A conformable, durable, adhesive welded fiber mate for on-skin strain sensing

On-skin electronics have been attracting tremendous attentions due to their potential use for continuous, long-term physical movement detection and physiological signal monitoring. However, developing on-skin strain sensors that can be conformally attached to skin with good breathability and adhesion remains a challenge. Here, we present an ultrathin, lightweight, breathable welded fiber mate-based strain sensor that can be conformally adhered to curved human skin through a sacrificial interlayer. The modulus of the fiber mate is similar to human skin, and its thinness and softness lead to minimum mechanical constraints on skin during deformation (0.03 N at 5 % strain). The welded mate sensor exhibits large stretchability (420 %) and sensing durability due to its double-level elastic structure on both polymer chain and fiber chain levels. It can work over a wide temperature range from 0 to 40 °C with almost no temperature interference. After patterned into a serpentine geometry, the welded mate can also be used as a stretchable and conformal gas sensor to detect harmful gases with excellent stability against strain interference.