A Single Cell PMUT as a Bio-Fluid Density Sensor

A compact single cell piezoelectric micromachined ultrasound transducer (PMUT) with dual electrodes is designed, fabricated, and used to measure the density of a fluid mixture mimicking the range of human blood density variation. The sensor's novelty lies in its compactness enabled by on device sensing and actuation due to the dual electrodes. The active material used here is thin film PZT which is protected from the fluid environment with an appropriate coating. The results obtained show a linear response of the sensor output over the density range of interest with no appreciable degradation in the signal due to immersion in a fluid. The sensitivity of the sensor is 191 Hz/Kg/m 3 . These single cell PMUTs are, therefore, potential candidates for fluid density monitoring in industrial or biomedical applications.