Lithography-Free Fabrication of Bimorph Nanostructural Chemomechanical Switches for Hydrogen Detection with Near-Zero Standby Power Consumption

This paper presents a contact-based chemo-mechanical switch for hydrogen (H2) sensing with near-zero standby power consumption, which activates only when the H2 concentration exceeds a specific threshold. The sensor features palladium (Pd)/chromium (Cr) bimorph nano-cantilevers fabricated using directional electrospinning and tilted angle deposition, eliminating the need for photolithography. Upon exposure to H2, the Pd layer absorbs the gas and undergoes volumetric expansion, causing the cantilever to bend. This mechanical deformation leads to contact between the structures, forming a conductive path that enables detection of H2 concentrations in the range of 0.5% to 4%. The sensor exhibited a high on/off current ratio exceeding 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> at concentrations above 0.5%, along with a low leakage current of approximately 7 pA in the off state. These results demonstrate the potential of the proposed device for simplified fabrication and energy-efficient H2 leak detection.