a, Infrared image of a 4× 4 TCR sensor array mounted on the palm during stimulus experiments. b,c, Temperature of the palm measured with an infrared camera (blue) and a sensor array (red, offset for clarity) during mental (b) and physical stimulus tests (c). d, Normalized Fourier transform of temperature measured on the forearm using a TCR sensor array (red), and using infrared camera evaluation through a transparent region of the array (blue). Both measurements show prominent peaks around 0.01 and 0.04 Hz.