Flexible, biocompatible photoresists for fabricating electronic, in vivo, and microfluidic devices

Development of advanced electronic and microfluidic devices requires innovative photoresist solutions to fabricate these increasingly complex devices. Novel requirements on the properties of traditional photoresists may include mechanical flexibility, stretchability, dielectric stability, low water permeability, and small molecule absorption. Here, we introduce a novel series of perfluoropolyether photoresists (SNER: Soft Negative Elastomeric Resist) that are compatible with i-line photolithography techniques. Depending on the chemical formulation, the elastic modulus of the cured resist can be controlled in the range of 1 to 100MPa. The film thickness range is 0.1 to 200μm, with a 2 to 5μm resolution, and good adhesion to sputtered metal. Soft biocompatible microelectrode arrays realized with SNER showed year-long dielectric stability in physiological solutions, comparable to that of SU-8 2000, and significantly lower ionic permeability than polydimethylsiloxane (PDMS).