Fig. 4: Vital sign detection results using a cane toad as a human proxy.

a, Experimental set-up using the demonstrated system for radar sensing, which also shows its flexibility and capability for LiDAR detection. b, Experimental results for detecting the buccal-cavity movement of a cane toad using the demonstrated radar system. Camera-extracted data were used as a reference. c, Cross-correlation between the radar and camera data, showing a coefficient of 0.746. d, Frequency-domain analyses of the radar (red shadow) and camera (blue shadow) data with three top-weighted Fourier coefficients in solid and dashed lines, respectively. e, Experimental results for detecting the buccal-cavity movement of the cane toad using a LiDAR system. f, Cross-correlation between the LiDAR and camera data, showing a coefficient of 0.724. g, Frequency-domain analyses of the LiDAR (red shadow) and camera (blue shadow) data with three top-weighted Fourier coefficients in solid and dashed lines, respectively. OC, optical coupler; CIRC, optical circulator; Galvo, 2D scanning mirrors. The cross-correlation and frequency-domain analyses use time-domain data longer than the data shown in b and e.