A H2 microsensor based on nanocolumnar tungsten oxide grown by template-assisted anodization

Sensors embedded in micro fuel cells can help in controlling some important parameters such as temperature, humidity or gas concentration. In this paper we introduce the fabrication procedure for MEMs-compatible nanocolumnar tungsten oxide gas microsensors and show the results of measuring their responses to H₂, CO and humidity. Tungsten oxide nanoculumns were grown by smart anodization of Al/W layers on silicon micro-hotplate substrates. An excellent linear sensor response was observed for hydrogen in the 0-20 ppm concentration range and a low response to CO and moisture in the usual operating conditions of micro fuel cells. The sensors operated at moderate temperature due to the high surface-to-volume ratio and the nanostructured morphology of the sensing films.