Chipless wireless temperature sensor based on quasi-BIC resonance

Wireless sensors find use in many practical applications, where wired connections possess a limitation. New realms of global connectivity and data exchange among various devices suggest putting a sensor on a consumable level, where electronic circuits are not affordable from an economic standpoint. Chipless approaches, aiming to address the later issue, typically come with a penalty of performance degradation and, in many cases, is seen as a compromise solution. Here, we demonstrate a concept of the extremely sensitive temperature sensor based on the bound states in the continuum (BIC) approach. A ceramic half-cylinder above a ground plane is designed to support high quality factor supercavity modes with a strong resonant dependence on an ambient temperate. The operation of the sensor is experimentally demonstrated in a broad range of temperatures, spanning from 25 to 105 °C with an average sensitivity of 4 MHz/°C. The key element, leading to this performance, is high-quality ceramics, which allows supporting confined modes with moderately low Ohmic losses and extremely high-quality factors above 1000. High-performance chipless devices, which are capable to accommodate several functions with a single platform, open a venue to a new generation of wireless distributed sensors, where the main technological and outlay efforts are placed on an interrogation side.