Single-Pmut Sensor for Proximity-Tactile Sensing: Tof Distance and Contact Detection Via Cavity Resonance

We present a single piezoelectric micromachined ultrasonic transducer (PMUT) sensor that unifies proximity ranging and contact detection toward fingertip integration. Proximity is obtained by Time-of-Flight (ToF) ultrasound. Contact is detected because object loading compresses the rear cavity, reducing its volume and shifting the PMUT resonance; the resulting spectral/voltage change is used as a contact indicator. Consolidating both modalities in one MEMS device reduces footprint, wiring, and power compared with multi-sensor stacks. We demonstrate ToF ranging up to near contact and reliable contact detection within the same structure.