attentions in modern biomedical researches. Skin-attachable devices based on on-skin electrodes enable the realtime monitoring of electrophysiological parameters (e.g., electrocardiography (ECG), electromyography (EMG), electroencephalogram (EEG), and electrical impedance tomography) that are of vital importance in medical diagnosis, rehabilitation training and treatment for chronic diseases. [1][2][3][4][5] These on-skin electrodes realize the transduction between electrical and ionic signals, and the electrophysiological measurement may indicate misleading artifacts if the electrode concepts are improperly designed. [6,7] To achieve accurate and long-term measurement, the electrodes are generally required to be attached on skin for a while. Therefore, electrodes are highly demanded to be lessirritating, biocompatible and stable. [8][9][10][11] Besides, to address motion artifacts, gelled electrodes are attached on skin with the assistance of adhesives, which may lead to skin injury during peeling off. The ideal electrode should be provided with the following characteristics: excellent biocompatibility, conformal attachment, user-friendliness, long-term stability, and low skin-electrode impedance to guarantee signal sensitivity and reliability. [12][13][14][15][16] Innovations in materials and structures of on-skin electrodes in recent years provide new insights into skin-electrode interfaces and opportunities for future flexible electronics. To eliminate motion artifacts, an ultrathin electrode (less than 5 µm) with excellent skin conformability was generally adopted. [17] In addition, bioinspired adhesive microstructures like octopusinspired microsucker, [18] gecko feet-like micropillars, [19] and beetle feet-similar micropads [20] allow firm attachment between electrode and skin. To address allergic issues, biocompatible materials such as Au nanomaterials, [21] breathable structures like substrate-free metal nanomesh [22] and porous substrate [8] were generally considered. Recently, to overcome interfacial issues caused by excessive sebum secretions, an anti-lipid electrode was developed using a surface amphiphilic modification technology, which removed epidermal lipids by simple water rinsing. [23] Although plenty of progresses have been achieved regarding skin-electrode interfacial issues, the sweating-related challenges have not yet been fully figured out. Sweating or perspiration is a form of thermoregulation, the daily water loss Recent technological innovations in wearable electronics offer possibilities to perform real-time monitoring of electrophysiological parameters, such as ECG, EMG, and EEG. To achieve accurate and long-term electrophysiological measurement, great signs of progress have been made in the skin-electrode interfacial problems; nevertheless, the challenges related to sweat have not been fully resolved. Excessive sweat between human skin and the electrode usually fails to achieve a conformal and intact contact, and the nonconductive barriers will lead to a high skin-electrode impedance....
