Hydrogen is one of the possible replacements for fossil fuels in the future. However, appropriate safety barriers are required due to hydrogen’s high flammability and diffusivity. One such barrier is a flexible detector for hydrogen leaks. Commercially available detection tapes can be wrapped around hydrogen-carrying equipment such as pipe flanges or valves. The tape detects hydrogen leaks by changing color. Such tapes require visual observation to detect leaks, and camera-based observations are prone to errors due to blind spots. In contrast, chemiresistive hydrogen detectors can continuously read the detector output and signal an alarm accordingly. Palladium (Pd) is commonly used to fabricate chemiresistive sensors due to its high selectivity towards hydrogen. Under ambient conditions, palladium can absorb hydrogen to form a hydride, which has a higher electrical resistance than pure palladium. This increase in resistance is indicative of the presence of hydrogen. Thus, a flexible chemiresistive leak detector can signal the presence of hydrogen without depending on visual observation. Detectors having faster responses enable early leak detection, thereby decreasing the risk of accidents Palladium nanostructures have exhibited fast response times and have been widely studied. Thin polymer sheets like polyimide have excellent dielectric properties and heat resistance. Large-area polyimide substrates are also commercially available at a low cost, thereby being useful as a substrate material for flexible leak detectors [4]. In our work, electrically conductive Pd nanostructures were deposited on polyimide using a novel bottom-up fabrication technique under ambient conditions. The detectors prepared thus could repeatedly respond (t90 < 30 s @ 0.6% H2) and recover to step-changes in hydrogen concentration, with air as the carrier gas. The detector response time showed good durability after five months of inactivity at ambient storage.
