Very large scale arrays of chemo-mechanical nanoswitches for ultralow power hydrogen sensing

We present a novel hydrogen sensor that is based on large arrays of chemically actuated electromechanical nanoswitches, realized by nanogaps in palladium (Pd). An individual switch consists of a trimorph poly-Si/Ti/Pd structure and a fixed Ti/Pd electrode, separated by an approximately 10-15 nm wide nanogap. The volume expansion of Pd at hydrogenation bends the trimorph vertically and creates an electric contact with the electrode. The fabrication process enables the parallel fabrication of many nanoswitches in arbitrary topologies. Hydrogen is detected by current changes up to three orders of magnitude at room temperature and a power consumption of down to pW.