A Novel Flexible Blood Pressure Sensor Based on Ultrathin Silicon for Continuous Monitoring

Continuous blood pressure (BP) monitoring is essential for the early detection and effective management of cardiovascular diseases. Conventional photoplethysmography (PPG) sensors are limited by their susceptibility to ambient light conditions and a low signal-to-noise ratio, whereas piezoelectric sensors often face challenges in achieving close skin conformity due to their inherent rigidity. This study introduces an innovative flexible BP sensor based on 5 μm ultrathin silicon, designed for continuous monitoring. Encapsulated in Eco-flex 0030 and reinforced with fiberglass, the sensor maintains high sensitivity and precision. Finite element analysis is employed to optimize the encapsulation materials and dimensions. When affixed to the wrist, the sensor proves to be non-burdensome and non-irritating to the skin, effectively detecting radial artery pulses. To estimate blood pressure, reflective pulse transit time (R-PTT) is utilized. Calibration against a standard sphygmomanometer indicates a high degree of concordance between the systolic and diastolic pressures estimated from the collected signals and the actual measured values, thereby validating its reliability for cardiovascular monitoring. The findings suggest that this BP sensor offers a promising improvement in continuous, non-invasive blood pressure monitoring technology.