Rugate-structured free-standing porous silicon-based fiber-optic sensor for the simultaneous detection of pressure and organic gases

Rugate-structured free-standing porous silicon was used as a membrane for a fiber-optic sensor. This material was suitable as a pressure sensitive membrane because it showed a strong peak in the reflectance spectrum which can be used for sensor signal processing and because its elasticity modulus could be easily controlled. The membranes showed an effective response in a low pressure range between 0.0 and −20.0 kPa. In addition, the membranes showed multiple responses to organic gases as well as different pressures due to their gas-sensing capability imparted by their highly porous structure.