Figure 1: e-TLC thermal imaging device as an example of an epidermal photonic system.

(a) Picture of a device on the skin deformed by pinching in a twisting motion. Scale bar, 3 cm. (b) Picture of a device deformed by poking with a warm glass rod while on the skin. Scale bar, 1 cm. (c) Picture of a device collapsed under its own weight while free-standing. Scale bar, 2 cm. (d) Magnified view of a device operating in the blue region of the spectrum, without and with integrated patterns of dots that have fixed colours for calibration. Scale bar, 2 mm. (e) Picture of a device with calibration colours operating on the curved surface of the skin. Scale bar, 2 cm. (f) Picture of a device that includes a RF antenna and Joule heating element on its back surface, folded over and resting on the palm, with an enlarged view of the serpentine antenna structure (inset). Scale bar, 2 cm. (g) Schematic illustration of finite element modelling results for a device with wireless heater under tensile strain, with magnified view of the Joule heating element (inset). (h) Image of an active, wireless device collected while exposed to RF power in air, with magnified view of the colour changes induced by the heater (inset). Scale bar, 3 cm. (i) Infrared image of the same device under similar conditions, with magnified view in the region of the heater (inset). Scale bar, 3 cm.