Small-Size High-Resolution Ambient Temperature Sensing based on iTOF Piezoelectric Micromachined Ultrasound Transducers

This work introduces a miniaturized ambient temperature sensor using piezoelectric micromachined ultrasound transducers (PMUTs) and indirect time-of-flight (iTOF) measurement. Leveraging phase-difference calculations at high ultrasound frequencies, the method overcomes size and resolution limitations of conventional direct TOF approaches. A compact 3-cm prototype demonstrates immunity to thermal interference and achieves a high temperature resolution of 0.02°C. This iTOF-PMUT platform enables reliable ambient sensing for portable applications.