Optical Hydrogen Gas Sensors

Dr Mehdi Ranjbar
Department of Physics
Isfahan University of Technology
Isfahan, Iran

Recently, hydrogen has attracted much attention as a candidate for an alternative energy source to replace fossil fuels. Since hydrogen can explode in air, it is important to develop hydrogen safety sensors for use through the process of manufacturing, storing and utilizing hydrogen. One approach is to exploit the gasochromic properties, as an optical detecting, of some electrochromic thin films. These materials change color when exposed to hydrogen gas, so by monitoring the changes in optical transmission one can detect the presence of hydrogen. This approach has an advantage over other sensor technologies based on the measurement of electrical conductivities; the change in the optical transmittance can be measured remotely by using optical sensors to eliminate the electrical currents in the sensing area. This will ensure that the sensor does not introduce any additional ignition source because electric sparks can cause an explosion in a hydrogen leak. Several electrochromic materials, including oxides of tungsten and molybdenum also manganese oxide, have been studied for this application.