Ultra-conformal skin electrodes with synergistically enhanced conductivity for long-time and low-motion artifact epidermal electrophysiology

Abstract

Accurate and imperceptible monitoring of electrophysiological signals is of primary importance for wearable healthcare. Stiff and bulky pregelled electrodes are now commonly used in clinical diagnosis, causing severe discomfort to users for long-time using as well as artifact signals in motion. Here, we report a ~100 nm ultra-thin dry epidermal electrode that is able to conformably adhere to skin and accurately measure electrophysiological signals. It showed low sheet resistance (~24 Ω/sq, 4142 S/cm), high transparency, and mechano-electrical stability. The enhanced optoelectronic performance was due to the synergistic effect between graphene and poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which induced a high degree of molecular ordering on PEDOT and charge transfer on graphene by strong π-π interaction. Together with ultra-thin nature, this dry epidermal electrode is able to accurately monitor electrophysiological signals such as facial skin and brain activity with low-motion artifact, enabling human-machine interfacing and long-time mental/physical health monitoring.

Skin bioelectronics towards long-term, continuous health monitoring

“…301 In comparison with the wet and semi-dry electrodes, dry electrodes that do not require conductive gels or electrolyte fluid, show some advantageous merits such as improved userfriendliness and time-saving pre-preparation setup for portable EEG recording. 302 Dry electrodes with various morphologies such as skin-conformal electrodes, 294,[303][304][305] ultrathin electronic tattoos, 48,306 flexible sponge electrodes, 307 elastomeric hair electrodes, 308 micro-pillar-structured electrodes, 171 and microneedle electrodes, 309 have been designed and developed for user-friendly and potential long-term EEG detecting. As for the skin-conformal and ultrathin tattoo electrodes, they are only suitable for non-hairy skin surfaces, such as the outer ear location, frontal region, and shaved scalp.…”

All‐Nanofiber‐Based Janus Epidermal Electrode with Directional Sweat Permeability for Artifact‐Free Biopotential Monitoring

“…Electrocardiogram (ECG) reveals the real-time variations in the electrical activity of the heart during each cardiac cycle, which has vital clinical significance in the diagnosis and prevention of various heart diseases. [8,47] The feasibility of using Janus textile electrodes for ECG detection was demonstrated. As shown in Figure 6c and Movie S5, Supporting Information, regular and repeatable ECG signals are collected by Janus textile electrodes and wirelessly transmitted to a mobile phone in real time after conformally attaching a pair of electrodes to the chest.…”

Skin-Inspired Hair–Epidermis–Dermis Hierarchical Structures for Electronic Skin Sensors with High Sensitivity over a Wide Linear Range

“…35 The magnified Raman spectra in Figure S9 show that the peak at 1436 cm −1 due to CC symmetrical stretching of the PEDOT:PSS chains blueshifts to 1430 cm −1 after the combination with rGO nanosheets, indicating strong π−π interactions between PEDOT:PSS and rGO. 36,37 This interaction cross-links rGO and PEDOT:PSS, increasing the electron mobility at the interfaces between PEDOT:PSS and rGO. The two characteristic peaks at 1357 and 1590 cm −1 are assigned to the disorderinduced D band and the graphitic G band of rGO, respectively.…”