Researchers have developed a way to create adaptive, environmentally friendly sensors that can be printed directly and invisibly on a variety of biological surfaces, including fingers and flower petals. Credit: University of Cambridge
Cambridge researchers have developed a lightweight, environmentally friendly sensor inspired by spider silk that can be seamlessly integrated with biological surfaces for a range of applications in health monitoring and virtual reality.
Scientists have developed a way to create adaptive, environmentally friendly sensors that can be printed directly and invisibly on a variety of biological surfaces, including fingers and flower petals.
The method, developed by researchers at Cambridge University, is inspired by spider silk, which can adapt and stick to a variety of surfaces. This “spider silk” also incorporates bioelectronics, allowing the “spider web” to have a variety of sensing capabilities.
Advanced Sensor Technology
The fibers are at least 50 times thinner than a human hair and so lightweight that researchers could print them directly onto the fluffy seed heads of dandelions without them losing their structure. When printed on human skin, the fiber sensors conform to the skin and expose sweat glands, making the wearer unaware of their presence. Tests of the fibers printed on human fingers suggest they could be used as continuous health monitors.
This low-waste, low-emission method of biostructure augmentation could potentially be used in a variety of fields, from medicine and virtual reality to electronic textiles and environmental monitoring. The results were published today (May 24) in the journal Cell. Nature Electronics.
Researchers have developed an adaptable, environmentally friendly way to make sensors that can be printed unobtrusively directly on a variety of biological surfaces, including fingers and flower petals. The fibres are at least 50 times thinner than a human hair and so lightweight that the researchers were able to print them directly on the fluffy dandelion seed heads without disrupting their structure. Photo credit: University of Cambridge
Human skin is incredibly sensitive, but augmenting it with electronic sensors could fundamentally change the way we interact with the world around us. For example, sensors printed directly on the skin could be used to continuously monitor health, understand cutaneous sensations, or improve the sense of “reality” in games and virtual reality applications.
Challenges of Wearable Technology
Wearable technology with embedded sensors, such as smartwatches, is widespread, but these devices can be uncomfortable, intrusive and may interfere with the skin's natural sensations.
“If we want to accurately sense what is on a biological surface, like skin or a leaf, the interface between the device and the surface is crucial,” said Yanyan Sherry Huang, professor at Cambridge University's School of Engineering, who led the research. “We also want bioelectronics to be completely invisible to the user, as that would in no way interfere with the way the user interacts with the outside world, and would be sustainable and produce less waste.”
Researchers have developed a way to create adaptive, environmentally friendly sensors that can be printed directly and invisibly on a variety of biological surfaces, including fingers and flower petals. When printed on human skin, the textile sensor fits against the skin and exposes sweat glands, making the wearer unaware of its presence. Tests of the textile printed on a human finger suggest it could be used as a continuous health monitor. Credit: University of Cambridge
Innovation in flexible electronics
There are multiple ways to make wearable sensors, but they all have drawbacks. For example, flexible electronics are typically printed on plastic film that is impermeable to gases and moisture, making it akin to wrapping plastic wrap around the skin. Other researchers have recently developed flexible electronics that can pass gases, like artificial skin, but they still interfere with normal senses and rely on energy- and waste-intensive manufacturing techniques.
3D printing is another possibility for bioelectronics, as it produces less waste than other manufacturing methods, but it can make devices thicker and interfere with normal operation. Spinning electronic fibers creates devices that are imperceptible to the user, but are not as sensitive or sophisticated and difficult to transfer to a target object.
Now, a team led by the University of Cambridge has developed a new way to print high-performance bioelectronics directly onto a range of biological surfaces, from fingertips to the fluffy seed heads of dandelions. The technique is inspired in part by spiders, who use minimal material to create sophisticated, strong web structures that are adapted to their environment.
The researchers spun bioelectronic “spider silk” from PEDOT:PSS (a biocompatible conductive polymer), hyaluronic acid, and polystyrene. acidThe researchers then designed an orbital spinning approach that allowed the fibers to be transformed into biological surfaces, even into microstructures such as fingerprints.
Testing of the bioelectronic textile on surfaces such as a human finger and a dandelion seed head showed that it exhibited high-quality sensor performance while remaining undetectable by the host.
“Our spinning approach allows bioelectronic fibers to conform to anatomical structures of various shapes at both micro- and macro-scales without the need for image recognition,” said Andy Wang, first author of the paper. “It opens up a whole different angle on how we can make sustainable electronics and sensors. It's a much easier way to produce large-area sensors.”
Future Directions and Commercialization
Most high-resolution sensors are made in industrial clean rooms, requiring toxic chemicals in a multi-step, energy-intensive manufacturing process. The sensor developed by Cambridge can be made anywhere and uses only a tiny fraction of the energy needed for a regular sensor.
At the end of their useful life, repairable bio-electronic textiles can be easily washed away, generating less than one milligram of waste. By comparison, a single regular wash produces between 600 and 1500 milligrams of textile waste.
“Using our simple manufacturing technology, sensors can be placed almost anywhere and repaired when and where they are needed, without the need for large printing presses or centralized manufacturing facilities,” Huang said. “These sensors can be manufactured on demand, where they are needed, with minimal waste and emissions.”
The researchers say the device could be used for a variety of applications, from health monitoring and virtual reality to precision agriculture and environmental monitoring. In future, this fibre printing method could potentially incorporate other functional materials to build integrated fibre sensors to augment biological systems with display, computation and energy conversion capabilities. The research is being commercialised with the support of Cambridge Enterprise, the university's commercialisation arm.
Reference: “Imperceptible Augmentation of Living Systems with Organic Bioelectronic Textiles” by Wenyu Wang, Yifei Pan, Yuan Shui, Tawfique Hasan, Iek Man Lei, Stanley Gong Sheng Ka, Thierry Savin, Santiago Velasco-Bosom, Yang Cao, Susannah BP McLaren, Yuze Cao, Fengzhu Xiong, George G. Malliaras, Yan Yan Sherry Huang, May 24, 2024 Nature Electronics.
Publication date: 10.1038/s41928-024-01174-4
This research was supported in part by the European Research Council, Wellcome, the Royal Society and the Biotechnology and Biological Sciences Research Council (BBSRC), part of UK Research and Innovation (UKRI).
