Non-Invasive Intraocular Pressure Monitoring System Based on Amplitude and Phase Detection Technology

This study proposes a non-invasive intraocular pressure monitoring system based on piezoresistive thin-film pressure sensor with amplitude and phase detection technology. The system utilizes the piezoresistive effect of the two-wire piezoresistive sensor to modulate the resistance change caused by intraocular pressure (IOP) into a two-parameter change of RF signal amplitude and phase through electromagnetic induction coupling, and the IOP value is solved by MCU based on the leastsquares fitting after the receiving end has been processed by frequency mixing, filtering, and wave detection. The experiments show that the system fits the real pressure and the converted pressure within the range of $0-30 \mathrm{mmHg}$ with a goodness-of-fit of 0.896, a maximum absolute error of 1.94 mmHg, and an RMSE of 0.49 mmHg, which verifies the feasibility of this non-invasive IOP monitoring scheme.