It is believed that the development of the equipment could make biomedical or wearable technologies more comfortable for users by allowing sweat and other organic compounds to evaporate through it, away from the skin. The team’s research and findings are published on April 29 in ACS Nano magazine. The research describes how the material was created and how its electrode exhibits excellent stability in the presence of sweat and after prolonged use.
A “breakthrough” over other stretchable electronic devices
Yong Zhu, one of the correspondent authors of an article on the work, said that the gas permeability of the material is a “breakthrough over previous elastic electronics,” adding that what is just as important is the production method. of the material – a “simple process that would be easy to scale up.” According to NC State, the researchers used what is known as the “figure of breath” method, a method used to form porous films from templates of water droplets , to create a stretchable polymer film with an even hole distribution. Figures of breath are made up of microdroplets of water condensed on a cold surface of warm and humid air such as breath. The film is then coated by dipping it into a solution containing silver nanowires (AgNW). Finally, the material is heat pressed to seal the nanowires. The resulting film has a transmittance of 61%, a sheet resistance of 7.3 Ω / sq and a water vapor permeability of 23 mg cm – 2 h – 1, “… an excellent combination of electrical conductivity, optical transmittance and water vapor permeability,” Zhu said in a statement. “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 prolonged use.” The end result is an extremely thin film, of a few micrometers thick. The NC State team says this allows for better skin contact, resulting in a better signal-to-noise ratio for a more accurate reading and a low impedance of skin electrodes.
A case developed by researchers that incorporates electronic tissue. Image credited to Yong Zhu, University of North Carolina
Demonstrating the potential of the material
To demonstrate the material’s potential for use in wearable devices, the researchers developed two prototypes: skin-mountable biopotential sensing for healthcare and textile-integrated touch sensing for human-machine interfaces. The first prototype (for biological potential sensing ) consisted of dry, skin-mountable electrodes for use as electrophysiological sensors that could be used in the healthcare field for electrocardiography (ECG) and electromyography (EMG).
Extending the ruggedness of wearable sensors The second prototype (textile-integrated touch sensing) was permeable to gases and demonstrated the material’s potential for touch sensing for human-machine interfaces. As a proof of concept, the researchers used an integrated wearable textile sleeve with porous electrodes to play computer games. “If we want to develop wearable sensors or user interfaces that can be used for a significant period of time, we need gas-permeable electronic materials.” Zhu said. “So this is an important step forward.” The importance of gas permeability can be great for improving comfort, but its importance goes even further by avoiding irritation to the skin of those who wear it.
