Application of Flexible Piezoelectric Micromachined Ultrasonic Transducer Array for Object Detection

This work presents a flexible 3 × 3 piezoelectric micromachined ultrasonic transducer (PMUT) array designed for reconfigurable air-coupled object detection. The array operates at 230 kHz with four independently controlled channels and can be configured into flat, concave, or convex geometries to adapt its sensing characteristics. Finite element modelling in COMSOL was employed to analyse beam steering, scattering behaviour, and aperture effects, providing design guidance and synthetic data for algorithm development. Experimental validation was performed using a pulse-echo setup with a 2 cm target placed at distances ranging from 5 cm to 1 m. Results show that the concave mode enhances focusing and echo amplitude, the convex mode extends the field of view for initial detection, and the flat mode achieves accurate localization with ~2 cm lateral resolution at a 10 cm range. The combined modelling and experimental results demonstrate the potential of reconfigurable flexible PMUT arrays as compact, low-power, and high-resolution ultrasonic sensors for robotics, automation, and VR/AR applications.