In-Plane Vibration of Hammerhead Resonators for Chemical Sensing Applications.

Thermally excited and piezoresistively detected in-plane cantilever resonators have been previously demonstrated for gas- and liquid-phase chemical and biosensing applications. In this work, the hammerhead resonator geometry, consisting of a cantilever beam supporting a wider semicircular "head", vibrating in an in-plane vibration mode, is shown to be particularly effective for gas-phase sensing with estimated limits of detection in the sub-ppm range for volatile organic compounds. This paper discusses the hammerhead resonator design and the particular advantages of the hammerhead geometry, while also presenting mechanical characterization, optical characterization, and chemical sensing results. These data highlight the distinct advantages of the hammerhead geometry over other cantilever designs.