High Performance and Low SWaP Oxygen Sensors based on Piezoelectric Micromachined Ultrasonic Transducers

For the first time, this paper presents an ultrasonic oxygen sensor based on piezoelectric micromachined ultrasonic transducers (PMUTs) with enhanced performance and reduced size, weight and power (SWaP). The proposed oxygen sensor contains two PMUT arrays, each operating at 340 kHz with chip dimensions of 1.5 × 3 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, placed on opposite sides of a pipeline to alternately transmit and receive signals. By measuring the time-of-flight (TOF) and the time difference between downstream and upstream signals, the sensor accurately determines oxygen concentration and flow. Experimental results demonstrate that the developed sensor achieves full-scale errors in concentration and flow of less than ±0.6% and ±1.2% (i.e., ±0.072 L/min), respectively, which are 3 times better than those of commercial ultrasonic oxygen sensors. It also features a volume of 43 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>, a weight of 6 g, and a power consumption of 0.6 mW, boasting significantly lower SWaP.