Sensing Hydrogen Gas from Atmospheric Pressure to a Hundred Parts per Million with Nanogaps Fabricated Using a Single-Step Bending Deformation

The widespread use of H 2 gas as an energy carrier will necessitate the development of inexpensive, easily manufactured sensors which reliably monitor gas levels where H 2 is used, transported, and stored. Nanogap sensors transduce the volume expansion which accompanies hydrogen uptake by palladium-based metal-hydrides into an electrical signal through the closure of nanogaps which allows a previously interrupted current to flow. While this break-junction design offers numerous functionalities, limitations still exist in terms of fabricating nanogap sensors responsive to a wide range of partial pressures. Here, we invoke a detection strategy where up to 10 000 nanogaps of various widths act in concert to provide an overall analog signal which continuously varies as the H 2 partial pressure is varied from a hundred parts per million to 1 atm. The sensor is fabricated by mechanically coupling an AuPd film to a support consisting of polyimide, an adhesive, and a steel backing which, when bent, forms parallel cracks in the film which act as nanogaps. With characteristics that include room temperature detection, a high sensitivity and selectivity toward H 2, low-cost lithography-free fabrication, recyclability, low power consumption, simple circuitry, and favorable aging characteristics, the device meets many of the criteria needed for practical H 2 sensing.