Research On Design Of Multichannel Plate PCR Instrument

With the rapid development of molecular biology,nucleic acid detection and amplification technology has attracted more and more attention during the COVID-19 pandemic in 2020.The flat-panel PCR instrument with strong functionality,low cost and small size has become a research hotspot in the global medical industry.In this paper,the design scheme of four channel flat plate PCR instrument is put forward by using biology,mechanical design,computer and other multidisciplinary technology.The temperature control system,PID control algorithm and software module are deeply studied and designed.In this paper,a four channel flat-panel PCR instrument based on chip is designed,which can run four different amplification programs at the same time.The main components of the device are: hardware circuit design,mechanical structure construction,software and algorithm design.RS232 and CAN communication mode are used to establish the device communication network.The collected data is transmitted to the main controller STM32F103 through CAN communication.The command and data are sent between the main controller and the touch screen through serial communication.The collected temperature information is transmitted to the display screen through RS232.The main contents of this paper are as follows.1)Hardware circuit design: mainly including the main control board and sub control board circuit design.The main control board mainly contains the minimum system circuit of STM32 main controller,CAN bus and communication circuit.The four sub control boards share the same circuit design,chiefly constituted with STM32 main control module,temperature acquisition module,communication module,driver module and power supply module.Using PT1000 temperature sensor,the semiconductor cooler 1MC06-126 which meets the requirements and has high cost performance is selected,and the circuit board is designed by calculating the performance parameters.2)Mechanical structure construction: using Solid Works software to design the appearance of the instrument and using 3D printer to make the instrument shell.The structure design of the temperature control module is mainly to heat insulate the four channels,so that there is no interference between them.According to the size of Peltier and heating plate,one channel is matched with two Peltier to fix the position of Peltier and temperature sensor,so that the temperature change can be transmitted to the main control module in time.3)Control algorithm design: using control algorithm based on the combination of fuzzy control and classical PID,using an improved tuning method to achieve the controller’s parameter self-tuning process,which can reduce the error values to the control range.Through the simulation experiment,it is found that it has great advantages in overshoot and response speed.4)Software design: the Visual TFT software development tool is used to draw the user interface,and C language is used to control the main control module,PID controller module and semiconductor driver.At the same time,the online programming function of upper computer is designed,mainly including the design of human-computer interaction module,storage parameters and communication protocol.The screen can display the curve of changes on temperature,the number of cycles and the experimental time in real time.The self-test and PCR amplification program of the device are realized through the joint debugging of software and hardware.5)Performance test: the temperature control accuracy,temperature rise and fall rates,accuracy,module uniformity and four channel uniformity of the device are tested by using thermometer and infrared imager,and the results show that they all meet the design requirements.The gene samples of epidermal growth factor receptor were used for amplification experiment,and the biological performance of the multi-channel plate PCR instrument was verified by analyzing the amplification results of samples,positive quality control and negative quality control.