Research On The PCR Instrument Based On Mixed Reagent Of Microfluidic Platform

PCR is a technique to amplify DNA in vitro,which can amplify a small amount of DNA in a short time to obtain a large number of specific fragments of DNA and facilitate the DNA detection and analysis.The PCR technique can be used in bacteria detection,food safety and disease diagnosis.At present,only a few research institutes are researching,and in terms of operation,they are all relying on manpower to complete and mix with centrifugal mixers,which is far from an automated process.To improve the automation,an automated microfluidic handling PCR instrument is developed and tested.The system includes a microfluidic module,an automatic control module and a PCR module.The microfluidic module has a high voltage DC circuit module and a microfluidic platform.The DC high voltage circuit is used to deliver a 200 V,the voltage applied to the electrode unit is controlled by the on-off of the MOS tube to realize the movement of the droplets.The microfluidic platformcontrols the droplet mixing based on the dielectric wetting effect(EWOD).The automatic control module is used for tample preparation.The main controller uses the pulse signal,and the number and frequency of the pulses determine the moving distance and speed of the motor..The temperature control of PCR module is critical.The PWM wave generated by the controller manipulates the power amplifying circuit which controls the semiconductor cooling components.The temperature control unit,realizes the precise heating or cooling functions by change the direction of the current through the the semiconductor cooling components.The voltage signal which represents the temperature variation was sent to the A/D module for digitization.The module of Bang-Bang control and PID control were used to adjust the duty ratio of the output PWM wave for the temperature control,C# language is used for the graphical user interface(GUI).The GUI was operated based on a four-layer model.The protocols were defined based on this four-layer model to complete the communication between the control unit and the driving circuit.The slave computer is used to complete the communication between the control unit and the driving circuit.The proposed system was designed,developed,and tested.PCR experiments were tested using the developed system and a commercial PCR system.The results showed that two methods were used to mix reagents and two instruments for amplification.The DDI2,DsRed,and Nrf1 D in the four experiments were designed to have little difference in brightness and no smearing.Therefore,the designed integrated PCR instrument can be used for PCR.The developed PCR system utilized the reagents prepared by the microfluidic platform realizes one-stop service for sample preparation and processing.The developed system is highly integrated,low-cost,reagent-efficent and less laborious.Which is a promising platform for educational institutions and point-of-care businesses.