Harvard engineers create knitted textiles that snap between stable shapes

At Harvard's John A. Paulson School of Engineering and Applied Sciences (SEAS), researchers have created machine-knitted fabrics capable of shifting between various stable three-dimensional shapes without the need for rigid elements. The project, spearheaded by Kausalya Mahadevan and in partnership with Katia Bertoldi's lab, utilized conventional industrial knitting machines to fabricate mechanical metamaterials using elastic yarns and plating methods. These textiles demonstrate multistability, curling into 3D forms and changing under stress. Featured in Advanced Functional Materials, the study reveals that weft knitting can achieve nonlinear mechanical properties usually obtained through molding or additive manufacturing. Incorporating conductive yarns allows these fabrics to serve as wearable sensors, such as a snapping shell functioning as an LED switch and knee/elbow patches that electronically track movement. This innovative method capitalizes on existing textile manufacturing processes, suggesting potential for scalable production of responsive fabrics in wearable technology, soft robotics, and adaptable interiors.