Multimodal Double-Helix Fiber Sensors for Distinguishable Pressure and Strain Detection in Wearable Sensory Applications

Fiber sensors with an engineered architecture offer a compelling platform for next-generation wearable electronics, owing to their inherent mechanical adaptability and compatibility with textile integration. In this study, a multimodal fiber sensor with a one-dimensional double-helix architecture is introduced, enabling the distinct detection of pressure and strain stimuli within a single device. Strain sensing is realized via piezoresistive changes in a helical conductive fiber, while pressure is detected through piezocapacitive responses between two twisted fiber electrodes separated by a dielectric layer. This structural configuration ensures effective decoupling of signals, yielding a reliable dual-mode operation without cross-interference. The strain-sensing component demonstrates a gauge factor of 0.03 ± 0.001%^-1, high linearity (0.996-0.999), negligible hysteresis, rapid response (∼300 ms) and recovery (∼350 ms) times over a broad strain range (0-300%), and stable performance over 2500 cycles. The pressure sensor exhibits a gauge factor of 0.001 ± 2 × 10^-5 kPa^-1, excellent linearity (0.992), fast response (∼150 ms), and mechanical durability of over 2500 cycles. Practical demonstrations─including joint motion, respiration, tactile force, and airflow detection─validate the sensor's multimodal functionality. By integrating high fidelity, minimal signal interference, and robust structural performance, the proposed double-helix fiber sensor presents a versatile and scalable solution for wearable multimodal sensing applications.