Implantable resonant mass sensor for liquid biochemical sensing

This paper describes an implantable, resonant mass sensor (built on a micromachined probe with a piezoelectric thin film) for liquid mass sensing. The sensor is basically a film-bulk-acoustic resonator (FBAR) with a piezoelectric ZnO film and two Al layers sitting on a silicon nitride (SiN) diaphragm, which forms the tip portion of an implantable silicon probe for recording neuronal activities in a living biological tissue.