Flexible piezoelectric liquid volume sensor

We report a non-contact type polyvinylidene fluoride (PVDF)-based liquid volume sensor. When a liquid container vibrates due to an applied impact, our sensor that is attached to the wall of the container detects the resonance frequency of vibration, which shifts as a result of change in liquid volume. The sensitivity of our sensor was enhanced by stacking multiple sensors in series. A PVDF bimorph actuator was also fabricated to demonstrate an integrated actuator-sensor system. We believe that the results presented in this work will pave the way for novel applications in volume sensing.