Fig. 2: Response model of eye motion.
From: Frequency-encoded eye tracking smart contact lens for human–machine interaction
a Schematic illustration of eye tracking system, including a SCL integrated with 4 frequency-encoded tags and a wide-band sweeping-frequency reader, which consisted of a near-field coil and a vector network analyzer (VNA). Inset: Equivalent circuit of eye tracking system. b \({{{{{{\rm{S}}}}}}}_{11}\) curves with fluctuating tags’ intensity caused by varying coupling coefficients \({{{{{{\rm{k}}}}}}}_{{{{{{\rm{i}}}}}}}\) under 2 different gazing points. c Response model of SCL under 2-dimension eye movement. d Details of response model under certain angles. e Common-mode eye closure signal caused by eyelid’s absorption of electromagnetic field, distinguished from the above differential mode eye-movement signal.
