Ultra-sensitive, One-time Use Hydrogen Sensors Based on Sub-10 nm Nanogaps on an Elastomeric Substrate

Extremely narrow nanogaps with a width less than 10 nm have been achieved in Pd thin films on a PDMS substrate by the combination of tensile straining and fine control of initial hydrogen concentration. For the Pd/PDMS structures pre-elongated by 25%, the width of nanogaps was found to decrease with decreasing concentration of the initial feed of hydrogen gas. Hydrogen sensors based on the nanogaps with reduced widths resulted in a dramatic improvement in hydrogen detection limit, and the minimum detection limit obtained in this study was 10 ppm, which is the lowest ever reported for hydrogen sensors employing only a Pd thin film. These results provide an unusual opportunity to use these sensors in specific fields, where ultra-high precision hydrogen detection is required even with one-time use.