Wearable electrodes are critical medical components for detecting abnormal electrical signals linked to health issues, such as heart attacks or neuromuscular diseases. However, the rigid nature of these devices can undermine their conformity to skin, reducing signal quality. A new development from Washington University in St. Louis offers a low-cost soft electrode that better conforms to the skin and delivers an improved signal-to-noise ratio (SNR).

The key to the conformable electrode design is the commercially available sugar cube, which is molded into the shape of the desired electrode and immersed in liquid polydimethylsiloxane (PDMS). The liquid is absorbed in about two hours, filling the spaces between sugar grains. A three-hour curing process then converts the liquid polymer into an elastic solid, and hot water is applied to dissolve the sugar to yield a spongy, porous matrix of PDMS. After being treated with oxygen plasma and ethylene glycol, the sponge is dipped in an electrically conductive polymer that forms into a thin film that coats the micropores.

Tests with human subjects confirmed that the sponge-like device performed as well as, or better than, a conventional electrode. The ability of the device to conform and adhere to the skin was superior to that of conventional rigid metal electrodes, and the reduced contact impedance resulted in high-quality electrocardiogram and electromyogram recordings with improved SNR.

The low-cost sponge electrode described in ACS Nano offers a promising platform for long-term wearable health monitoring applications.

To contact the author of this article, email shimmelstein@globalspec.com