Monolithic silicon optical microdevices for biomolecular sensing

Here, we present monolithic silicon optocoupler array chips properly biofunctionalized to affinity biosensors. The optocouplers consist of monomode silicon nitride waveguides that optically link silicon LEDs and silicon photodetectors. The light emitters are silicon avalanche diodes that emit light when reverse biased beyond their breakdown voltage. The optical device is transformed to biosensor by spotting the waveguides with protein or DNA probes and by coupling a microfluidic compartment on top to allow for the supply of the reagents and the sample. Binding of the counterpart biomolecules changes the optical coupling efficiency and the detector photocurrent. The analytical performance in detecting DNA and protein molecules both in labeled and non-labeled assay formats is described.