Temperature Capacitive Sensors Based on Liquid Crystalline Gels

Abstract Capacitive temperature sensors are attractive for soft and wearable electronics due to their low power consumption and simple architecture, yet their sensitivity is typically limited by the weak thermal response of conventional solid dielectrics. Liquid crystals, exhibiting strong temperature-dependent properties, represent a promising strategy to overcome this limitation, but their intrinsic fluidity compromises mechanical robustness and long-term stability. Here, we present a capacitive temperature sensor based on a liquid crystal gel (LCG), in which a low-molecular-weight nematic liquid crystal is stably confined within a nanoporous, crosslinked polymer matrix. The LCG acts as an active thermo-responsive dielectric, enabling a synergistic dual transduction mechanism that combines temperature-induced liquid crystal reorientation with a concurrent thermally driven contraction of the polymer scaffold. The thermal stimulation produces a dielectric–mechanical response improving the capacitive variation compared to solid polymer dielectrics and pure liquid crystal systems, both retaining the liquid crystal phase and ensuring mechanical integrity and leak-free operation during several heating–cooling cycles. Ambient and liquid temperature sensing is herein demonstrated, confirming the stability of the liquid crystal confinement in the gel matrix. This work establishes LCGs as a robust and versatile material platform for capacitive temperature sensing in applications that require easy manufacturing, customizable designs, and low costs. In parallel, it opens up further routes for sensing of other physical entities.