A miniaturized wireless accelerometer with micromachined piezoelectric sensing element

• A piezoelectric wireless accelerometer for vibration monitoring.
• A micromachined sensing element comprising silicon beams and seismic mass.
• In-plane polarized ferroelectric thin film as the piezoelectric sensing layer.
• A low profile compact package design accommodating all functional modules.
• Appropriate package to eliminate the electromagnetic interference.

A miniaturized wireless accelerometer using a piezoelectric micro sensing element is designed, theoretically analyzed, and demonstrated for remote mechanical vibration monitoring. The micro sensing element comprises a micromachined monolithic silicon seismic mass and multiple silicon beams coated with in-plane polarized (Pb, La)(Zr, Ti)O3 (PLZT) ferroelectric thin film. A low profile compact package is obtained for accommodating all the micro sensing element, charge amplifier and signal processing circuits, radio frequency module, and battery. The electrical output linearly proportional to the vibration acceleration is amplified, digitalized and transmitted to a remote base unit through radio frequency communication. The effects of the device package on the dynamic response of the wireless piezoelectric accelerometer including shielding of ambient interference are investigated.