Fig. 5: liquid metal E-tattoo on human skin as wireless conformal heater and conformal flexible circuits and sensors.

a Wax is used to construct a raised structure on the surface of the silicone prosthesis, which simulates the structure of human skin lesions. b The LMPM is transferred to the "lesion site" to achieve conformal coverage of this structure. c, d LMPM transferred to the joints of human skin, which can be completely removed after a one-minute soap washing step, leaving the skin clean without residue. e Non-contact heating of conformal LMPM is achieved using a commercial high-frequency low voltage induction heater. The temperature is controlled by controlling the time and distance between the induction coil and the film. f Infrared image of the prosthetic skin after ten seconds of heating. (g)The contrast of height and temperature where the lesion is located. Corresponding to the position of the black dotted line in Fig. 5b and the position of the blue dotted line in Fig. 5f, respectively. h, i The conformal liquid metal circuit located on the back of the finger. j The conformal strain sensor on the back of the thumb. k The conformal strain sensor on the leaf of epipremnum aureum. l The curve of strain sensor’s resistance versus time. The strain sensor is located at the back of thumb which makes the flexing-stretching motion. m The resistance change of strain sensor during leaf growth. The plants were in the shade for the first ten days, and were exposed to sunlight or artificial light for the next ten days.