Study On Key Technologies Of An Infectious Diseases Detection System Based On The Fully-Enclosed Cassette

In recent years,with the development of globalization and industrialization,many new infectious diseases emerge suddenly and become popular,threatening human's health.Timely and accurate diagnosis is the most primary part in prevention and treatment of infectious diseases.However,traditional methods for the diagnosis of infectious diseases have many defects,such as cumbersome steps,complicated operation and being unable to achieve automation.So,an infectious diseases detection system based on the fully-enclosed cassette has been developed at our research group,which can realize the detection step of sample in and answer out automatically in two hours using nucleic acid extraction based on magnetic separation and real-time PCR.In this paper,some key technologies of the system have been studied in detail for realizing the function of detection.1.An automatic miniature magnetic separation heating module with variable range is designed.In the module,in order to achieve the best magnetic separation effect,a magnetic separation model possessing a variable range is established and can automatically adjust the magnetic separation height according to the volume of reagents.In addition,a powervariable high-power aluminum-based resistance heating plate is designed for heating in nucleic acid extraction.2.A miniature fast dual-channel temperature control module is designed for nucleic acid extraction heating and PCR thermal cycle control.A high-performance temperature control unit,a high precision dual-channel temperature acquisition circuit and a high-power dualchannel temperature driver are integrated on an 8 cm×8 cm PCB.3.A high precision dual-channel fluorescence module that includes two high-brightness LEDs and two high-precision fluorescence signal acquisitions is designed.As for optical path,the filters and the dichroic mirrors are equipped to concentrate the four optical paths into a single lens.In the control part,a micro PCB plate which can be integrated inside the fluorescent module is designed to control the module to work.Cooperating with a scanning motor,the fluorescent module can realize the fluorescent detection function for three PCR tubes in real-time PCR.4.The S-type stepping motor control algorithm based on equal frequency dispersion is studied,which is used for controlling the five stepping motors in the detection system and improving the smoothness and stability of the operation.Based on the traditional PID control algorithm,the fuzzy control theory algorithm is integrated to develop the fuzzy adaptive PID temperature control algorithm that is applied to the nucleic acid extraction heating control and PCR thermal cycle control and achieves a perfect control effect.In the end,the reliability of the detection system is verified.Firstly,the performance of the hardware modules such as magnetic separation module,pipetting module,temperature control module and fluorescence module are verified.The results show that the hardware performance of the system meets the detection requirements.Finally,detections of clinical samples are processed in Jiangsu CDC and Zhejiang CDC,and the results were close to those by commercial instruments.