Simulation and demodulation of an airway pressure sensor based on Fabry-Perot interference

In this paper, a highly sensitive airway pressure sensor based on Fabry-Perot interference principle is proposed. The sensor is fabricated by metallic silver film, zirconia ceramic casing, zirconia ceramic ferrule, single mode fiber, and copper nickel-plated tailstock, which meet the chemical stability requirements of medical device. The overall model design and local finite element simulation analysis of the sensor are performed. First, the solid mechanics module of COMSOL is used to emulate the distortion of the film at different pressure to obtain the respective sensor cavity length. Second, the reflectance spectra corresponding to different sensor cavity lengths are obtained using the fluctuating optical module of COMSOL. Thus, the correlation between pressure and spectral offset can be derived. The average spectral sensitivity of the sensor under pressure is obtained to be -1.68 nm/KPa. On this basis, the demodulation method of F-P sensor is explored. The spectral peak tracking principle is applied to the wavelength demodulation of reflection spectrum. The cavity length sensitivity of the sensor is calculated -570.197 nm/KPa. By comparison, the spectral sensitivity after demodulation is obviously improved. The sensor exhibits potential applications in the areas of airway pressure measurement and environmental surveillance.