Influence of Bending on the Frequency Responses of LC Sensors

This study delves into the alterations in resonant frequencies due to bending in flexible sensor applications. We examined the resonant frequencies of four inductor–capacitor (LC) resonant circuits subjected to various bending conditions and assessed the performance of LC temperature sensors under different bending states. Optimization of the sensor coil parameters was achieved through finite element simulations. LC resonant circuits were fabricated on flexible Pi films utilizing an inkjet printing technique, followed by bending tests. Our findings indicate a rise in the circuit’s resonant frequency as the bending radius diminishes. Separate simulations for capacitors and inductors revealed that the factors influencing the shift in resonant frequency after bending vary across LC sensors with different architectures. Additionally, we evaluated two configurations of LC temperature sensors in bending states. Notably, the reel-type LC temperature sensor, designed for direct winding at the temperature measurement site, demonstrated a measurement sensitivity of 89.3 KHz/°C, presenting a pioneering approach for temperature assessment in constrained, enclosed, and curved environments. The insights gleaned from this research are instrumental for the design and optimization of flexible sensors in practical applications.