Liquid Metal Elastomer Resonant Sensors for Frequency-Domain Distributed Strain Sensing

Abstract

Traditional sensor arrays face the trade-off dilemma between distribution density and circuit complexity, while strain sensors suffer from weak circuit stability under flexible deformation. Here, we propose a liquid metal elastomer resonant (LMER) sensor for frequency-domain distributed strain sensing, which employs liquid metal elastomers as the sensing elements and an RLC series circuit as the core component. The sensor enhances frequency selectivity and resonance-response stability by precisely regulating inductance and capacitance parameters, enabling stable and distinguishable resonant-frequency shifts under flexible deformation and thereby achieving efficient conversion from mechanical strain to frequency-domain signals. Experimental results demonstrate that the three LMER sensing units exhibit highly linear resonant-frequency-shift responses (R² > 0.99) within the core compressive strain range of 0–30%, along with low rate dependence (<0.5%) and excellent long-term cyclic reliability, with frequency-response attenuation below 1% after 10,000 cycles. Furthermore, a distributed sensing system is constructed based on the parallel integration of LMER sensors with distinct resonant-frequency windows, enabling spatially distributed strain responses to be discriminated in the frequency domain through a shared signal line. This work establishes a frequency-domain distributed strain-sensing strategy based on LMER sensors, offering a compact and stable route for distributed flexible sensing in applications such as human–computer interaction, soft robotics, and wearable devices.