This paper presents an implant-based wireless pressureudsensing paradigm for long-range continuous intraocularudpressure (IOP) monitoring of glaucoma patients. An implantableudparylene-based pressure sensor has been developed, featuring anudelectrical LC-tank resonant circuit for passive wireless sensingudwithout power consumption on the implanted site. The sensorudis microfabricated with the use of parylene C (poly-chlorop-udxylylene) to create a flexible coil substrate that can be foldedudfor smaller physical form factor so as to achieve minimally invasiveudimplantation, while stretched back without damage forudenhanced inductive sensor–reader coil coupling so as to achieveudstrong sensing signal. A data-processed external readout methodudhas also been developed to support pressure measurements. Byudincorporating the LC sensor and the readout method, wirelessudpressure sensing with 1-mmHg resolution in longer than 2-cm distanceudis successfully demonstrated. Other than extensive on-benchudcharacterization, device testing through six-month chronic in vivoudand acute ex vivo animal studies has verified the feasibility andudefficacy of the sensor implant in the surgical aspect, includingudrobust fixation and long-term biocompatibility in the intraocularudenvironment. With meeting specifications of practical wirelessudpressure sensing and further reader development, this sensingudmethodology is promising for continuous, convenient, direct, andudfaithful IOP monitoring.
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