A Direct Ink Writing Based Fabric-Embedded Soft Sensor for Improved Durability and Sewability

Abstract Soft sensors made of silicone and liquid metal have been used in wearable systems because they do not interfere the natural motion of users due to the remarkable elasticity. The soft sensors are usually used as wearable systems by being attached to fabric with adhesive, but the attached sensor can be easily delaminated from the fabric upon repeated stretching, which leads the limited range of use. Also, it was not easy to make complicated wearable systems with the fabric-attached soft sensor due to the bad sewability. In this paper, a new method is proposed for fabricating fabric-embedded soft sensors with improved durability and sewability. In the proposed method, the fabric is embedded by blade coating, and liquid metal wires are formed by direct ink writing (DIW), which enables inexpensive and fast design modification and an automated manufacturing procedure. The fabric-embedded soft sensor is more resistant to delamination than the fabric-attached soft sensor, which was experimentally verified. The tear resistance of the soft sensor improved by the embedded fabric was also experimentally verified. Based on the improved tear resistance, the fabric-embedded soft sensor could be easily sewn, which was also confirmed by experiments. As an application, a wearable wrist angle measurement system was developed by directly sewing the fabric-embedded soft sensors.