Methods for adhering a hydrogel matrix to a molded polymer substrate and its use as a biosensor, e.g., a continuous or episodic glucose monitor, are disclosed. The presently disclosed subject matter provides a method for adhering a hydrogel matrix to a molded polymer substrate, the method comprising: (a) molding a polymer comprising one or more polymer chains with an oxidizer to form a molded polymer substrate; (b) providing a hydrogel matrix comprising a hydrogel, a component comprising one or more acrylate groups or another functional group that can form one or more radicals upon polymerization in the molded polymer substrate, and a photo initiator; (c) combining the molded polymer substrate and the hydrogel matrix; and (d) curing the combined molded polymer substrate and hydrogel matrix for a period of time.