Design Of Nucleic Acid Extraction Platform And Liquid Level Monitoring System Based On Microfluidic Chip

Although the traditional nucleic acid detection has a large detection flux,it has high requirements for environment,personnel and equipment,and takes a long time.COVID-19 has greatly exposed the short board of traditional nucleic acid detection.In 2020,the State Council will speed up the development of nucleic acid rapid detection equipment with short detection time,high sensitivity,simple operation and no need of laboratory.Nucleic acid POCT products are getting more and more attention.In this paper,based on microfluidic chip,a rapid nucleic acid extraction platform is built and a liquid level monitoring system is designed.The platform adopts magnetic beads method to extract nucleic acid,and the magnetic beads are quickly mixed with ultrasonic assistance.The stepping motor and pressure sensor cooperate to ensure that the ultrasonic probe can against the extraction chamber of the microfluidic chip with stable pressure.DC motor is used to drive the rotary valve of microfluidic chip with high torque,and Hall sensor is used to feedback angle to ensure accurate channel switching.The fluid in the microfluidic chip is driven by a plunger pump.The extraction platform’s control circuit is designed after finishing the mechanical structure design.Based on stm32 cubemx,keil5,QT and other software,a software system is developed to realize the whole process extraction action.The liquid level monitoring module is developed based on Open CV library for the condition that the extraction reagent is not pumped to the designated chamber due to chip leakage and plunger pump sealing problem in the extraction process.It can monitor the liquid level in microfluidic chip in real time,and warn the experimenter in case of abnormal condition.Finally,the extraction function of the extraction platform is tested through biological experiments,and the extraction efficiency of the extraction platform is verified.The results indicate that the extraction platform can ensure the stable efficiency of nucleic acid extraction,and successfully realize the extraction module development of the whole process nucleic acid detection machine.