Multistable self-folding knit architectures for soft switches

Multistability – the property of having multiple stable equilibrium configurations – has recently emerged as a powerful platform to design a wide range of smart structures, including logic gates, transformable architectures and energy absorbing systems. In thin composite shells, conflicting stresses between layers provide a robust way to encode bistability. However, this typically requires the tedious assembly of layers while they are under strain. Here, we show that the weft knitting process intrinsically introduces differential internal stresses into the fabric and we exploit these stresses in periodic and non-periodic patterns to achieve multistability.

We then harness the snap-through behavior associated with multistability to design soft switches with built-in haptic feedback. These structures can then be incorporated into smart garments as an input mechanism that does not require bulky or energy-intensive external actuation to provide haptic feedback to a user.