A Radiofrequency Threshold Temperature Sensor Using a Hf0.5Zr0.5O2 Device and a Microacoustic Piezoelectric Resonant Sensor

This article presents the first prototype of a novel threshold sensing system operating in the radiofrequency (RF) range, capable of passively detecting and recording instances of temperature violations with high sensitivity and without the need of DC-biased memory devices. The system comprises a microfabricated hafnium zirconium oxide (HZO) ferroelectric varactor, a microfabricated lithium niobate (LiNbO3) shear-horizontal (SH0) Lamb wave microacoustic resonator used as a temperature sensor, and an inductor. All components have been soldered onto a printed circuit board for testing and characterization. Through this threshold sensing system, we also provide the first demonstration of ferroelectric switching in a HZO varactor triggered exclusively by an RF signal without requiring any DC voltages. The findings reported in this paper offer a promising pathway for future RF passive tags leveraging micro- and nanosystems to implement a programmable threshold sensing functionality with high sensitivity and with embedded memory capabilities. [2023-0215]