Design of integrated droplet digital PCR gene chip

Abstract

In order to solve the problems of many defects in common digital PCR chips, an integrated droplet digital PCR chip was designed based on microfluidic, biology, optoelectronics, machinery and computer technology, which integrates droplet generation part, PCR amplification part and droplet fluorescence detection part. The droplet generation part used the flow focus micro structure to achieve droplet generation with two phase liquid, where the oil was used as continuous phase, the sample liquid as discrete phase. After the droplet generation process, the droplets were injected into collection chamber by the pressure of the pump. The amplification part uses the flat-plate PCR to achieve nucleic acid amplification in the integrated droplet digital PCR chip. After amplification, the integrated droplet digital PCR chip moves to detection location, under the irradiation of the excitation light the specificity target in the droplets will emit fluorescence, thus the fluorescence image is scanned by COMS camera and the result was analyzed by the software. The chips were made through injection molding process and the autofluorescence intensity of chip material was weak. Experimental results show that the coefficient of variation (CV) value of the droplet diameter was less than 2% and the temperature uniformity of the chip was less 0.5°C. That proves the chip designed has good droplet formation and thermal conductivity for nucleic acid amplification. The chip designed can reduce the manual operation error, operation difficulty and avoid the problems of droplet fusion, breakage and sample pollution in the process of pipetting.