Flex‐circuit resonant chip with Y5V multilayer capacitor for wireless temperature tracking

This paper reports the first wireless thermometric device enabled using a surface-mount capacitor microchip as the sensing element, offering a low-cost, disposable, and flexible sensor potentially suitable for a wide range of application areas. The device is developed in the form of a resonant-circuit chip, in which a Y5V-type multilayer capacitor microchip that exhibits significant temperature dependence serves as a thermoresponsive element that varies the resonant frequency of the circuit upon a temperature change. The wireless sensor chips prototyped in conjunction with the flex-circuit technology are tested to show their intended function with the frequency responses of up to 129 kHz/°C for ambient temperature variations. Wireless temperature tracking of a fluid-flowing channel is experimentally demonstrated using the prototype.