From sewing thread to sensor: Nylon® fiber strain and pressure sensors

[Display omitted] •Devised a method of durably coating reduced graphene oxide (rGO) on intricate fibers of Nylon® fabric uniformly.•Carried out detailed morphological studies of fibers and fabrics using Scanning Electron Microscopy (SEM).•Carried out durability studies of the rGO coating on the Nylon® fibers by twisting the fibers in situ in SEM.•Studied the pressure/strain sensing capability of both rGO coated Nylon® fabrics and quarantined fibers.•Studied the capability of rGO-coated fibers to sense applied force and position simultaneously. Some of the most advanced laptop computers have their trackpads made to detect both force and position precisely. These trackpads are made of intricately designed force sensors, taptic engines and capacitive glass surfaces. In this study, we have modified simple Nylon® fabric which senses both force and position. A commercially available Nylon® fabric was coated with reduced graphene (rGO) in a layer by layer fashion such that the individual fibers of the fabric get wrapped by rGO and the fabric looks like dyed with grey color. The SEM images of the twisted individual rGO coated fibers show that the coating remains undamaged until a twist angle of about 1800°. An in situ applied pressure in compression, on the fabric, of about 2500kPa changes its resistance 8kΩ relative to its original resistance with a durability of up to 6000 cycles. Single rGO coated fibers quarantined and tested for their strain sensitivity show that an in situ bending radius of 1mm changes its resistance to 326±21kΩ relative to its original resistance. With the help of a read-out circuit it was also showed that quarantined rGO coated fibers arranged in a 2×2 grid format sense the position of the applied force.