LAUSR

Conventional electronic (e‐) skins are a class of thin‐film electronics mainly fabricated in laboratories or factories, which is incapable of rapid and simple customization for personalized healthcare. Here a new class of e‐tattoos is introduced that can be directly implemented on the skin by facile one‐step coating with various designs at multi‐scale depending on the purpose of the user without a substrate. An e‐tattoo is realized by attaching Pt‐decorated carbon nanotubes on gallium‐based liquid‐metal particles (CMP) to impose intrinsic electrical conductivity and mechanical durability. Tuning the CMP suspension to have low‐zeta potential, excellent wettability, and high‐vapor pressure enables conformal and intimate assembly of particles directly on the skin in 10 s. Low‐cost, ease of preparation, on‐skin compatibility, and multifunctionality of CMP make it highly suitable for e‐tattoos. Demonstrations of electrical muscle stimulators, photothermal patches, motion artifact‐free electrophysiological sensors, and electrochemical biosensors validate the simplicity, versatility, and reliability of the e‐tattoo‐based approach in biomedical engineering.