Herein, we report the fabrication as well as application of a multiwall carbon nanotube-reduced graphene oxide polyester band (MWNT-rGO@PEB) piezoresistive strain sensor for human-machine interface applications. The addition of unzipped functionalized MWNTs in the rGO ink assists in providing the propagation path for the charge carriers. The sensing mechanism involved for this strain sensor comprises two regimes, one with a gauge factor of 150 (0%-25%) and the other one with 650 (28%-40%) with the change in the resistivity at a low strain value since the fibres entangled together and wrapped with conductive rGO flakes get separated very slightly apart. At higher strain values, the flakes wrapped on the fibre backbones separated far apart, resulting in a disconnected percolation path for the charges. This kind of sensing mechanism has enough potential to detect small scale as well as large scale motions with excellent reproducibility over 2000 cycles. Some heath monitoring applications such as forearm motion, cheek bulging, and finger bending have been demonstrated in real time by using this piezoresistive strain sensor. The significant advantages of these sensors are their low cost, easy fabrication (one step), and versatility, which render them favourable for health-monitoring applications.
Tewari, A., Gandla, S., Bohm, S., McNeill, C. R., & Gupta, D. (2018). Rapid dip-dry MWNT-rGO ink wrapped polyester elastic band (PEB) for piezoresistive strain sensor applications. Applied Physics Letters, 113(8). https://doi.org/10.1063/1.5037318