Development of Mode-Switchable Touch Sensor Using MWCNT Composite Conductive Nonwoven Fabric.

Among the various wearable electronic devices, textile-based piezo sensors have emerged as the most attractive sensors for practical application. In this study, a conductive nonwoven fabric is fabricated to develop a textile-based piezo sensor. This high-performance fabric is fabricated by depositing multiwalled carbon nanotubes (MWCNTs) on cellulose nonwoven composites with carbon fibers (CNwCa) through a spray process to assign conductivity, followed by electrospinning thermoplastic polyurethane (TPU) on the MWCNT-coated CNwCa to improve surface durability. Each component is optimized through experiments to control the electrical and physical characteristics of the conductive nonwoven fabric. The static and dynamic piezoresistive properties of the fabricated MWCNT composite conductive nonwoven are measured using a source meter and the fabricated sensor driving circuitry. In addition, a prototype bag with a touch sensor is developed using the fabricated conductive nonwoven fabric and its touchpad function is demonstrated using an Android application. The operation as a mode-switchable touch sensor was experimentally verified by inserting the sensor into a bag so that it can be used without direct manipulation on a mobile device. The findings of this study suggest that the developed flexible textile-based conductive nonwoven fabric can be effectively used in wearable devices with piezoresistive sensors.