Enhanced Airborne Ultrasound WuRx Using Aluminum Nitride 4-Beam pNUTs Arrays

In this work, we present an implementation of a low-power wake-up receiver (WuRx) that is remotely interrogated by airborne ultrasound. The transduction from ultrasound to electrical signal is performed by arrays of aluminum nitride (AlN) 4-Beam piezoelectric nanoscale ultrasound transducers (pNUTs). Two set of arrays with a center frequency at 45 kHz and 49 kHz are used for two separate validations of the WuRx. The arrays interface with electronics implemented with affordable off-the-shelf (OtS) components for amplification and demodulation of the wake-up signal. The system has a power consumption of $27 ~\mu \text{W}$ , a modulation frequency of 1 kHz, and a minimum detectable pressure between 1.5 Pa and 0.6 Pa depending on the selected device. The individual pNUTs occupy an area of approximately $100 ~\mu \text{m}$ x $100 ~\mu \text{m}$ . A similar electronics architecture as the one presented in this document can be miniaturized to an area comparable to the one of the pNUT if implemented with integrated circuit (IC) technology, pointing to the possibility of integrating ultrasound WuRx into miniaturized, dust-like sensing platforms. [2021-0192]