A microfluidic chip based on surfactant-doped polydimethylsiloxane (PDMS) in a sandwich configuration for low-cost and robust digital PCR

Digital PCR (dPCR) is a powerful method for the absolute quantification and rare mutation detection of nucleic acids. However, the available dPCR platforms require either expensive instruments or complicated operation, which limit their extensive application. This paper describes a robust self-partition chip to perform dPCR in a very simple and inexpensive format. The chip is constructed by sandwiching a micromolded surfactant-doped PDMS layer between two glass slides, containing 10,000 reaction compartments (0.785 nL each). The two simple strategies, “glass-PDMS-glass” sandwich configuration and surfactant-doped surface modification, are used to enhance PCR compatibility and enable efficient amplification in the chip by minimizing water loss and nonspecific adsorption of protein. Furthermore, powered by pre-degassing of its PDMS substrate and an attached PDMS slab, the chip autonomously loads and partitions sample into a high-density array of microwells for performing dPCR analysis. We evaluated the quantitative capabilities of the dPCR chip by measuring a ten-fold serial dilution of genomic DNA from lung cancer cell line H1975. Finally, we also demonstrate its feasibility in the accurate measurement of small copy number variations, which exhibited better accuracy than real-time quantitative PCR (qPCR). Such simple and low-cost platform promises to accelerate the widespread use of dPCR.