Ultrathin Hydrogel Films Toward Breathable Skin-Integrated Electronics

On-skin electronics that offer revolutionary capabilities in personalized diagnosis, therapeutics, and human-machine interfaces require seamless integration between the skin and electronics. A common question remains whether an ideal interface can be introduced to directly bridge thin-film electronics with the soft skin, allowing the skin to breathe freely and the skin-integrated electronics to function stably. Here we report an ever-thinnest hydrogel that is compliant to the glyphic lines and subtle minutiae on the skin without forming air gaps, produced by a facile cold-lamination method. The hydrogels exhibit high water-vapor permeability, allowing nearly unimpeded transepidermal water loss and free breathing of the skin underneath. We demonstrate hydrogel-interfaced flexible (opto)electronics without causing skin irritation or accelerated device performance deterioration. The long-term applicability was recorded for over one week. With combined features of extreme mechanical compliance, high permeability, and biocompatibility, the ultrathin hydrogel interface will promote the general applicability of skin-integrated electronics. This article is protected by copyright. All rights reserved.