Integrated and reusable in-plane microfluidic interconnects

A concept for reusable, in-plane polymer microfluidic interconnects that are directly integrated into microfluidic systems is reported. Convenient, on-demand world-to-chip interfaces are established by utilizing a pin-and-socket approach in which commercially available non-coring syringe needles are manually inserted through predefined polydimethylsiloxane (PDMS) septa integrated at the inlets/outlets of microchannels. Receptacles for the septa were batch-fabricated in a single layer of SU-8 that also formed microchannels in the microfluidic system. Due to the self-sealing nature of PDMS, the septa were used repeatedly and withstood multiple needle insertions and removals without leakage. Needle pull-out force was modeled as debonding in a fiber/matrix system and evaluated experimentally both in single and multiple pull-out studies. Results were compared with other published interconnects of similar construction. Interconnects were also evaluated under pressurized conditions and tested to failure. The simple format of these interconnects is readily adapted to many microfluidic fabrication processes and thus can be easily incorporated into existing microfluidic systems.