Researchers at the University of Cambridge have pioneered a method to create adaptive and eco-friendly sensors that can be imperceptibly printed onto a variety of biological surfaces, from human skin to delicate flower petals. Inspired by the conforming and adhesive properties of spider silk, these sensors, referred to as “spider silks,” incorporate bioelectronics to provide versatile sensing capabilities.

The fibers, which are at least 50 times thinner than a human hair, are exceptionally lightweight. This allows them to be printed directly onto delicate structures like a dandelion seedhead without causing damage. When applied to human skin, the fiber sensors adapt to the skin’s surface and expose sweat pores, rendering them virtually undetectable to the wearer. Tests on human fingers indicate their potential use as continuous health monitors. This innovative, low-waste, and low-emission method for augmenting living structures could revolutionize fields such as healthcare, virtual reality, electronic textiles, and environmental monitoring. The findings are detailed in the journal Nature Electronics.

Despite the remarkable sensitivity of human skin, integrating it with electronic sensors could transform our interaction with the environment. For instance, sensors printed directly on the skin could enable continuous health monitoring, enhance our understanding of skin sensations, or elevate the realism in gaming and virtual reality applications.

Current wearable technologies with embedded sensors, like smartwatches, often prove uncomfortable and obtrusive, hindering the skin’s natural sensations. “If you want to accurately sense anything on a biological surface like skin or a leaf, the interface between the device and the surface is vital,” said Professor Yan Yan Shery Huang from Cambridge’s Department of Engineering, who led the research. “We also want bioelectronics that are completely imperceptible to the user, so they don’t in any way interfere with how the user interacts with the world, and we want them to be sustainable and low waste.”

Existing methods for making wearable sensors have significant limitations. Flexible electronics are typically printed on plastic films that block gas and moisture, akin to wrapping skin in plastic. Recent advances in gas-permeable flexible electronics, resembling artificial skins, still interfere with natural sensation and rely on energy- and waste-intensive manufacturing processes.

3D printing offers a less wasteful alternative for bioelectronics but results in thicker devices that can impede normal function. While spinning electronic fibers can produce imperceptible devices, they lack high sensitivity and sophistication and are challenging to transfer onto the target object.

The novel sensors developed by the Cambridge team promise to overcome these limitations, offering a sustainable, sensitive, and user-friendly solution for a wide range of applications.

By Impact Lab