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Published August 2010 | Published
Journal Article Open

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.

Additional Information

© 2010 IEEE. Manuscript received April 29, 2009; revised October 28, 2009; accepted April 21, 2010. Date of publication June 1, 2010; date of current version July 30, 2010. This work was supported in part by the Engineering Research Centers Program of the National Science Foundation (Award EEC-0310723) and in part by Bausch and Lomb. Subject Editor K. Najafi. The authors would like to thank W. Li for her assistance on data acquisition of electrical impedance measurements, D. C. Rodger for his assistance on surgical procedures and pressure sensing tests using animal models, and T. Roper for his assistance on sensor fabrication.

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