Researchers at the University of Tartu have found a way to turn embroidery from decoration into function. By strategically placing thread in certain patterns on elastic fabrics, they can program how much a textile stretches in specific areas, similar to how skin behaves under tension, reports Tech Xplore.
The technique uses zigzag stitches (called “fibrous springs”) made with inelastic polyester thread on elastic fabric. When the stitch is zigzagged, there is slack that lets the fabric stretch until the thread straightens. If the stitch is straight, it doesn’t stretch. By changing the zigzag amplitude, the researchers can control the amount of stretch allowed locally.
These stitches are arranged in a triangular mesh across the fabric. In such a mesh, each triangular unit, or spring, is looped and firmly knotted so that the stitch pattern won’t unravel. This gives precise control over local stretch behavior while maintaining structural integrity.
To make it workable in design and manufacturing, they created a workflow where designers can “paint” stretch properties using standard RGB channels in a digital image. That image then gets converted with a custom Python library into instructions for the embroidery machine. So areas in the fabric can be stiff, stretchy, or somewhere in between depending on the stitched pattern.
The resolution achieved is about 7 mm per unit spring, which is fine enough to mimic skin’s mechanics pretty well. As a demonstration, they made footwear from a single embroidered textile panel with over a thousand units and almost 20,000 stitches. The shoe conformed well to the wearer: tighter around the heel, avoiding slack, while allowing toe flexion without restriction.
Overall, this method promises mass customization of wearables: garments and items that adapt to the body’s shape and movements, offering better fit, comfort, and function without sacrificing scale. It bridges software design, embroidery machinery, and human biomechanics in a smart way.