Printable Electronic Spider Silk Sensors for Human Skin

The innovative method of creating bioelectronic fibres for adaptive sensors is inspired by the remarkable properties of spider silk, known for its ability to conform and stick to various surfaces. These 'spider silks' are designed to incorporate bioelectronics, allowing for the addition of different sensing capabilities to create adaptive sensors.

The fibres, which are at least 50 times smaller than a human hair, are incredibly lightweight. Researchers successfully printed these fibres directly onto the fluffy seedhead of a dandelion without compromising its structure. When applied to human skin, the fibre sensors conform seamlessly and expose sweat pores, making them imperceptible to the wearer. Initial tests on human fingers suggest that these fibres could serve as effective continuous health monitors.

This groundbreaking low-waste and low-emission method of enhancing living structures has vast potential applications across various fields, including healthcare, virtual reality, electronic textiles, and environmental monitoring. The findings of this research have been published in the prestigious journal Nature Electronics.

Human skin, being highly sensitive, could undergo a significant transformation with the integration of electronic sensors. The direct printing of sensors onto the skin opens up possibilities for continuous health monitoring, understanding skin sensations, and enhancing the immersive experience in gaming or virtual reality applications.

Professor Yan Yan Shery Huang, leading the research at Cambridge’s Department of Engineering, emphasized the importance of creating bioelectronics that are imperceptible to users while being sustainable and low waste. The interface between the device and the surface, whether skin or leaf, plays a crucial role in accurately sensing information without interfering with the user's interaction with the environment.

Various methods exist for developing wearable sensors, each with its limitations. While flexible electronics are commonly printed on plastic films, they hinder gas and moisture exchange, akin to wrapping the skin in cling film. Other approaches, such as gas-permeable flexible electronics, still disrupt normal sensation and rely on energy-intensive manufacturing processes.

The researchers utilized PEDOT:PSS, hyaluronic acid, and polyethylene oxide to spin their bioelectronic 'spider silk' fibres. These high-performance fibres were produced from a water-based solution at room temperature, enabling precise control over their 'spinnability.' An orbital spinning approach was designed to allow the fibres to conform to living surfaces, including intricate microstructures like fingerprints.

Tests conducted on various surfaces, including human fingers and dandelion seedheads, demonstrated the exceptional sensor performance of the bioelectronic fibres while remaining imperceptible to the host. This innovative spinning approach enables the fibres to adapt to different shapes at both micro and macro scales without requiring image recognition.

The bioelectronic fibres, which are repairable, can be easily washed away at the end of their useful life, generating minimal waste. In contrast to traditional sensors that involve toxic chemicals and energy-intensive fabrication processes, the Cambridge-developed sensors are energy-efficient and environmentally friendly.

The potential applications of these bioelectronic fibres range from health monitoring and virtual reality to precision agriculture and environmental monitoring. Future developments may involve incorporating additional functional materials into the fibre printing method to create integrated fibre sensors with display, computation, and energy conversion capabilities. The commercialization of this research is underway with the support of Cambridge Enterprise.

Support for the research was provided by the European Research Council, Wellcome, the Royal Society, and the Biotechnology and Biological Sciences Research Council (BBSRC) under UK Research and Innovation (UKRI). The development of these adaptive and eco-friendly sensors represents a significant advancement in the field of bioelectronics, offering endless possibilities for enhancing human-machine interactions and environmental monitoring.