At the University of Illinois Urbana-Champaign Materials Research Laboratory, YuHao Liu has tested tiny sensors on human volunteers and published promising results. “For skin-mounted tattoo sensors, users would not feel them, as their thickness and weight are comparable to human skin,” Liu told The Daily Beast via email. Liu said one big advantage is that most experimental sensors are so light that volunteers do not feel them, unlike their heavier counterparts.

Liu is a leading “Lab-on-Skin” researcher, and is developing the tattoos that resemble human skin in thickness. The device’s name underscores that wearers will be carrying a mini-laboratory on their skin.

The Lab-on-Skin devices being tested can fit inside a human ear and conform closely to a wearer’s body. This can decrease the errors common in rigid electronics that cannot bend easily to follow ever-stirring muscles.