Non-lithographically microfabricated capacitive pressure sensor for biomedical applications

A novel micromachined capacitive pressure sensor fabricated on a metal substrate without using a photolithographic process is reported. The device is constructed by thermal bonding of a Parylene membrane onto a 1.5 × 1.5 × 0.2×mm³ stainless-steel chip with a shallow cavity created using micro-electro-discharge machining. The fabrication approach enables rapid, low-cost manufacturing of the device with biocompatibility. The sensor is designed to provide a gauge pressure range of 200 mmHg or greater to be potentially suitable for invivo blood-pressure sensing applications. A highly linear response of 2 fF/mmHg is demonstrated with the fabricated devices. The temperature coefficient of the sensor is observed to be 250 ppm/ °C.