Application of spectral surface plasmon resonance for gas pressure sensing

A pressure sensor based on the spectral response associated with the surface plasmon resonance (SPR) occurring on a 50 nm gold surface is described. The operation of the device relies on the fact the refractive index of a gas changes with pressure. Since the conditions for SPR is extremely sensitive to refractive index variations, the pressure of the gas exposed to the sensor surface can be detected. In our spectral SPR sensor, such refractive index change leads to a shift in the spectral dip in the SPR curve. Experiments performed on nitrogen gas at room temperature has demonstrated that our trial setup has a sensitivity threshold of 8.33/spl times/10/sup -4/ RI units, which corresponds to a pressure change of 6.3 psi. We expect that further improvement may be possible if we use better spectral signal processing algorithm to locate the spectral dip with higher degree of accuracy.