Sensor Application of Poly (Ethylene Glycol) Diacrylate Hydrogels Chemically-Anchored on Polymer Surface

We demonstrate a device process combining two photopatternable polymers, poly (ethylene glycol) (PEG)-diacrylate-based-hydrogel and epoxy-based photoresist SU-8, to implement a optofluidic bioanalytical platform through a surface anchoring technique. As an exemplary sensor application, optical dissolved oxygen sensors are fabricated and their performance characterized. The PEG-rich hydrogel is used as a matrix material for the immobilization of oxygen-responsive fluorophore, dichlorotris (1, 10-phenanthroline) ruthenium (II) hydrate. This hydrogel is chemically-anchored on the surface of negative-tone photoresist, SU-8, through a free radical reaction in which 1-hydroxycyclohexyl phenyl ketone served as the surface bound photoinitiator. The sensor exhibits a reversible Stern-Volmer response and good storage stability. Cylindrical hydrogel sensing elements are then patterned and anchored within completed SU-8 fluidic channels to serve as the embedded sensing elements in optofluidic platforms. We anticipate that the proposed method has a variety of applications that require the immobilization and patterning of biorecognition agents in hydrophilic matrices within completed polymeric fluidic channel.