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.

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Wearable devices are an indispensable part of modern life, and flexible capacitive pressure sensors as their luminous subset have assumed a significant role in this day and age owing to ultralow power consumption. In recent years, a fierce debate as well as numerous studies have been conducted to improve the sensitivity of capacitive pressure sensors, but a vital challenge of the mass production of a highly sensitive sensor by a low-cost method still remains. In this paper, to meet industrial demands, we propose a simple method to fabricate sandwich-structured capacitive pressure sensors on an industrial scale and at low cost; as the electrospinning collector, stainless steel screens with regular patterns and structures were utilized to gain the dielectric with both external microstructure and internal pores (dual structure). The prepared pressure sensor is composed of a thermoplastic-urethane electrospun nanofiber film, as a dielectric, in the middle and two conductive woven fabrics on the upper and lower sides as electrodes. Benefiting from the prolific air in the dielectric layer, the designed sensor demonstrates outstanding sensing performance, such as high sensitivity (0.28 kPa–1) in the low-pressure region (0–2 kPa), fast response/relaxation time (65/78 ms), and high-grade durability (1000 cycles). Moreover, the produced pressure sensor is employed for not only detecting human limb movements and object grasping but also detecting pressure distribution in sensor array state, so demonstrating the application potential in attachable wearable electronics.

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