Digital Droplet Polymerase Chain Reaction Device Using a Microfluidic Chip

Research on DNA is particularly important in the diagnosis, control, and treatment of many diseases, including cancer. Today, the use of digital droplet polymerase chain reaction (ddPCR) for different DNA tests has attracted much researchers’ attention. A large number of micron-sized droplets are required to perform ddPCR. In the present study, a ddPCR system was designed, fabricated, and evaluated using a microfluidic chip. The system comprises a microfluidic chip for droplet generation and a thermal cycling device needed for PCR. The droplet generation in the microchip was simulated in 3D. The simulation results were validated. The average error is about 5% in the radius of the droplets. The constructed thermal cycling device controls the chip temperature with a precision of ±1.5°C. The in-chip PCR process was successfully performed by applying 25 heat cycles. The fluorescent property was observed in most droplets that prove the thermal cycling device can provide the conditions for DNA proliferation in the laboratory. The images were processed, and different levels of fluorescent light were identified in the droplets. The coefficient of variation of the selected droplets is 2.5%, which gives a good accuracy compared to the acceptable amount for these types of systems (less than 8%). The results obtained from this fully native device can be used in many fields, including cancer detection, examination of malignant tissue, and evaluation of the success in tissue surgery.