A low cost optical hydrogen sensing device using nanocrystalline Pd grating

A Pd grating of periodicity of 1.5 μm comprising of 1 μm wide nanocrystalline Pd lines has been obtained by a direct micromolding method to serve as Hydrogen sensor element in an optical diffraction set up. The device uses a low power diode laser and a photodetector and works with sensitivity of ∼20%. The hydrogen sensing action is based on monitoring the changes in the diffraction efficiency (DE) which is defined as the ratio of the first and the zeroth order diffracted beam intensities. The diffraction efficiency undergoes large and sudden changes as the nanocrystalline grating becomes disordered due to PdHx formation, as monitored using in-situ microscopy and optical profilometric measurements. This is truly a low cost, portable hydrogen sensor meant for large installations.

► We have developed a new hydrogen sensing device based on the optical diffraction technique. ► The sensing material is a nanocrystalline Pd grating, fabricated by a simple direct micromolding method. ► The fabricated sensor works repeatedly over a wide concentration range (1–100% H2). ► The device is portable, inexpensive and consumes low power. ► It is ideal as on-site sensor which can operate in proximity to the possible point of leak.