A Review on Knitted Flexible Strain Sensors for Human Activity Monitoring

Abstract

The recent surge in using wearable personalized devices has made it increasingly important to flexible textile‐based sensors that can be worn comfortably and can sense various body strains. Among them, the knit‐based flexible strain sensors (KFSS) show growing promise for human activity monitoring applications due to its processing flexibility, low cost, wearing comfortability, large strain performance, and high elastic recovery rate. Herein, five sensing mechanisms of knitted flexible strain sensors containing contact resistance, length resistance, tunneling effect, micro‐crack propagation, and disconnection mechanism are summarized, which can be used on different human activity strain conditions, e.g., physiological activities and limb activities. The main fabrication approaches, including knitting techniques, post‐processing techniques, embroidery, and sewing techniques are discussed. Six crucial parameters with corresponding calculation formulas for evaluating sensing performance and review specific applications of KFSS for human limb activity and physiological activity monitoring in healthcare, motion tracking, safety protection, and human–machine interaction are also described. Finally, the tough challenges and prospects of KFSS with the aim of providing meaningful guidance and direction for future research are critically analyzed.

Highly Stretchable and Multimodal MXene/CNTs/TPU Flexible Resistive Sensor with Hierarchical Structure Inspired by Annual Ring for Hand Rehabilitation

“…), ionic liquids, and other materials are gradually beginning to be selected in the preparation of flexible wearable resistive sensors. However, it is a common problem that the conductive network constructed by one type of conductive filler is difficult to achieve both sensing range and stability concurrently due to microcrack expansion or disconnection mechanism . The current research trend is to combine two or more types of conductive materials with different dimensions to construct more stable multidimensional sensing networks.…”

“…However, it is a common problem that the conductive network constructed by one type of conductive filler is difficult to achieve both sensing range and stability concurrently due to microcrack expansion or disconnection mechanism. 36 The current research trend is to combine two or more types of conductive materials with different dimensions to construct more stable multidimensional sensing networks. For example, Dong et al 37 deposited 1D CNTs and 2D MXene on a TPU composite film, constituting a brittle densely stacked MXene upper lamella and a flexible MXene/CNT-decorated fibrous network lower layer.…”

Lithographically patternable SU-8/Graphene nanocomposite based strain sensors for soft-MEMS applications

“…The rise of the Internet of Things (IoT) has marked a new era of comprehensive sensing, offering precision data generation with unmatched sensitivity. Technological progress unlocks possibilities across consumer electronics [1], human healthcare [2], structural monitoring [3], transportation [4], defense [5], surveillance [6], and research fields, such as fuel exploration [7]. Smart and pervasive sensing integration in these areas has the power to transform how we experience and engage with the world, with the potential * Author to whom any correspondence should be addressed.…”