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There is generally a stigma attached to wearable technology – even something as ubiquitous as eyeglasses, and moreso if it involves medical monitoring. Now, researchers at Tufts University, a private research institution based in Massachusetts, have created a wearable technology that’s so thin, light, flexible, and unobtrusive that users will barely notice they’re wearing it. While around 33 percent of Americans wear smart rings and smart watches, which can function as medical monitors, the Tufts breakthrough is in smart, electronic threads.
In a paper published recently in Applied Materials and Interfaces, Prof. Sameer Sonkusale and colleagues describe devising the complex integrated circuits of “thread-ectronics” from sensors, transistors and other components. To prove the effectiveness of thread-ectronic sensors, the team demonstrated how their innovation amplified subtle signals that could, in context, indicate stress, illness and more. For instance, by using a sensor attached to one’s temple they could detect blinking, and by using a sensor on the thorax they could detect changes in respiration.
By their flexible design, these thread-ectronics also allow coiling, stretching and bending without breaking. Designers could easily add them into any clothing, including athletic and workwear for activities usually incompatible with protecting delicate body monitors. The e-thread could even be applied directly to the skin for transmitting environmental or somatic telemetry for improving healing, health, or athletic performance.
“By moving electronics from planar patches to free-form threads,” said Sonkusale, “we have opened a path toward wearable bioelectronics that are more like fibers than hardware.”
The new med-tech will move naturally with the human body rather than forcing humans to adapt their movement to it, which rigid and fragile monitoring devices required. In fact, he says, “It could potentially be used like sutures to monitor processes inside the body,” as well as monitoring breathing in adults and infants, assessing fall risks, and generating movement profiles for identifying physical and cognitive decline.
To function, thread-ectronics contain flexible micro-transistors attached to gold-coated filaments. These transistors are composed partly from a plastic-like conductor connecting the gold-coated filaments entering and exiting them, allowing them to function like faucets for electrons.
The thread-ectronics also rely on eutectogels, which create a sub-millimeter gap between the thread-ends to control the flow of electrons via resistors, capacitors, or other components. While severing thread-ectronics will destroy them, eutectogels are stable, soft enough to touch or connect to the human body, and can allow transistor repair through the simple application of low heat.
Furthermore, creating it doesn’t require delicate photolithography that is standard in building integrated circuits, nor high-temperature processing or clean rooms. Because manufacturing the product works well with textile-style materials and soft polymers, future production should be low-cost.
As lead author and Tufts electrical engineering Ph.D. candidate Wenxin Zeng says, “The technology platform is still in early stages … we expect to improve the speed and precision of fabrication, and the ability of the thread-based integrated circuits to carry out more complex functions.”