The Fabrication Of The Micro Droplet PCR Chip System

With the development of microfabrication technology(MEMS),micro total analysis system(μTAS)arises at the historic moment,making microfluidic technology become an important signal detection technology platform.As a sensitive nucleic acid testing tool,PCR is widely used from basic research to genetic diagnosis,multiple PCR combined with microfluidic technology is a hotspot of current research.This paper builds a micro droplet PCR chip system,using the micro droplet formation as an independent system,integrated with the dynamic continuous flow PCR system to reduce the groove on the adsorption of reactants.Micro-droplet PCR chip system consists of three parts,the microfluidic chip,driving system and the temperature control system.Microfluidic chip includes droplet formation structure and serpentine PCR reaction zone,drive system using the constant pressure microfluidic drive pump,temperature control platform consists of three zones,every temperature zone has PI film heater,heat conduction block,the temperature sensor.PCR reaction reagent was driven by constant pressure pump into micro droplet PCR chip,PCR mixture and mineral oil generated water-in-oil droplets,and then droplets flow through three constant temperature zone to complete DNA amplification.The simple temperature model of chip system was established using the conjugate heat transfer and fluid in the COMSOL.The temperature distribution field of micro droplet PCR chip system was studied and the design parameters of the system was optimized.The height of the heat conduction block should be less than 10 mm and the cover plate of chip should be 1 mm.In order to keep the temperature uniformity,the height of the channel should be less than 300 microns.The minimum gap between each zones is 3.5 mm under different environment.A high precision temperature control system was designed,including it’s hardware and software.The measure range of temperature is from 33 ℃ to 113 ℃,the precision is 0.08 ℃.The precision of temperature control is ±0.6 ℃in degeneration area,±0.4 ℃ in extension zone,±0.3 ℃ in annealing zone.The temperature uniformity meet the requirement of the temperature for PCR,and is suitable for the micro droplet PCR chip system.After integration of constant pressure microflow driven pump,chips and temperature control platform,the proportion of surfactant was optimized.In order to generate droplets there is a need to maintain pressure balance.Finally micro droplet was used to solve the problem of adsorption of PCR reactant to the surface.At last,the gene of escherichia coli was successfully amplificated,verifing the feasibility of the system.Based on this improved topic,integrated with the chip detection system,will become the development trend of future PCR,Which will promote the development of PCR reaction to achieve rapid genetic diagnosis.