Design of a novel MEMS implantable blood pressure sensor and stress distribution of parylene-based coatings

Implantable pressure sensors based on the silicon piezoresistive effect can enable accurate blood pressure measurement and real-time monitoring. In this work, a novel model of a piezoresistive pressure sensor was established with the design of piezoresistors laterally placed above the membrane, and the sensitivity could be calculated as 33.5 µV/V/kPa. In addition, implantable sensors usually need reliable coatings to protect them from corrosion by body fluids. Parylene-based coatings are thought to be biocompatible and waterproofing. Different parylene composite coatings have been simulated to determine their impact on the stress distribution. The parylene-silicone/polydimethylsiloxane (PDMS)-parylene structure showed a minimum stress difference of 1.12% compared to the unpackaged sensor, which might be a proper encapsulation method for implantable devices.