Spray-Coated Ultrathin\nand Porous Films for Physiological\nSensing and Force Detection

Epidermal electronics employed on human skin for the\nlong term\nrequire good breathability and nonforeign wearing. In this work, we\ncombine phase separation and spray coating to fabricate a porous and\nultrathin electrode within minutes as well as micrometer-scale porous\npressure sensors. The resulting electrodes show a water vapor transmission\nrate of 18.4 mg·cm<sup>–2</sup>·h<sup>–1</sup>, sheet resistance of 5.2 Ω/sq, and thickness below 5 μm.\nThe introduction of the biogel further reduced the electrode–skin\nimpedance, which is lower than that of the commercial gel electrode,\nindicating that the electrode can have a high degree of conformal\ncontact with the skin. The epidermal electronics prepared by this\nstrategy exhibit an excellent performance in force sensing. Such results\nstrongly prove the efficiency and practicality of the strategy.