On the Realization of Self-Sensing Piezoelectric MEMS Actuators

Three different configurations of self-sensing piezoelectric MEMS actuators are designed, fabricated, and tested with PZT as the active material. A two-port circular diaphragm resonator of radius 1000 μm, a cantilever of length 1000 μm and width-24 μm with two parallel top electrodes, and a four-legged resonator structure with a proof mass of total die size 1.6 mm × 3 mm are fabricated and characterized as self-sensing actuators without any cross-talk compensation. A comparison among the output signals reveals that the cantilever (without etching the PZT in between the two electrodes) and the four-legged resonator perform well as self-sensing actuators, while the two-port diaphragm resonator with large concentric top electrodes suffers from electrical cross-talk. A successful characterization of a self-sensing actuator with the common ground electrode (for cantilever) is being reported for the first time. Deflection values of as low as 1 nm could be easily resolved using the proof-mass resonator. The act of actuation is verified by directly measuring the motion with laser doppler vibrometry which cross-verifies the sensor signal produced by the piezoelectric layer.