Rapid assembly of multilayer microfluidic structures

We demonstrate rapid 3D-printed molding and assembly of two-sided PDMS devices. Advancing the 3D printed transfer molding technique from single-sided microfluidics to multi-layer microfluidic manufacturing, this work utilizes the ease of 3D printing to create complementary molds with built-in alignment structures to PDMS layers and then assemble them at the end. Using this single-step double-sided molding method, we demonstrate the molding of complex geometries in PDMS — including vias, built-in alignment marks, and membrane valves — that are difficult or impossible to achieve using standard soft lithography. The membrane valves show distinctive transistor characteristic curves and a closing pressure of 200 kPa. A new stamp-bonding method is used to selectively apply liquid PDMS adhesive, demonstrating a reliable method of assembling multi-layered PDMS microfluidic devices.