Our new microfabrication process can integrate electronics into plastic devices, simplifying on chip sensing and actuation. Traditional microfluidic prototyping (PDMS soft-lithography) requires large off chip components for active flow control. These components impose scalability limitations. Leveraging thermo-gelling polymers and integrated resistive heaters we can implement on chip active flow control. These polymers, poloxamers, are nonionic triblock copolymers known for their temperature dependent self-assembling and thermo-gelling behavior. Poloxamers can quickly (30ms) undergo a phase transition into a gel-like substance over a temperature change of two degrees Celsius. The viscosity rapidly increases by 1000-fold, effectively stopping flow. Furthermore, the transition temperature can be easily adjusted by varying poloxamer concentration, allowing for precise thermal control. Using targeted heating with our integrated resistive heaters, we can leverage the phase transition temperature to create rapid reversible valves. These devices expand microfluidic prototyping capabilities in fields such as mixers, fluidic logic, cell culturing, and imaging.
Project end date: 01/27/20