Enhancing the linear sensing range of elastic fabric wearable strain sensors with kirigami patterns

Abstract

Abstract Wearable stretchable sensors capable of monitoring real-time human movements and muscle engagement have broad sports, military, and healthcare applications. Their flexibility, lightweight nature, and seamless integration into textiles make them an ideal solution for capturing dynamic joint, limb, and body movements. Specifically, a self-adhesive, elastic fabric, wearable skin-strain sensor called Motion Tape, made by integrating carbon nanotubes (CNT) with kinesiology tape, was proposed. It was found that CNT Motion Tape exhibits linear strain sensitivity up to 2% strain but may not be suitable for measuring skin-strains associated with many large, dynamic movements. Therefore, the objective of this study was to enhance the linear strain sensing range of CNT Motion Tape by introducing Kirigami cut patterns to the textile substrate to intentionally modify its stress/strain distribution, thereby enhancing stretchability while releasing stress/strain concentrations in the vicinity of the nanocomposite sensing element. Different Kirigami designs were investigated, and electromechanical load frame and human subject tests were conducted to assess their strain sensing properties. The results showed that stress-releasing Kirigami designs could significantly increase the linear strain sensing range of CNT Motion Tape from ~2% to ~13%. Finite element modeling of Motion Tapes with Kirigami cuts further revealed how stresses/strains were relieved for validating the experimental results. Although this work focused on CNT Motion Tape, the results are translatable to other types of materials-based wearables.