PDMS-Swelling Induced Microchannel Reshaping and Its Applications in Droplet Microfluidics

Droplet microfluidics can develop a miniaturized laboratory-on-chip system that integrates multiple biochemical processes, including sample preparation, reaction, separation, and detection within centimeter-scale devices. Although well-designed microchannels enable a wide variety of droplet generation applications, a stereotypical microchannel limits the flexibility of droplet applications. In this study, through the controlled infusion of organic solvents into microchannels, we induced PDMS matrix penetration and subsequent roof subsidence. Three functional microfluidic systems were successfully engineered using this approach: 1) A chaotic advection-enhanced droplet micromixer was constructed for generating heterogeneous flow patterns, which improved mixing efficiency by 72% compared to conventional designs. 2) A droplet multiplication system was constructed to achieve a high-flux droplet digital polymerase chain reaction (PCR). 3) A multivolume droplet-generation system was constructed for in-droplet 3D culture. This reconfigurable channel modification strategy provides researchers with unprecedented flexibility in developing adaptive microfluidic architectures, effectively broadening the scope of droplet microfluidics in biomedical research.