Research Of The Subsystem On Nucleic Acid Extraction For Integrated Nucleic Acid Detection Workstation

With the rapid development of molecular biology technology in recent years,nucleic acid detection has become one of the commonly used research methods for pathogen microbial detection,species identification,species origin,diversity assessment.It plays a vital role in the fields of human clinical disease diagnosis,forensic identification,and environmental microorganisms testing and food safety testing.In view of the need for rapid detection of large-scale infectious diseases,this paper aims to develop a cost-effective,accurate,fast,multi-sample,multi-site nucleic acid detection workstation based on the summary of the development status and existing problems of advanced detection equipment at home and abroad.In order to achieve this goal,the overall design scheme of the nucleic acid detection workstation was proposed.According to the modular design principle,the workstation was divided into three modules: nucleic acid extraction subsystem,PCR amplification system and fluorescence detection system.This paper mainly completes the design of nucleic acid extraction subsystem module in nucleic acid detection workstation,and conducts in-depth research on the key technologies of micro-liquid treatment in the system.The main achievements and conclusions are as follows:According to the overall design scheme of the workstation,it is determined that the system adopts a multi-machine communication control scheme based on RS-485 bus.The software and hardware platform of the nucleic acid extraction subsystem is constructed: In terms of hardware,the main components selection,designing of circuit schematic and PCB diagram for the above modules are performed.According to the module function,design the main control board,DC motor driver board,stepper motor drive board,temperature control board,needle detection board and liquid level detection board,and complete the static and dynamic test of the board;In software,the PC software design of human-computer interaction interface,communication protocol formulation,communication port setting debugging module and debugging optimization module on parameter setting is completed.According to the modular design idea,the software design of the lower computer of the nucleic acid extraction main control module,the micro liquid processing module,the temperature control module,the needle detection module and the liquid level detection module.Aiming at the key technology of micro-liquid treatment,the liquid-dispensing pipetting method was adopted,and the pipe-type pipetting device was designed.By studying the needle-injection depth and pipetting speed control scheme,the hanging bead phenomenon of the pipetting process was solved.The requirements of low adhesion and high precision are avhieved in the pipetting process.In the aspect of system technical parameter verification,the prototype of the nucleic acid extraction subsystem has been set up.And through the software and hardware system debugging,the method of measuring gravity is used to determine the preciseness and accuracy of the pipetting device,and analyze the influence of liquid depth,pipetting speed and pipetting scheme on pipetting accuracy followed by parameter optimization and calibration of the pipetting device.Finally,it is completed to verify the pipetting preciseness and pipetting accuracy of the optimized solution through test.