E-textiles, particularly knitted resistive strain sensors, have been proposed for joint motion measurements. Although combining non-elastic conductive yarns with elastic non-conductive yarns improves sensor performance, the effects of knitting patterns and strategies for integrating sensors into garments remain underexplored. This paper addresses both by: (1) comparing the characteristics of plain weft-knitted resistive strain sensors made from conductive silver-coated yarn and Lycra-based elastic yarn across multiple patterns, and (2) evaluating three integration methods–hand-sewn attachment to finished garments, snap-button attachment, and direct in-garment knitting. We find that the plated knitting pattern with conductive material on the knit side and the elastic non-conductive yarn on the purl side achieves the best sensor characteristics, with a gauge factor of 14.616 during stretching and 13.300 during release. For joint angle estimation, we compare multi-layer perceptrons and a random forest under both static holds and continuous motion for all three integration methods. Performance degradation from resistance drift can be substantially mitigated through pre-processing, including linear detrending and predicting relative rather than absolute angles. However, models trained on one integration method show limited transferability to others, underscoring the need for method-specific calibration. This work provides practical guidance on the design, fabrication, integration and data processing of knitted strain sensors for joint motion measurement.
Comparative analysis of knitted resistive strain sensors in joint motion measurements
Yu Xiao

