A Quadruple Hole Resonant Cavity based Optical Pressure Sensor for Blood Pressure Measurement

This day and age, blood pressure (BP) is one of the serious cardiovascular diseases. For the continuous monitoring of BP, a small, light weight and cuff less device is needed. A new photonic crystal based optical pressure sensor is designed for observing of blood pressure. Concept of developing photonic pressure sensor is based on surface sensing principle, when an exterior tension is applied on the outer face of sensor, it is spread evenly in the form of strain and vary the geometrical parameters of sensor hence the resonance wavelength is shifted and is sensed by the optical sensor. The sensor is designed through a 2D-ordered triangular lattice structure. To obtain very high-quality factor and good light confinement, quadruple hole resonant cavities with four scattering rods are introduced into the linear waveguide. The designed sensor can monitor pressure from 0 kPa or 0 mmHg to 50 kPa or 375 mmHg and its operating ranges lies between the optical C and S band. It has very high quality factor 1721, high sensitivity 25 µm/KPa and low minimum detectable pressure 3.98e-7 nN. Over all, the proposed approach provides a new sensing system for the human blood pressure monitoring which have high selectivity, low cost, light weight and easy to use. The band gap of the PCs structure has been computed by plane wave expansion (PWE) method. The transmitted power and resonant wavelength are calculated with the help of finite difference time domain (FDTD) algorithm.