Highly Robust, Transparent, and Breathable Epidermal Electrode

Abstract

Recently emerged electronic skins with applications in on-body sensing and human-machine interfaces call for the development of high-performance skin-like electrodes. In this work, we report a highly robust, transparent, and breathable epidermal electrode composed of a scaffold-reinforced conductive nanonetwork (SRCN). Solution-dispersed Ag nanowires, through facile vacuum filtration, are embedded into a scaffold made of polyamide nanofibers. Optical transmittance of 84.9% at 550 nm wavelength is achieved at a significantly low sheet resistance of 8.2 Ω sq. The resistance of the SRCN only slightly increases by less than 0.1% after being bent for 3000 cycles at the maximum curvature of 300 m and by less than 1.5% after being dipped in saline solution for 2500 cycles. The excellent robustness is attributed to the reinforcement from the nanofiber-based scaffold as a backbone that maintains the connections among the Ag nanowires by undertaking most of the loaded stress. The SRCN not only forms tight and conformal bonding with the target surface but also allows the evaporation of perspiration, making it suitable as an epidermal electrode for long-time use. Furthermore, fine and clean-cut circuit patterns with a line width on the micrometer scale can be readily prepared, paving the way for fabricating sophisticated functional electronic skins.

Nanofiber‐Reinforced Silver Nanowires Network as a Robust, Ultrathin, and Conformable Epidermal Electrode for Ambulatory Monitoring of Physiological Signals

“…This is presumably because the nanofibers/nanowires structure becomes more compact at the initial stage, which results in more interconnected junctions among the AgNWs. Similar observations have been previously reported for other AgNWs‐based electrodes . The excellent mechanical robustness of the NEE is likely attributed to the reinforcement provided by the nanofiber‐based scaffold .…”

“…Similar observations have been previously reported for other AgNWs‐based electrodes . The excellent mechanical robustness of the NEE is likely attributed to the reinforcement provided by the nanofiber‐based scaffold . The scaffold undertakes most stress during the deformation, while little stress is loaded onto the AgNWs because they are subject to displacement within the scaffold.…”

“…For the NEE with a thickness of 125 nm, a low sheet resistance of 4.14 Ω sq −1 with an optical transmittance of 82.3% at a wavelength of 550 nm was achieved. Attributed to the nanofiber‐based scaffold that undertakes most of the stress during deformation, the NEE exhibited superb mechanical stability. The electric resistance increased by merely 1.2% after 50 000 bending cycles at a curvature of 360 m −1 .…”

Breathable Nanowood Biofilms as Guiding Layer for Green On‐Skin Electronics

“…On‐skinE must have adequate cross‐plane breathability. In fact, the demand for skin health (allowing skin metabolism and reducing anaerobic bacteria) and sensitive biosensing has spurred works directed at designing “breathable” device structures and constructing electronics on “breathable” substrates (e.g., microperforated plastic films, nanofiber films, and textiles) as the plastic films currently used in WearE are air‐tight in nature, with low water vapor transmission rates (WVTRs < 50 g m −2 day −1 ) …”

Skin‐Friendly Electronics for Acquiring Human Physiological Signatures

“…The innovative combination of silk and resilin proteins retains the desirable intrinsic properties of high biocompatibility, high flexibility, high skin adhesion, low stiffness, and exceptional resilience. [15,16] The two sensors were based on a regenerated edge-decorated graphene (R-EDG) sheet that contained both an easily functionalized edge area and a highly conductive central area. [15,16] The two sensors were based on a regenerated edge-decorated graphene (R-EDG) sheet that contained both an easily functionalized edge area and a highly conductive central area.…”