Comparative study of the weft-knitted strain sensors

In this study, weft-knitted strain-sensing structures are described, along with the materials and manufacturing techniques required to produce the fabrics on a computerised flat-bed knitting machine. Knitted sensing fabrics with conductive yarns, i.e. silver-plated nylon yarn and polyester-blended stainless steel yarn have been created with different design possibilities. A laboratory test set-up was built to characterise the knitted sensors and the resulting equivalent resistance under the different level of strains. The most successful samples have been realised through a series of single conductive courses within the interlock base fabric structure using silver-plated nylon in terms of responsivity, repeatability and lower electrical signal drift. Deficiencies associated with strain-sensing structures realised through the intermeshing of conductive yarns have also been addressed.