Tuning the Poisson ratio of weft-knits: from folded architectures to sensing

We present a new class of weft-knit textiles that display auxetic behavior under strain due to their complex folded structure. By tuning the size of the unit cell and the width of individual folds, we can also tune the mechanical response—in particular the magnitude of the Poisson ratio and corresponding strain under tensile loading. We draw an analogy between existing auxetic patterns and the folded textile pattern in order to develop a model to predict the folded shape and mechanical response of the textile. By incorporating conductive areas, we show the potential of these textiles to create a family of strain sensors where the strain-capacitance relationship can be tuned through the Poisson ratio.