Fig. 1: Wireless IOP monitoring system.

a The schematic diagram of a wireless contact lens system for non-invasive and continuous intraocular pressure (IOP) monitoring. At the lens end, it consists of an LCR circuit and a resistive sensor composed of PEDOT: PSS and PEDOT: PSS/PVA, which converts resistance changes into signal variations. The conventional loss LCR receiving circuit at the reader end was replaced with an equivalent negative resistance (-R) P-T symmetric system. b Utilizing this P-T effect significantly enhances detection sensitivity.