Crossed-Fiber Bimodal Sensor with Differentiated Resistive-Capacitive Responses for Localized Thermal-Touch Sensing

Abstract Integrating thermal and mechanical sensing into simple fiber platforms remains challenging because of cross-influence between sensing channels. Here, a fiber-shaped bimodal temperature-mechanical sensor is developed by combining a thermoresponsive SEBS/acrylate copolymer (AC)/carbon black (CB) conductive core with a silicone rubber dielectric shell and an orthogonally crossed-fiber architecture. The composite core provides a pronounced positive temperature coefficient (PTC) response, while deformation of the crossed junction enables capacitive force sensing. The sensor operates over 25–45 °C and 0.0025–0.98 N. Quantitative analysis shows that resistance is predominantly governed by temperature, whereas capacitance is influenced by both temperature and force. A temperature-dependent baseline correction improves force discrimination, although residual thermal-mechanical coupling remains. Repeated thermal and DSC cycling demonstrate reproducible sensing and phase-transition behavior. A localized thermal-touch demonstration further verifies simultaneous thermal and mechanical sensing, highlighting the potential of this compact fiber platform for textile-integrated thermal-touch applications.