Mass-Sensitive Gas Detectors Based on Bulk Micromachined Silicon Cantilevers Coated by Carbyne-Enriched Nanolayer

Cantilever elements were designed and fabricated by silicon microfabrication technologies to create gas sensor architecture, employing a novel class of carbyne-enriched nanomaterial. It was intended to explore the potential of the element as a sensitive sensor of volatile organic compounds (VOCs), in particular of ethanol vapors. The fabrication technology was described in detail and the mass sensitivity and response times were compared for cantilever structures with different beam lengths. The carbyne-enriched nanolayer was deposited on the silicon cantilevers by ion-assisted pulse-plasma deposition. The results showed better sensitivity and broader linear dynamic range for the longer beam cantilever of 240 μm (0.71 mHz/ppm vs. 0.3 mHz/ppm), but shorter response and recovery time, as well as smaller hysteresis for the shorter beam cantilever of 200 μm (14.8/17.5 s vs. 16/27.9 s). This is the first demonstration of the novel coating implemented in a practically useful ethanol sensing structure with electromagnetically driven, mass-sensitive principle of operation and possible application in the food industry, medicine, pharmacology, or microelectronic industry.