The University of Cambridge researchers have created a method for producing adaptive and environmentally friendly sensors that can be printed directly onto various biological surfaces without being noticed. The inspiration for this method came from spider silk, which has the ability to conform to and stick to different surfaces.These ‘spider silks’ also have bioelectronic capabilities, allowing for the addition of various sensing abilities to the ‘web.’
The fibers are at least 50 times smaller than a human hair, making them so lightweight that researchers were able to print them directly onto the fluffy seedhead of a dandelion without affecting its structure. When printed on human skin, the fiber sensors conform to the skin and reveal the sweat pores, making the wearer unaware of their presence. Tests using the fibers printed onto a human finger suggest that they could be utilized as continuous health monitors.
This method of enhancing living structures is low-waste and low-emission, making it a promising development.The findings have been published in the journal Nature Electronics and have a wide range of potential applications, including healthcare, virtual reality, electronic textiles, and environmental monitoring. Human skin is incredibly sensitive, and adding electronic sensors to it could revolutionize the way we engage with our environment. For instance, sensors that are printed directly onto the skin could be used for ongoing health monitoring, understanding skin sensations, or enhancing the sense of ‘reality’ in gaming and virtual reality. This technology could also be integrated into wearable devices like smartwatches.While wearable sensors are now widely accessible, they can be uncomfortable, intrusive, and may impede the natural sensations of the skin.
Professor Yan Yan Shery Huang from Cambridge’s Department of Engineering, who spearheaded the study, stressed the importance of the interface between the device and the surface in accurately sensing anything on a biological surface like skin or a leaf. Additionally, the goal is to develop bioelectronics that are undetectable to the user and do not interfere with their interactions with the world. Moreover, the aim is to create sustainable and low-waste bioelectronics.
Various techniques exist for producing wearable sensors, but these are often not ideal for creating imperceptible and unobtrusive devices.The use of flexible electronics may have some disadvantages. For instance, these electronics are often created on plastic films that do not allow gas or moisture to pass through, making it similar to wrapping your skin in cling film. While some researchers have developed gas-permeable flexible electronics similar to artificial skins, they still disrupt normal sensation and require energy- and waste-intensive manufacturing techniques.
Another potential option for bioelectronics is 3D printing, which is considered to be less wasteful than other production methods. However, it can result in thicker devices that may interfere with normal behavior.The development of electronic fibres that are tiny and undetectable to the user has been a challenge due to the need for high sensitivity and sophistication. Additionally, transferring these devices onto a particular object has proven to be difficult. However, a team led by Cambridge has come up with a new approach to creating advanced bioelectronics that can be tailored to various biological surfaces, such as a fingertip or the feathery seedhead of a dandelion, by directly printing them onto the surface. Their method is partly inspired by spiders, which construct strong and intricate web structures suited to their environment using minimal material. This research offers promising possibilities for the future.Researchers developed bioelectronic ‘spider silk’ using PEDOT:PSS (a biocompatible conducting polymer), hyaluronic acid, and polyethylene oxide. The fibers were created at room temperature from a water-based solution, giving the researchers the ability to control the fibers’ ‘spinnability.’ An orbital spinning approach was designed to allow the fibers to conform to living surfaces, including microstructures such as fingerprints.
Testing of the bioelectronic fibers on various surfaces, such as human fingers and dandelion seedheads, demonstrated high-quality sensor performance while remaining undetectable.
“Our unique spinning method allows the bioelectronic fibers to conform to various shapes, both at a small and large scale, without the need for image recognition,” explained Andy Wang, the primary author of the paper. “This opens up new possibilities for creating sustainable electronics and sensors. It offers a much simpler way to produce sensors over a large area.”
Typically, high-resolution sensors are manufactured in a specialized cleanroom using toxic chemicals and a complex, energy-intensive process. The sensors developed at Cambridge, on the other hand, can be produced anywhere and require only a small amount of energy.The new bioelectronic fibres are more energy-efficient than traditional sensors, and they are also repairable. When they are no longer useful, they can be easily washed away, generating less than a single milligram of waste. In comparison, a typical load of laundry produces between 600 and 1500 milligrams of fibre waste. According to Huang, the sensors can be placed almost anywhere and repaired as needed without the use of a large printing machine or central manufacturing facility. They can be made on-demand, right at the location where they are needed.The researchers have developed devices that could have a wide range of applications, from health monitoring and virtual reality to precision agriculture and environmental monitoring. They believe that by incorporating other functional materials into their fiber printing method, they can create integrated fiber sensors that can enhance living systems with display, computation, and energy conversion functions. The research is being commercialized with the support of Cambridge Enterprise, the University’s commercialization arm. This research received support from the European Research Council, Wellcome, and the Royal S.ociety, and the Biotechnology and Biological Sciences Research Council (BBSRC), part of UK Research and Innovation (UKRI).
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