Novel solid-phase biosensors that utilize ink jet printing of biocompatible sol-gel based inks to create sensor strips are reported herein. Biomolecules and other reagents useful in bioassays to detect, for example, pathogenic microorganisms or toxic substances, are immobilized on a substrate, which can be paper based, by layering these substances between two layers of biomolecule compatible sol gel. The sol gel precursor solutions and solutions of the assay reagents are printed from separate nozzles in a layered approach which avoids clogging of the nozzles by the pre-mature gelling of the sol gel precursor solution. In certain embodiments of the application, a capture agent is used to concentrate a compound to be detected in specific areas on the substrate to facilitate detection.