Polymer (SU-8) optofluidic device with embedded hydrogel oxygen sensing elements

The SU-8 photopolymer is an excellent alternative for traditional materials used in fluidic devices such as glass- or silicon-based inorganic materials. We describe a new chemically-anchored, lithographically-patterned hydrogel sensing element embedded in a completed SU-8 fluidic channel structure after the channel bonding process. Polyethylene glycol (PEG) hydrogel films incorporating oxygen-responsive ruthenium-complex fluorophores are grafted and patterned by photopolymerization of solution-phase precursors on the modified SU-8 channel surface. The optofluidic sensing platform with this embedded sensing elements exhibited excellent performance in measuring dissolved oxygen content. A unique advantage of this method is the selective growth of various functional films in situ by sequentially injecting different precursors. This fluidic sensing platform will be a viable component for both electrochemical and optical bioanalytical assays.