Fibrous Pressure Sensor with Unique Resistance Increase under Partial Compression: Coaxial Wet‐Spun TiO ₂ /Graphene/Thermoplastic Polyurethane Multi‐Wall Multifunctional Fiber

Abstract

Abstract Fiber‐shaped resistive pressure‐sensitive sensors are rare. Although fibers are widely used in strain sensors owing to their structural advantages, developing fiber‐shaped resistive pressure sensors is challenging. This challenge arises because the fiber acts as a series circuit along its axis, requiring increased resistance in the compressed region for a significant signal. Coaxial wet‐spinning is used to create a multi‐walled fiber. The outer layer, made of thermoplastic polyurethane (TPU)/TiO 2 slurry, ensured a smooth surface, while the inner core, containing 4% graphene nanoplatelets (GNPs), is extruded at 20 mL h −1 . Unlike conventional resistance‐increasing pressure sensors, TGTMW fiber shows rising resistance under compression due to microcracks in its multi‐wall structure. Its pressure sensitivity is evaluated using various 3D‐printed indenters and showcasing its excellent performance. This sensor has found promising applications in remote motion detection, press or slide differentiation through wavelet transforms applied to high‐speed sensing data, and real‐time signal acquisition from a multi‐channel sensing array. Additionally, intuitive visualization software is developed for the sensing array application and implemented a CNN‐based machine learning algorithm for data analysis. The system achieved a recognition accuracy of ≈99.6% for 12 different compression modes. This work is believed to propose a new mechanism and design for fiber‐based pressure sensors.