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This paper summarises preliminary work comparing conductive yarns, knitting structures and yarn compositions in order to integrate smart sensor strips into a surrounding garment as a kinematic measurement tool. The conductive areas of the garment were to be used as a strain-sensitive material; ultimately measuring knee joint movement. In total, thirty sample fabrics were developed using conductive yarns; six of which were chosen to be tested for responsiveness during repeated strain. Preliminary tests showed good levels of responsiveness to strain and acceptable levels of recovery.

The objective of this study was to measure the combined effects of fiber type (fine wool, mid-micron wool, acrylic), yarn type (high twist, low twist, single) and fabric structure (single jersey, half-terry, terry) on friction between sock fabrics and a synthetic skin using the horizontal platform method. The effect of weight of a hypothetical wearer and moisture content of a sock fabric were also investigated. Differences among fabrics were analyzed using frictional force traces. Data compared included the static and dynamic friction and coefficients of friction, as well as three new descriptive parameters. All variables investigated affected the frictional characteristics between a sock fabric and a synthetic skin. Single jersey fabrics had the lowest coefficient of static and dynamic friction. Friction between fabric and a synthetic skin was affected most by the applied weight, with the simulated adult weight resulting in a greater frictional force, and higher coefficients of static and dynamic friction. The most important effect of fiber was on the static frictional force and coefficient of static friction of damp fabrics, with fabrics composed of fine wool exhibiting lowest friction, and acrylic fabrics the highest.

This study demonstrates a scalable fabrication process for producing biodegradable, highly stretchable and wearable melt spun thermoplastic polypropylene (PP), poly(lactic) acid (PLA), and composite (PP:PLA = 50:50) conductive yarns through a dip coating process. Polydopamine (PDA) treated and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coated conductive PP, PLA, and PP/PLA yarns generated electric conductivity of 0.75 S/cm, 0.36 S/cm and 0.67 S/cm respectively. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the interactions among the functional groups of PP, PLA, PP/PLA, PDA, and PEDOT:PSS. The surface morphology of thermoplastic yarns was characterized by optical microscope and Scanning Electron Microscope (SEM). The mechanical properties of yarns were also assessed, which include tensile strength (TS), Young’s modulus and elongation at break (%). These highly stretchable and flexible conductive PP, PLA, and PP/PLA yarns showed elasticity of 667%, 121% and 315% respectively. The thermal behavior of yarns was evaluated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Wash stability of conductive yarns was also measured. Furthermore, ageing effect was determined to predict the shelf life of the conductive yarns. We believe that these highly stretchable and flexible PEDOT:PSS coated conductive PP, PLA, and PP/PLA composite yarns fabricated by this process can be integrated into textiles for strain sensing to monitor the tiny movement of human motion.