Strain sensing performance of conductive polyester knitted fabric and its application in body motion monitoring

The effect of PVA (polyvinyl alcohol) content in solution system on the structure and performance of conductive PET/PANI/PVA (polyester/polyaniline/PVA) composite yarns has been studied. Conductive knitted fabrics of 2+2 rib structure are then prepared by conductive composite yarns; the strain–resistance sensing performances of the conductive knitted fabrics and their application in body motion monitoring are studied. The results indicate that an appropriate amount of PVA could help the conductive PANI layer on the fiber surface to form a stable interpenetrating polymer network structure, and improve its structural uniformity and conductivity. When the mass ratio of PVA to aniline in the solution system is 5%, the conductivity of the PET/PANI/PVA composite yarn could reach 1.887 S/cm, which is about 40% higher than that without PVA. Similarly, it’s wash fastness and abrasion resistance are significantly higher than that without PVA. Under the action of stretch-recovery, the electrical resistance of the conductive knitted fabric is first increased, then decreased, again increased and decreased. The conductive fabric shows a good sensing linearity when the resistance dropped or increased monotonously. In the process of cyclic tension, the resistance of the fabric increases and then tends to be stable. The fabric has good sensing repeatability after dozens of stretching cycles, and the addition of PVA in the conductive yarn is beneficial for the conductive fabric to obtain better sensing repeatability. The conductive knitted fabric has good sensitivity, with its gauge factor reaching up to 126.99. The strain sensor based on the conductive PET/PANI/PVA knitted fabric can be used to monitor real-time movement of a human body.