Stretchable electronic technologies offer the potential to monitor the body over extended periods of time in unprecedented ways. The heart’s rhythms, flexion of joints, and other biomedical parameters can be tracked with high fidelity and continuously using devices that can conform to the body. While much of this has already been possible, and documented here at Medgadget, one major hurdle to usability has been the lack of “breathability” of the stretchable substrates into which the electronics are embedded.
Now, researchers at North Carolina State University have developed a breathable, stretchy, electronic material that lets gases, such as volatile organic compounds and sweat come through, thereby allowing it to be worn over the skin for many days.
The new material is made using a “breath figure method” that permits the creation of tiny holes throughout a polymer film. The film is then dipped in a silver nanowire solution and the coating is heat-pressed to stay permanently on the film.
“The resulting film shows an excellent combination of electric conductivity, optical transmittance and water-vapor permeability,” said Yong Zhu, co-corresponding author of the study appearing in ACS Nano. “And because the silver nanowires are embedded just below the surface of the polymer, the material also exhibits excellent stability in the presence of sweat and after long-term wear.”
To show off the applicability of the new technology, the research team created a wearable dry electrode device that can be used in electrocardiography (ECG) and electromyography (EMG) applications, as well as an arm-worn computer controller that can be used for long periods of time.
The first prototype consisted of skin-mountable, dry electrodes for use as electrophysiologic sensors. These have multiple potential applications, such as measuring ECG and EMG signals.
Here’s a short video showing the material being used as part of an interface with a computer in order to play Tetris:
