University of Tokyo’s Department of Electrical Engineering and Information Systems has developed ‘wearable tattoos’ which are inflammation-free, gas-permeable, lightweight, stretchable on-skin electronics with nanomeshes. According to the researchers, tattoos are so far meant for aesthetic look but now one can get a tattoo that can also act as a sensor that might save ones life by providing life-saving health data. The researchers are working on a super-stretchy wearable that feels like a second skin and can record data. The scientists say that thin-film electronic devices can be integrated with skin for health monitoring and/or for interfacing with machines. Minimal invasiveness is highly desirable when applying wearable electronics directly onto human skin. However, manufacturing such on-skin electronics on planar substrates results in limited gas permeability. Thus, it is necessary to systematically investigate their long-term physiological and psychological effects. As a demonstration of substrate-free electronics, the scientists showed the successful fabrication of inflammation-free, highly gas-permeable, ultrathin, lightweight and stretchable sensors that can be directly laminated onto human skin for long periods of time, realized with a conductive nanomesh structure. A week-long skin patch test revealed that the risk of inflammation caused by on-skin sensors can be significantly suppressed by using the nanomesh sensors. A wireless system that can detect touch, temperature and pressure is successfully demonstrated using a nanomesh with excellent mechanical durability.