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Wireless Intraocular Pressure Sensing Using Microfabricated Minimally Invasive Flexible-Coiled LC Sensor Implant
This paper presents an implant-based wireless pressure
sensing paradigm for long-range continuous intraocular
pressure (IOP) monitoring of glaucoma patients. An implantable
parylene-based pressure sensor has been developed, featuring an
electrical LC-tank resonant circuit for passive wireless sensing
without power consumption on the implanted site. The sensor
is microfabricated with the use of parylene C (poly-chlorop-
xylylene) to create a flexible coil substrate that can be folded
for smaller physical form factor so as to achieve minimally invasive
implantation, while stretched back without damage for
enhanced inductive sensor–reader coil coupling so as to achieve
strong sensing signal. A data-processed external readout method
has also been developed to support pressure measurements. By
incorporating the LC sensor and the readout method, wireless
pressure sensing with 1-mmHg resolution in longer than 2-cm distance
is successfully demonstrated. Other than extensive on-bench
characterization, device testing through six-month chronic in vivo
and acute ex vivo animal studies has verified the feasibility and
efficacy of the sensor implant in the surgical aspect, including
robust fixation and long-term biocompatibility in the intraocular
environment. With meeting specifications of practical wireless
pressure sensing and further reader development, this sensing
methodology is promising for continuous, convenient, direct, and
faithful IOP monitoring
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