Liquid metal E-tattoo

The past twenty years have witnessed a rapid advancement in medical devices and healthcare techniques. Motivated by the growing demand for personalized, preventive, predictive and participatory medicine, the on-skin portable healthcare system with fascinating merits has attracted great interest. Especially, the electronic tattoo (E-tattoo) that can form intimate contact and deform with the skin movement is regarded to play an important role in further healthcare monitoring and disease treatment. Endowed with the combination of fluidity and metallic properties, liquid metals (LMs) have become an emerging class of functional materials and are regarded as the ideal candidate for soft electronics. Here, we highlighted the key advantages of LM in E-tattoo, classified the LM based conductive inks, and summarized the important pattern technologies in fabrication of LM E-tattoo. The typical applications of healthcare detection and therapy were also discussed. Finally, outlooks were provided for future E-tattoo development.