Optimization and design of bending‐insensitive paper‐based LC wireless passive sensors

Abstract How to monitor the freshness of packaged food, the safety of sealed medicine, or the other substances in sealed space wirelessly and environment‐friendly has become an urgent problem in recent years. After summarizing the theory of the LC sensor, a design of a paper‐based resonator (30 mm × 30 mm × 0.15 mm) consisting of a finger capacitor is proposed in this paper. The sensor is embedded inside the package by adhering it to the package's inner wall. Its response is remotely detected through a readout coil. This paper establishes a circuit simulation model and an electromagnetic simulation model to verify the feasibility of the design. Compared with the real object and the theoretical simulation model, the difference between the results only within 1 MHz, which verifies the correctness of the theory. Additionally, the measured results indicate that the resonant frequency of the resonator shifted from 102.441 MHz to 88.195 MHz, after dropping water on the sensor. Besides, the simple fabrication technology and inexpensive sensor material ensure a low cost, thus making this technology economically viable.