Fig. 3: Experimental validation.
From: Metasurface-enabled multifunctional single-frequency sensors without external power
a Measurement sample and measurement system using light and heat sources in free space. b Frequency-domain reflectance. The temperature, light intensity and input power were set to 22.1 °C, 328 lux and 30 dBm, respectively. c–e Time-domain reflectance of the metasurface-based sensor using (c) temperature-dependent capacitors and fixed resistors (10 kΩ), (d) fixed capacitors (1 nF) and photocells and (e) temperature-dependent capacitors and photocells. The frequency was set to optimal values to increase the time-domain variation in (c–e) (specifically, 3.82 GHz in (c) and (d) and 3.76 GHz in (e)).
