucleic acid extraction module, a heating tank 1, a heating plate 2, a control circuit board 3, a laser sensor fixing seat 5, a laser sensor 14, and a laser emitter 6. The lower fixing seat 7 of the laser transmitter, the hole for placing the substance to be tested 22, the fixing piece for the substance to be tested 23, the laser through hole 24,

The laser emitter 6 is fixed on the lower fixing seat 7 of the laser emitter, the laser sensor 14 is fixed on the laser sensor fixing seat 5, the laser emitter 6, the heating tank 1 and the laser sensor 14 are placed in parallel in sequence, and the heating tank 1 facade is provided with a laser Through the hole 24, the laser light emitted by the laser emitter 6 passes through the laser through hole 24 and reaches the laser sensor 14,

The top surface of the heating tank 1 is covered with a fixed piece 23 of the substance to be measured, a hole 22 for placing the substance to be tested is opened on the fixed piece 23 for the substance to be tested, and a groove is arranged in the heating tank 1 below the hole 22 for placing the substance to be tested. The substance to be measured, when the laser is emitted, passes through the substance to be measured in the groove;

The heating sheet 2 is placed between the heating tank 1 and the heating tank fixing seat 13;

The nucleic acid extraction module is inserted into a test tube containing the substance to be extracted to extract the nucleic acid of the substance to be tested.

The beneficial effect of the above technical solution is: by installing the detection device in the detection system, combined with the detection structure of the detection system, the substance to be detected can be effectively detected.

The portable rapid detection device for pathogenic bacteria is effective. The nucleic acid extraction module includes: a handle 16, an elastic fixing clip 17, a contact rod 19, a magnetic area 20, and a sleeve 18,

The lower end of the handle 16 is equipped with a fixing plate, and the lower end of the fixing plate is provided with an elastic fixing clip 17, and the elastic fixing clip 17 is used to fix the sleeve 18, and the contact rod 19 is fixed on the fixing hole of the fixing plate, and the fixing hole of the fixing hole The internal thread cooperates with the external thread of the contact rod 19, and the contact rod 19 is fixed on the fixed plate. The bottom end of the contact rod 19 is magnetized to generate a magnetic force zone 20, and the magnetic force zone 20 is used to probe into the concave of the heating tank 1. The magnetic beads are adsorbed in the groove, and the two sides of the handle 16 are connected with the fixing plate by connecting posts 21 .

The beneficial effects of the above technical solution are: the nucleic acid extraction module has a reasonable structural design and is easy to carry.

The portable rapid detection device for pathogenic bacteria, preferably, also includes: a fixed seat 15 on the laser transmitter,

The upper fixing seat 15 of the laser emitter is a clamping part formed by inversion, and the upper fixing seat 15 of the laser emitter clamps the laser emitter 6 in the middle, and the laser emitter formed by the inversion is fixed on the laser emitter by piercing nails. The seat 15 is fixed, and the nails pass through the upper fixing seat 15 of the laser emitter and are nailed into the lower fixing seat 7 of the laser emitter.

The beneficial effect of the above technical solution is that: the fixing seat on the laser emitter presses and fixes the laser emitter, so that the laser emission is stable without deviation.

The portable rapid detection device for pathogenic bacteria, preferably, also includes: a heat insulation board 12, which is wrapped around the heating tank 1 and the heating tank fixing seat 13, and the heat insulation board 12 is connected with the laser Light-transmitting holes are provided on the opposite side elevations of the via hole 24 .

The beneficial effects of the above technical solution are: the heat shield can prevent the user from being burned, and keep the temperature of the substance to be tested in the heating bath constant.

The portable rapid detection device for pathogenic bacteria preferably further includes: a display module 9 installed on the control circuit board 3 for displaying data.

Preferably, the portable rapid detection device for pathogenic bacteria further includes: a fine-tuning knob 10 , which is arranged around the lower part of the laser sensor fixing seat 5 for adjusting the height of the laser sensor 14 .

In the portable rapid detection device for pathogenic bacteria, preferably, the control circuit board 3 includes: a first control chip, a second control chip, a constant temperature control unit, a laser detection unit, a power supply,

The signal transmission end of the first control chip is connected to the signal transmission end of the second control chip, the constant temperature signal transmission end of the first control chip is connected to the signal transmission end of the constant temperature control unit, and the signal transmission end of the laser detection unit is connected to the first control chip laser The detection signal terminal, the power supply is connected to the power input terminals of the first control chip, the second control chip, the display module, the constant temperature control unit, and the laser detection unit.

In the portable rapid detection device for pathogenic bacteria, preferably, the constant temperature control unit includes: a temperature sensor, a heater and a MOS tube,

One end of the heater is connected to the drain of the MOS tube, the other end of the heater is connected to the positive pole of the power supply, the negative pole of the power supply is connected to the source of the MOS tube, the gate of the MOS tube is connected to the PWM pulse modulation terminal of the first control chip, and the temperature The sensor temperature signal input end is connected to the heater temperature signal output end, and the temperature sensor temperature signal output end is connected to the first control chip temperature signal input end.

The beneficial effect of the above technical solution is that the constant temperature of the substance to be measured in the heating bath is guaranteed by the constant temperature control unit, and the effect is remarkable.

The invention also discloses a detection method for a portable rapid detection device for pathogenic bacteria, the key of which is to include:

Step 1, add magnetic beads to the substance to be tested, put the substance to be tested into the heating tank for constant temperature heating through the constant temperature control unit, put the nucleic acid extraction module into the substance to be tested, and absorb nucleic acid according to the magnetic force area of the nucleic acid extraction module The magnetic beads are sucked out;

Step 2: Heat the substance to be tested through the heater, and the heating control method is as follows:

Taking the temperature difference between the real-time temperature of the ceramic heater and the set value and the temperature difference change rate as the input of the fuzzy controller, the values of ΔK _P , ΔK _I and ΔK _D are obtained through the fuzzy controller, and then according to the self-tuning formula

K _P ＝K _P0 +ΔK _P

K _I =K _I0 +ΔK _I

K _D ＝K _D0 +ΔK _D

Calculate the value of the adjusted proportional coefficient K _P , integral coefficient K _I , and differential coefficient K _D , where ΔK _P represents the change of the proportional coefficient, ΔK _I represents the change of the proportional coefficient; ΔK _D represents the change of the integral coefficient K _P0 represents the initial value of the integral coefficient; K _I0 represents the initial value of the differential coefficient, and K _D0 represents the initial value of the differential coefficient; then input the adjusted values of K _P , K _I and K _D into the PID controller, and the PID The differential equation of the controller is

Then the transfer function of the PID controller includes, e _t is the temperature difference between the real-time temperature of the ceramic heater and the set value, d _t is the differential of time, It is the differential of the temperature difference between the real-time temperature of the ceramic heater and the set value;

Among them, K _P is the proportional coefficient; T _I is the integral time constant; T _D is the differential time constant; D (S) is the duty cycle; E (S) is the deviation; U (S) is the output;

In the constant temperature control unit, e(k) and e _c (k) represent the temperature difference and temperature difference change rate between the set value and the actual value, and the actual output value u(t) is the duty cycle of the MOS tube. By controlling the duty cycle The air ratio controls the controlled object;

Step 3: The laser emitter emits laser light, and the laser light passes through the laser hole to irradiate the substance to be tested. The laser sensor receives the laser light passing through the laser hole, and after analyzing it through the control circuit board, it displays the object to be tested on the display module. The test data of the test substance.

In summary, owing to adopting above-mentioned technical scheme, the beneficial effect of the present invention is:

The present invention is a portable rapid detection device for food-borne pathogenic bacteria. The portable rapid detection device for food-borne pathogenic bacteria is a combination of biotechnology and automation technology. It adopts a relatively advanced detection method in the world - laser detection. The negative or positive of the sample is judged by detecting the turbidity of the solution. Its hardware structure is relatively simple, and the software is also written in C language with high portability. The device can detect four groups of samples at the same time at a time, which improves the detection efficiency. The detection device solves the needs of outdoor detection. By comparing with similar products on the market, the detection device invented in this paper has the following characteristics:

portability

The size of the whole detection device is 255mm*150mm*53mm. Compared with similar foreign detection devices, it is smaller in size and easy to carry. Foreign detection devices must provide 220V AC power supply, and most of them are heavy, which limits their It can be used in the laboratory, but cannot complete the outdoor detection work. The power supply used in the present invention is a 5V DC power supply, and a lithium battery can meet its working requirements, and its weight is about 5kg, which enables it to successfully complete outdoor detection work.

economy

Comparing this device with the same type of foreign devices from an economic point of view, we can clearly draw its superiority. Among the products of the same type, DuPont’s The price of Q7 in China is as high as 400,000 yuan, and the cost of the device of the present invention is less than one-tenth of it, and the maintenance of foreign devices is also quite troublesome. Long, the invention uses domestic technology, and after-sales maintenance is relatively convenient.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is a schematic diagram of the portable pathogen rapid detection system of the present invention;

Fig. 2 is a perspective view of the portable pathogenic bacteria rapid detection system of the present invention;

Fig. 3 is the schematic diagram of the nucleic acid extraction module of the portable pathogen rapid detection system of the present invention;

Fig. 4 is a schematic diagram of a portable pathogenic bacteria rapid detection device of the present invention;

Fig. 5 is the driving circuit diagram of the constant temperature control unit of the portable pathogenic bacteria rapid detection device of the present invention;

Fig. 6 is a flow chart of the portable pathogenic bacteria rapid detection device of the present invention;

Fig. 7 is the circuit diagram of the laser emitter of the portable pathogenic bacteria rapid detection device of the present invention;

Fig. 8 is a circuit diagram of the laser sensor of the portable pathogenic bacteria rapid detection device of the present invention;

Fig. 9 is a flow chart of the portable pathogen rapid detection method of the present invention;

Fig. 10 is the experimental data diagram of the portable pathogenic bacteria rapid detection method of the present invention;

Fig. 11 is the experimental data diagram of the portable pathogenic bacteria rapid detection method of the present invention;

Fig. 12 is a schematic diagram of the communication module of the portable pathogen rapid detection device of the present invention;

Fig. 13 is a schematic diagram of the communication module of the portable pathogen rapid detection device of the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention.

In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be mechanical connection or electrical connection, or two The internal communication of each element may be directly connected or indirectly connected through an intermediary. Those skilled in the art can understand the specific meanings of the above terms according to specific situations.

The portable rapid detection device for food-borne pathogens takes food-borne pathogens as the detection object, detects the change of turbidity of the sample solution in real time through the laser sensor, and transmits the detection signal to the control chip 1, and the control chip 1 undergoes calculation processing Finally, the data is transmitted to the control chip 2, and the control chip 2 displays the result on the human-computer interaction module. The working principle of the system is shown in Figure 1;

In the figure: 1. Heating tank, 2. Ceramic heating sheet, 3. Control circuit board, 4. Battery, 5. Laser sensor holder, 6. Laser emitter, 7. Laser emitter holder, 8. Fan, 9 , display, 10, fine-tuning knob, 11, radiator, 12, heat shield, 13, heater base, 14, laser sensor, 15, laser transmitter fixing seat,

The laser transmitter 6 is fixed on the lower fixing base 7 of the laser transmitter, the laser sensor 14 is fixed on the laser sensor fixing base 5, the laser transmitter 6, the heating tank 1 and the laser sensor 14 are placed in parallel in turn, and the laser transmitter 6 passes through the fixing bolt It is fixed on the lower fixing seat 7 of the laser emitter, the first extension end of the control circuit board 3 is connected to the side edge of the lower fixing seat 7 of the laser emitter, the heating tank 1 is placed in parallel with the laser transmitter, and a laser pass is arranged on the facade of the heating tank 1 Holes 24, the laser through hole 24 is used for the laser emitter 6 to emit laser light through the laser through hole 24 to reach the laser sensor 14, the second extended end of the control circuit board 3 is connected to the side edge of the heating tank base 13, the laser sensor 14 is placed parallel to the heating tank 1, the laser sensor 14 is fixed on the laser sensor holder 5, the third extension end of the control circuit board 3 is connected to the side edge of the laser sensor holder 5, and the laser emitter 6 emitting end is connected to the heating tank 1 The laser via hole 24 on the facade is on the same line as the laser sensor 14, and the laser light emitted by the laser emitter 6 passes through the laser via hole 24 and reaches the laser sensor 14.

As shown in Figure 4, the present invention provides a portable rapid detection system for pathogenic bacteria, the key of which is to include: a power supply unit, a first control chip, a second control chip, a constant temperature control unit, a laser detection unit, and a nucleic acid extraction unit , human-computer interaction module,

The power output end of the power supply unit is connected to the power input end of the nucleic acid extraction unit, the power output end of the power supply unit is also connected to the power input end of the first control chip, and the constant temperature signal transmission end of the first control chip is connected to the signal transmission end of the constant temperature control unit, The signal transmission end of the laser detection unit is connected to the laser signal transmission end of the first control chip, the power input end of the constant temperature control unit and the laser detection unit is connected to the power output end of the power supply unit, and the signal output end of the first control chip is connected through a serial port communication The signal input terminal of the second control chip, the signal output terminal of the second control chip is connected to the signal input terminal of the human-computer interaction module, and the power supply unit is respectively connected to the power input terminal of the second control chip and the power input terminal of the human-computer interaction module.

The beneficial effect of the above solution is: the analysis and judgment of nucleic acid can be realized through the above control circuit, the detection result can be quickly detected, and the data can be displayed in real time.

The human-computer interaction module includes:

① Interface design of touch screen

The portable foodborne pathogen detection system is a detection system with touch screen mode. In addition to the display function, the touch screen must also have a touch function. All the instructions of the whole detection process can be realized by touch, including system initialization, parameter setting, start-up operation, image processing and other functions. Through comparative analysis, a 3.5-inch LCD touch screen with a resolution of 480*320 produced by Defeilai Company was finally selected as the display of the entire device.

②Design of key module

According to different connection methods, it can be divided into matrix keyboard and non-matrix keyboard. Matrix keyboards and non-matrix keyboards have different advantages and disadvantages. For matrix keyboards, it occupies less system I/O interface resources and can effectively save system I/O resources. It is suitable for relatively tight I/O interfaces. In the control circuit; the non-matrix keyboard occupies more I/O interface resources, but it is easy to use and easy to program, and is suitable for control circuits with relatively loose I/O interfaces. For example, designing a 3*3 matrix keyboard only needs to occupy 6 I/O interfaces, but designing a non-matrix keyboard that also contains 9 keys requires occupying 9 I/O interfaces. The controller used in the portable foodborne pathogen detection system designed in this project is a 64-pin dsPIC33FJ64GS606 control chip, and the I/O interface is relatively generous, so this design uses a non-matrix keyboard.

According to the actual requirements of the portable foodborne pathogen detection system, the non-matrix keyboard is designed with 8 keys, two of which are used to restart controller 1 and controller 2, and one key is used for the constant temperature system One button is used to set other parameters of the experiment, one button is used to start and run the experiment, and the remaining three buttons are used as digital input buttons.

③Design of SD card function module

In the design, a structural diagram of helical DNA is used as the boot background interface of the entire detection system, but since the memory RAM of the controller itself is only 64KB, it cannot accommodate this DNA with a resolution of 480*320 and a size of 300K The double helix structure diagram requires the use of an external memory. This design adds the SD card function, using a 2GB SD card as the memory of the helical DNA structure diagram. SD card has two working modes, SD mode and SPI mode.

As shown in Figures 1 and 2, the present invention also discloses a portable rapid detection device for pathogenic bacteria, the key of which is to include: a nucleic acid extraction module, a heating tank 1, a heating plate 2, a control circuit board 3, and a laser sensor fixing seat 5 , a laser sensor 14, a laser emitter 6, a lower fixing seat 7 for the laser emitter, a placement hole 22 for the substance to be measured, a fixing sheet 23 for the substance to be measured, and a laser through hole 24,

The laser emitter 6 is fixed on the lower fixing seat 7 of the laser emitter, the laser sensor 14 is fixed on the laser sensor fixing seat 5, the laser emitter 6, the heating tank 1 and the laser sensor 14 are placed in parallel in sequence, and the heating tank 1 facade is provided with a laser Through the hole 24, the laser light emitted by the laser emitter 6 passes through the laser through hole 24 and reaches the laser sensor 14,

The top surface of the heating tank 1 is covered with a fixed piece 23 of the substance to be measured, a hole 22 for placing the substance to be tested is opened on the fixed piece 23 for the substance to be tested, and a groove is arranged in the heating tank 1 below the hole 22 for placing the substance to be tested. The substance to be measured, when the laser is emitted, passes through the substance to be measured in the groove;

The heating sheet 2 is placed between the heating tank 1 and the heating tank fixing seat 13;

The nucleic acid extraction module is inserted into a test tube containing the substance to be extracted to extract the nucleic acid of the substance to be tested.

The beneficial effect of the above technical solution is: by installing the detection device in the detection system, combined with the detection structure of the detection system, the substance to be detected can be effectively detected.

As shown in Figure 3, the portable pathogenic bacteria rapid detection device is effective, and the nucleic acid extraction module includes: handle 16, elastic fixing clip 17, contact rod 19, magnetic area 20, pipe cover 18,

The lower end of the handle 16 is equipped with a fixing plate, and the lower end of the fixing plate is provided with an elastic fixing clip 17, and the elastic fixing clip 17 is used to fix the sleeve 18, and the contact rod 19 is fixed on the fixing hole of the fixing plate, and the fixing hole of the fixing hole The internal thread cooperates with the external thread of the contact rod 19, and the contact rod 19 is fixed on the fixed plate. The bottom end of the contact rod 19 is magnetized to generate a magnetic force zone 20, and the magnetic force zone 20 is used to probe into the concave of the heating tank 1. The magnetic beads are adsorbed in the groove, and the two sides of the handle 16 are connected with the fixing plate by connecting posts 21 .

The beneficial effects of the above technical solution are: the nucleic acid extraction module has a reasonable structural design and is easy to carry.

Nucleic acid extraction module

The nucleic acid extraction module is the first to be executed during the entire detection process. It is a pre-processing module, and the success of nucleic acid extraction directly affects the final detection result. The accounting extraction module mainly uses magnetic field to adsorb nucleic acid, so as to achieve the purpose of extraction.

Before the detection starts, put a certain amount of magnetic beads into the sample to be extracted, and then put the sample into the constant temperature module for heating. The constant temperature is set at about 80 degrees, and then put the nucleic acid extraction device shown in Figure 3 Into the sample to be extracted, and make it move up and down, destroy the biological structure of the cell, release the DNA, the magnetic beads will combine with the DNA, under the action of the magnetic field, the magnetic bar on the nucleic acid extraction device will suck the magnetic beads away, so that Reached the purpose of extracting nucleic acid.

The portable rapid detection device for pathogenic bacteria, preferably, also includes: a fixed seat 15 on the laser transmitter,

The upper fixing seat 15 of the laser emitter is a clamping part formed by inversion, and the upper fixing seat 15 of the laser emitter clamps the laser emitter 6 in the middle, and the laser emitter formed by the inversion is fixed on the laser emitter by piercing nails. The seat 15 is fixed, and the nails pass through the upper fixing seat 15 of the laser emitter and are nailed into the lower fixing seat 7 of the laser emitter.

The beneficial effect of the above technical solution is that: the fixing seat on the laser emitter presses and fixes the laser emitter, so that the laser emission is stable without deviation.

The portable rapid detection device for pathogenic bacteria, preferably, also includes: a heat insulation board 12, which is wrapped around the heating tank 1 and the heating tank fixing seat 13, and the heat insulation board 12 is connected with the laser Light-transmitting holes are provided on the opposite side elevations of the via hole 24 .

The beneficial effects of the above technical solution are: the heat shield can prevent the user from being burned, and keep the temperature of the substance to be tested in the heating bath constant.

The portable rapid detection device for pathogenic bacteria preferably further includes: a display module 9 installed on the control circuit board 3 for displaying data.

Preferably, the portable rapid detection device for pathogenic bacteria further includes: a fine-tuning knob 10 , which is arranged around the lower part of the laser sensor fixing seat 5 for adjusting the height of the laser sensor 14 .

In the portable rapid detection device for pathogenic bacteria, preferably, the control circuit board 3 includes: a first control chip, a second control chip, a constant temperature control unit, a laser detection unit, a power supply,

The signal transmission end of the first control chip is connected to the signal transmission end of the second control chip, the constant temperature signal transmission end of the first control chip is connected to the signal transmission end of the constant temperature control unit, and the signal transmission end of the laser detection unit is connected to the first control chip laser The detection signal terminal, the power supply is connected to the power input terminals of the first control chip, the second control chip, the display module, the constant temperature control unit, and the laser detection unit.

In the portable rapid detection device for pathogenic bacteria, preferably, the constant temperature control unit includes: a temperature sensor, a heater and a MOS tube,

One end of the heater is connected to the drain of the MOS tube, the other end of the heater is connected to the positive pole of the power supply, the negative pole of the power supply is connected to the source of the MOS tube, the gate of the MOS tube is connected to the PWM pulse modulation terminal of the first control chip, and the temperature The sensor temperature signal input end is connected to the heater temperature signal output end, and the temperature sensor temperature signal output end is connected to the first control chip temperature signal input end.

The beneficial effect of the above technical solution is that the constant temperature of the substance to be measured in the heating bath is guaranteed by the constant temperature control unit, and the effect is remarkable.

Thermostatic Control Module

The constant temperature control module is a very important part of the device. Foodborne pathogenic bacteria need a suitable ambient temperature during the rapid value-added process, so it is necessary to design a constant temperature module to meet this demand. The main circuit schematic diagram of the constant temperature module is shown in Figure 5:

The controller uses dsPIC33FJ64GS606 from the Microchip series, which has an independent PWM generator and 10-bit A/D sampler inside, which avoids external A/D chips and simplifies the entire circuit structure; the heater uses a 5V ceramic heating chip , The heating tank is made of aluminum block, and the temperature sensor is DS18B20 from Dallas Semiconductor Company. The constant temperature setting value of the constant temperature module is generally above 60 degrees. In order to avoid the module having a great impact on other modules, a heat shield is added around the constant temperature module, which can reduce the impact on other modules. It can also improve the performance of the constant temperature module. According to the parameter characteristics of the circuit, the driving circuit of MOSFET is selected as follows:

Dual-channel optocoupler isolation HCPL_2631 is used for the isolation chip, and dual-channel MAX17600 is selected for the driver chip. Since the entire detection device is designed as a four-channel sampling, multiple drive circuits are required. The use of dual-channel isolation and driver chips is beneficial to simplify the circuit.

As shown in Figure 6, the controller controls the output power of the ceramic heating chip through the duty cycle of the MOSFET, so as to achieve the purpose of temperature control. The larger the duty cycle, the greater the output power of the ceramic heater. When heating with a certain duty cycle, the temperature sensor will transmit the temperature of the heating tank to the controller in real time, and the controller will change the value of the duty cycle after calculation and judgment. , by constantly correcting the duty cycle, changing the output power of the heating chip, and then keeping the temperature of the heating tank constant. Commonly used control methods include PID control, sliding mode control, stick control, etc. The method used in this device is fuzzy PID control. The fuzzy PID controller does not depend on the mathematical model of the controlled object, and is suitable for the controlled object of this device. , and the fuzzy PID controller is easier to implement.

Laser detection technology is one of the most advanced technologies in the contemporary era and has been used in more and more fields. Compared with traditional chemical detection methods, it has higher detection accuracy and is more convenient to use. This device uses laser detection, and the detection result can be inferred by the change of the turbidity of the solution detected by the laser. In order to improve the working efficiency of detection, this device is designed with the function of four-way simultaneous detection, which is composed of four-way laser emission circuits and four-way laser detection circuits. The circuit diagram of each laser emission circuit is shown in Figure 7:

When the laser emitter works for a long time, the temperature of the laser emitter will increase obviously, which will lead to the decrease of the output power of the laser emitter, which will cause a large deviation in the detection results. In order to solve this problem, a temperature control is designed. The system is used to ensure that the temperature of the laser transmitter is stable within a certain range. Fix the laser transmitter on the metal base, and the metal base is placed above the cooling plate. The working mode of the cooling plate is controlled by the external control circuit. When the temperature of the laser transmitter is too high, the cooling plate starts to work, and the emission The temperature of the laser transmitter is lowered. When the temperature of the transmitter is lower than the set value, the cooling plate stops working. In this way, the temperature of the laser transmitter is stabilized within a certain range, thereby improving the accuracy of the detection results.

When the laser light emitted by the laser transmitter passes through the sample solution and shines on the laser receiver, the laser receiver converts the optical signal into an electrical signal. The stronger the light intensity of the received laser, the greater the photocurrent generated, and then through Resistor RL converts photoelectric current into voltage, and uses A/D sampler to measure the sampling voltage. If the turbidity of the solution changes, the light intensity passing through the solution will change accordingly, the photocurrent generated by the receiver will also change, and the sampling voltage will also change, so the detection result can be judged by using the change in voltage. R1 and C1 form a filter circuit, and the power supply uses a 3.3V DC power supply, as shown in Figure 8. The laser sensor uses FDS100, and the A/D sampler uses the 10-bit A/D module that comes with the controller. The sampling time can be adjusted according to the working time of the whole detection device.

Through theoretical analysis, it can be known that when the sample to be tested is negative, it does not contain food-borne pathogenic bacteria. The detection process basically remains unchanged, so the obtained sampling voltage value also remains basically unchanged throughout the detection process, so the obtained sampling curve is basically a parallel straight line, which is lower than the threshold line. The threshold line is a standard guideline derived by experts in the biological field for judging whether the sample is negative or positive. When the sampling curve has a sampling value higher than this line, it means that the tested sample is positive. When the sampling curve When consistently below this curve, the sample being tested is negative.

Since the constant temperature control module, nucleic acid extraction module and laser detection module are all in the same device, the working temperature of each component should be fully considered to dissipate heat for it. The temperature of the constant temperature module is generally higher than 60°C, while the nucleic acid extraction module works at a higher temperature, even exceeding 80°C. The high temperature of these two modules will affect other modules, especially for the temperature stability of the laser transmitter. If the laser transmitter cannot work stably, the detection circuit will inevitably change with the power of the transmitter, which will have a great impact on the accuracy of detection. Add four heat shields around the constant temperature module and the nucleic acid extraction module to slow down the heat exchange with other modules, and place a larger aluminum radiator at the lower end of the laser transmitter, next to the radiator Install 4-way fans to enhance air circulation and heat dissipation.

The realization of portable devices is inseparable from the support of human-computer interaction software technology. The software should meet the requirements of functional integrity, practicality, ease of operation and aesthetics. The software system adopts the design idea of modularization and integration. Among them, the instrument parameter setting module is used to set the working time of the detection device, the constant temperature value of the constant temperature module, and the working status of the four-way laser detection on/off; the A/D sampling module is used to sample the detection results. And transmit the result to the controller; the PID control module is used for constant temperature adjustment to stabilize the temperature at the set value; the serial port communication is used for data transmission between the two controllers. If the data of controller 1 is to be displayed on the display, The data must be transmitted to the controller 2 first, and the data to be displayed is displayed on the human-computer interaction module through the controller 2; the detection result display module is used to display the detected experimental data and temperature values.

communication module

The communication module of the portable food-borne pathogen detection system is mainly divided into two parts. The first part is the communication between the portable food-borne pathogen detection system and the upper computer; the second part is the communication between the two main control chips. mutual communication, the structure of the communication module is shown in Figure 12;

The communication module mainly includes two parts: the communication module between the portable foodborne pathogen detection system and the host computer and the communication module between the controllers, and each part includes two parts: hardware design and software design.

There are many types of communication. In order to facilitate the connection, we use a USB interface and convert the USB communication into serial communication through the chip CH340, which avoids the use of complicated USB communication protocols. The specific circuit diagram is shown in Figure 13.

control algorithm

As shown in Figure 9, when designing the constant temperature module, it is necessary to apply a control method to the control object. After considering the performance parameters of the constant temperature module, fuzzy PID control is selected, because the mathematical model of the controlled object of this device is uncertain. , and can meet the various performance indicators of the constant temperature module, and the fuzzy PID is easy to implement.

Proportional-integral controller is the most widely used controller at present, and it is mostly used in liquid level, pressure, flow and other control systems in industrial production. Since the introduction of integral action can eliminate residual error, it makes up for the defects of pure proportional control and obtains better control quality. However, the introduction of integral action will make the system stability worse. For control systems with large inertia hysteresis, it should be avoided as much as possible.

There are two fuzzy self-tuning PID controllers in the present invention, one of which is the constant temperature system of the laser transmitter, and the other is the constant temperature system of the heating tank. The actuators of the two constant temperature systems are the same, which is the duty cycle of the MOSFET; The objects are different. The controlled object of the laser transmitter constant temperature system is a cooling plate, and the controlled object of the heating tank constant temperature system is a ceramic heating plate.

The controlled object in the constant temperature system is a ceramic heating plate or a cooling plate, therefore, the input of the fuzzy PID controller of the constant temperature system is the deviation between the real-time temperature of the ceramic heating plate or the real-time temperature of the cooling plate and the corresponding set temperature The value e ₁ (k) and the variation e _c (k) of the deviation, the output is the three parameters of the PID controller, namely ΔK _P , ΔK _I and ΔK _D .

Set the fuzzy sets of e ₁ , e _c , ΔK _P , ΔK _I and ΔK _D as: {NB, NM, NS, ZE, PS, PM, PB}, where NB, NM, NS, ZE, PS, PM, PB represent negative big, negative middle, negative small, zero, positive small, positive middle, positive big respectively; fuzzy set domains are {-3, -2, -1, 0, 1, 2, 3}.

The actual value ranges of input quantities e ₁ , e _c and output quantities ΔK _P , ΔK _I and ΔK _D are the basic discourse domain of the system. Quantities in the basic domain of discourse are analog quantities that take continuous values. Let the basic discourse domain of deviation e ₁ be [-x, x], if the fuzzy set discourse domain of deviation e ₁ is {-n, -(n-1),..., n-1, n}, then define the precise quantity The fuzzy quantization factor of _{e 1} is Ke as:

In the same way, the quantitative factor of the deviation variation e _c can be defined

2) Determination of membership function

Commonly used membership functions are triangular, trapezoidal and Gaussian membership functions. Since the triangular membership function is the simplest, this paper selects the triangular function as the membership function of the deviation and deviation variation, as shown in Figure 10, and selects the triangular function as the membership function of the three parameter corrections of the PID controller, as shown in Figure 11.

Controller rule settings

Considering the effects of the three control parameters K _P , K _I , and K _D of the PID controller comprehensively from the aspects of system stability, response speed, overshoot and steady-state accuracy, the fuzzy control rules can be drawn as follows:

First, in PID control, the response speed of the system is determined by _KP . In order to make the system achieve good performance, when it is in the early stage of adjustment, a larger value of K _P should be selected appropriately to improve the system response speed _; The response speed has a small overshoot at the same time; at the end of the adjustment, K _P should choose a larger value in order to reduce the steady-state error of the system and improve the control accuracy.

Second, the integral action can eliminate the steady-state error of the system. When it is in the early stage of adjustment, because of some factors such as saturation nonlinearity, the phenomenon of integral saturation may occur, resulting in a large overshoot. Therefore, in order to avoid integral saturation, the role of the integral link should be _weakened at the initial stage of adjustment, and K _I can even be zero; At the end, it is necessary to appropriately increase the integral action to reduce the system steady-state error and improve the control accuracy.

Third, the differential link can predict the trend of error changes, and make the control effect of suppressing errors equal to zero or even a negative value in advance, thereby avoiding serious overshooting of the controlled variable and improving the dynamic characteristics of the system during the adjustment process. According to actual experience and combined with theoretical analysis, in the initial stage of adjustment, the differential action should be increased, that is, a larger K _D value should be taken to make the overshoot smaller or even no overshoot; in the middle stage of adjustment, K _D should be selected with an appropriate size The value of ; at the end of the adjustment, the value of K _D should be reduced in order to weaken the braking effect of the controlled process.

From the above analysis, the fuzzy control rules of ΔK _P , ΔK _I and ΔK _D according to the fuzzy statement of "IF A AND B THEN C" are shown in Table 1, Table 2 and Table 3 respectively.

Table 1 Fuzzy control rule table of ΔK _P

Table 2 Fuzzy control rule table of ΔK _I

Table 3 Fuzzy control rule table of ΔK _D

4) Defuzzification

The process of proposing precise output quantities from output fuzzy sets is called defuzzification, also known as clearing, defuzzification, and defuzzification. The commonly used methods for defuzzification of fuzzy quantities are maximum membership degree method, median method and center of gravity method. The center of gravity method includes and utilizes all the information of the fuzzy set, and focuses on different degrees of membership, so it has been widely used.

This paper applies the center of gravity method to achieve defuzzification, because the center of gravity method has a small change in the input signal, and the output value of its reasoning will also change. The center of gravity method is essentially the weighted average method, which can be expressed by the following formula:

Among them, u ^* is the exact quantity, x _i is the value of the corresponding element in the universe of the output quantity, Indicates the degree of membership of x _i .

After defuzzification, u ^* needs to be transformed into an accurate quantity u in the basic domain of discourse. Let the basic discourse domain of the output u be [-y, y], the fuzzy discourse domain be {-n, -(n-1),..., n-1, n}, define the proportional factor K=y/n, then Available

5) P, I, D self-tuning

After the output values of ΔK _P , ΔK _I and ΔK _D are obtained according to the fuzzy controller, the P, I, and D parameters are corrected by publicity 5.1, 5.2, and 5.3, and new values of P, I, and D parameters are obtained.

K _P ＝K _P0 +ΔK _P (5.1)

K _I =K _I0 +ΔK _I (5.2)

K _D ＝ K _D0 +ΔK _D (5.3)

The controller can only process digital signals, and it is necessary to discretize the PID control, then use P, I, D as the output value, and the duty cycle of the MOSFET as the output value, and control the output power of the cooling chip or ceramic heating through the value of the duty cycle The output power of the chip, and finally achieve the purpose of constant temperature.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (2)

1. A portable pathogenic bacteria rapid detection method is characterized by comprising the following steps:

step 1, adding magnetic beads into a substance to be detected, placing the substance to be detected into a heating tank, heating at constant temperature through a constant temperature control unit, placing a nucleic acid extraction module into the substance to be detected, and sucking out the magnetic beads adsorbing nucleic acids according to a magnetic area of the nucleic acid extraction module;

step 2, heating the substance to be detected by a heater, wherein the heating control method comprises the following steps:

in the fuzzy PID controller, the performance of the system is determined by fuzzy control and PID control together, the fuzzy control can set P, I, D parameter values, and the response speed of the system is determined by the integral action; the integral action eliminates the steady-state error of the system; the differential loop can predict the trend of error change in an energy-saving manner, and the control action of the suppression error is equal to zero or is a negative value in advance;

in a constant temperature system, a temperature difference e (k) and a temperature difference change rate e between a set value and an actual value are defined_c(k) The actual output value u (t) is the duty ratio of the MOS tube, and the ceramic heating sheet is controlled by controlling the duty ratio to achieve the purpose of heating the substance to be detected;

and 3, the laser emitter emits laser, the laser penetrates through the laser via hole to irradiate on the substance to be detected, the laser sensor receives the laser penetrating out of the laser via hole, and the detection data of the substance to be detected is displayed on the display module after the laser sensor is analyzed through the control circuit board.

2. The method for rapidly detecting a portable pathogen according to claim 1 wherein the step 2 comprises:

the temperature difference and the temperature difference change rate between the real-time temperature and the set value of the ceramic heating plate are used as input quantity of the fuzzy controller, and delta K is obtained through the fuzzy controller_P、ΔK_IAnd Δ K_DAccording to a self-tuning formula

K_P＝K_P0+ΔK_P

K_I＝K_I0+ΔK_I

K_D＝K_D0+ΔK_D

Calculating a proportional coefficient K after setting_PIntegral coefficient K_IValue of the differential coefficient K_DA value of (1), wherein Δ K_PRepresenting the variation of the proportionality coefficient, Δ K_IRepresenting the amount of change in the scaling factor; Δ K_DRepresenting the variation of the integral coefficient, K_P0An initial value representing an integral coefficient; k_I0Representing an initial quantity of differential coefficients, K_D0An initial value representing a differential coefficient; then K is put_P、K_IAnd K_DThe adjusted value is input into a PID controller, and the differential of the PID controllerThe equation is

<mrow> <mi>u</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <msub> <mi>K</mi> <mi>P</mi> </msub> <mo>&amp;lsqb;</mo> <msub> <mi>e</mi> <mi>t</mi> </msub> <mo>+</mo> <mfrac> <mn>1</mn> <msub> <mi>T</mi> <mi>I</mi> </msub> </mfrac> <munderover> <mo>&amp;Integral;</mo> <mn>0</mn> <mi>t</mi> </munderover> <msub> <mi>e</mi> <mi>t</mi> </msub> <msub> <mi>d</mi> <mi>t</mi> </msub> <mo>+</mo> <msub> <mi>T</mi> <mi>D</mi> </msub> <mfrac> <msub> <mi>d</mi> <msub> <mi>e</mi> <mi>t</mi> </msub> </msub> <msub> <mi>d</mi> <mi>t</mi> </msub> </mfrac> <mo>&amp;rsqb;</mo> </mrow>

The transfer function of the PID controller includes e_tIs the temperature difference between the real-time temperature and the set value of the ceramic heating plate, d_tIs a differential of the time, and is,the differential of the temperature difference between the real-time temperature and the set value of the ceramic heating plate is obtained;

wherein, K_PIs a proportionality coefficient; t is_IIs an integration time constant; t is_DIs a differential time constant; d (S) is duty cycle; e (S) is the deviation; u (S) is the output quantity;

in the thermostat control unit, e (k) and e_c(k) The temperature difference and the temperature difference change rate between the set value and the actual value are represented, the actual output value u (t) is the duty ratio of the MOS tube, and the controlled object is controlled by controlling the duty ratio.