Preliminary Results on Sensing Pillow to Monitor Head Movement using strain sensing threads

Threads have recently emerged as flexible and stretchable one-dimensional substrate for flexible bioelectronics, which can be easily integrated into existing textiles, like pillows, to impart them with sensing capabilities. In this paper, we integrate strain sensing threads made from 64% polyester, 36% polyurethane threads functionalized with a carbon conductive coating, and protected using a polydimethylsiloxane (PDMS) layer. They are then sewn into a memory foam pillow. The coating on the threads imparts durability, which allows the smart threads to endure exposure to moisture from sweating or washing. For 50% strain, the smart threads exhibit a gauge factor of around 2.5. It exhibits linearity for applied weight from 50.0-5000.0g with thread resistance ranging 0.5-20.0MΩ. The smart threads are connected to a resistance readout circuitry and wireless module to record and transmit strain information wirelessly to a computer. Preliminary results confirm the functionality and demonstrate real-time head motion tracking using the smart pillow.