A monolithic photonic microcantilever device for in situ monitoring of volatile compounds

A monolithic photonic microcantilever device is presented comprising silicon light sources and detectors self-aligned to suspended silicon nitride waveguides all integrated into the same silicon chip. A silicon nitride waveguide optically links a silicon light emitting diode to a detector. Then, the optocoupler releases a localized formation of resist-silicon nitride cantilevers through e-beam lithography, dry etching and precisely controlled wet etching through a special microfluidic set-up. Fine micro-optical sensing functions are performed without the need for any off-chip optics. As the bimaterial microcantilevers are deflected by the stressed polymer film, the disrupted waveguide acts like a photonic switch. Cantilever deflections in the order of 1 angstrom caused by thickness variations in the order of 0.005 angstrom are detectable following changes in the physicochemical factors affecting the polymer film thickness. Such factors include the sorption of volatile compounds and through a proper set-up the response to certain vapor concentrations is monitored in real time.