Abstract
We propose the use of CMOS-MEMS technology to fabricate a monolithically integrated pressure sensor intended for blood pressure monitoring during balloon angioplasty. Due to the small device size, a low sensitivity is expected. We employ a capacitive sensing circuit to convert the pressure-induced capacitive change to a shift of the oscillation frequency. The post-fabrication steps after completion of the CMOS include the use of a bio-compatible Parylene coating on top of the membrane, and a sacrificial metal etch to release the micromechanical membrane underneath the Parylene. In some design the readout circuit is a CMOS oscillator which can be placed directly underneath the membrane to save chip area. Our current design shows a sensitivity of 421 kHz/fF.