Photofabricated channel-digital microfluidics (pCDMF): A promising lab-on-a-chip platform for fully integrated digital PCR

Microfluidics-based digital PCR (dPCR) is a potent technique capable of absolute quantification of nucleic acids with ultrahigh sensitivity. However, an indispensable process, nucleic acid extraction (NAE) remains hard to be integrated with dPCR into a monolithic device, because both of them involve complicated processes and exquisite fluid manipulation. An ideal solution to this issue is to integrate the two main microfluidic platforms, channel-based microfluidics (CMF) and digital microfluidics (DMF), which, however, remains very challenging. To address these challenges, we herein develop a photofabricated channel-digital microfluidic chip (pCDMF) with significant advantages including: the fabrication of pCDMF is very convenient due to the flexible material choices of photocuring, without tedious process of hydrophobic coating; a parallel-plate configuration can be easily formed, enabling all basic functions of DMF; various channels and microstructures can be freely designed, allowing for fluidic functions of CMF. It is therefore the first example of full integration of DMF and CMF as a monolithic device, with capabilities to precisely handle both discrete droplets and continuous fluids. Finally, an all-in-one device for sample-to-answer digital PCR has been successfully demonstrated. We also envisioned that the pCDMF may open an alternative route toward the fully integrated lab-on-a-chip for various biological applications.