Recent Advances of Flexible Strain Sensors Based on Conductive Fillers and Thermoplastic Polyurethane Matrixes

Over recent years, flexible strain sensors have been playing an increasingly important role, especially in wearable electronics, healthcare equipment, electronic skins (e-skins), and soft robots. Numerous materials are utilized in these applications; however, thermoplastic polyurethane (TPU) is prominently used for its elastomer-like behavior, suitable flexibility, and facility of combination with diverse conductive materials. These characteristics satisfy the growing demands for better stretchability, higher sensitivity, and a wider workable sensing range of flexible strain sensors. In this review paper, recent progress on TPU-based strain sensors is tracked and discussed, including carbonaceous entities, silver nanomaterials, and conductive polymers in terms of various conductive materials first. Afterward, exciting and effective designing of macro- and microstructures, as well as their influence on the performance of strain sensors, is discussed. Finally, TPU-based strain sensors' wide applications and distinctive multifunctionality are presented and reviewed. This review paper presents the profound significance and attractive prospects of TPU-based flexible strain sensors in the design and development of intelligent devices.