Respiratory Disease Isothermal Nucleic Acid Detection System Based On Microfluidic Technology

Corona Virus Disease 2019(Covid-19),which has ravaged the world for nearly three years,poses a global threat to human health.In order to more quickly and accurately identify the Covid-19,an integrated intelligent detection system based on centrifuge microfluidic chips and colorimetric loop-mediated isothermal amplification(LAMP)has been presented in this paper.LAMP has the characteristics of high sensitivity,high specificity and rapid response.Microfluidic technology can realize the characteristics of miniaturization,automation and high throughput of the detection platform.Combined,they can maximize the speed and cost of detecting respiratory viruses.The centrifugal microfluidic detection system for nucleic acid detection is established in this paper.The system includes a centrifugal device driven by a highprecision stepping motor chip.Infrared heating temperature control device for temperature control;The optical detection system for absorbance detection is composed of photodiode and amplifying circuit.16Kb/s high-speed signal acquisition card signal acquisition system.All the control systems are controlled by C#,the whole system experiment process is automatic,the data is collected by the data acquisition card and transmitted to the upper computer for automatic analysis and processing,and display the test results.In order to meet the requirements of amplification technology and biochemical analysis,and realize automatic,rapid and accurate nucleic acid detection,this paper combined with microfluidic technology designed and developed a detection chip based on centrifugal microfluidic platform and a one-step sample tube suitable for chip.The sample tube is manufactured by 3D printing,and the micro-quantitative cavity is designed.The micro-samples can be released from the quantitative reagent tank by manually pressing the sample tube.Check valve design is used to prevent trace samples from backflow and control reagent evaporation.The chip adopts the combination of microchannel,capillary valve and siphon valve for fluid control,so as to realize the controlled orderly transportation,sampling,and detection of trace samples.Through theoretical calculation,the capillary valve and siphon valve on the chip are simulated and analyzed to optimize the chip detection system.Based on microfluidic chip and one-step sample tube,a miniaturized and automated nucleic acid detection system was developed to reduce the influence of monochromatic light on absorbance detection through the design of dual-optical path absorbance detection.The sensitivity,specificity and detection limit of COVID-19 were measured on the system,and it was found that the sample concentration and absorbance value showed a linear relationship.LDA and SVM clustering algorithms were used for real-time detection and analysis.The results showed that the sensitivity and specificity of the system were good,and the detection limit was 200copies/recation.The microfluidic isothermal nucleic acid detection platform and its supporting chip and sampling device designed above provide an intelligent,automatic and integrated technical solution for the on-site and real-time nucleic acid detection of respiratory diseases.