Integrated polymerase chain reaction chips utilizing digital microfluidics

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Abstract
This study reports an integrated microfluidic chip for polymerase chain reaction (PCR) applications utilizing digital microfluidic chip (DMC) technology. Several crucial procedures including sample transportation, mixing, and DNA amplification were performed on the integrated chip using electro-wetting-on-dielectric (EWOD) effect. An innovative concept of hydrophobic/hydrophilic structure has been successfully demonstrated to integrate the DMC chip with the on-chip PCR device. Sample droplets were generated, transported and mixed by the EWOD-actuation. Then the mixture droplets were transported to a PCR chamber by utilizing the hydrophilic/hydrophobic interface to generate required surface tension gradient. A micro temperature sensor and two micro heaters inside the PCR chamber along with a controller were used to form a micro temperature control module, which could perform precise PCR thermal cycling for DNA amplification. In order to demonstrate the performance of the integrated DMC/PCR chips, a detection gene for Dengue II virus was successfully amplified and detected. The new integrated DMC/PCR chips only required an operation voltage of 12VRMS at a frequency of 3 KHz for digital microfluidic actuation and 9VDC for thermal cycling. When compared to its large-scale counterparts for DNA amplification, the developed system consumed less sample and reagent and could reduce the detection time. The developed chips successfully demonstrated the feasibility of Lab-On-a-Chip (LOC) by utilizing EWOD-based digital microfluidics.