High-Performance Filament Strain Sensor Based on CNT-TPU-TPS with a Double Percolation Network

Flexible filament sensors have gained significant attention in wearable, electronics and smart textiles. However, achieving both high sensitivity and flexibility remains challenging, due to the oversimplified thin film structure of the strain sensor. In this work, a high-performance filament strain sensor is developed using a composite of carbon nanotube (CNT), thermoplastic polyurethane (TPU), and thermoplastic elastomer based-styrene (TPS). These filaments are fabricated through a combination of solution mixing and twin-screw extrusion. The sensor demonstrates excellent durability and high sensitivity, at a composition of TPS(90%)-TPU(10%) achieving a maximum gauge factor (GF) of 305.50 at 20%-40% strain, significantly outperforming the composition TPS(50%)-TPU(50%) (GF of 8.55). The results demonstrate reliable strain sensing over a broad range and stable performance over 1000 loading/unloading cycles which make it suitable for wearable electronics and human motion monitoring applications.