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A wireless, low-drift, implantable intraocular pressure sensor with parylene-on-oil encapsulation

Agarwal, Abhinav and Shapero, Aubrey and Rodger, Damien and Humayun, Mark and Tai, Yu-Chong and Emami, Azita (2018) A wireless, low-drift, implantable intraocular pressure sensor with parylene-on-oil encapsulation. In: 2018 IEEE Custom Integrated Circuits Conference (CICC). IEEE , Piscataway, NJ, pp. 1-4. ISBN 978-1-5386-2483-8.

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This paper presents a wireless, implantable continuous intraocular pressure (IOP) monitoring system that features a parylene-on-oil sensor encapsulation method for achieving long-term low-drift in vivo. The system is implanted in the superotemporal quadrant of the eye between the sclera and conjunctiva. It consists of a commercial pressure sensor (STMicroelectronics LPS25H) with digital readout, a 65nm CMOS chip that supports wireless power/data telemetry and the I2C serial communication interface with the pressure sensor. The chip and pressure sensor are assembled on a flexible polyimide PCB, and then the sensor is submerged in biocompatible silicone oil and coated with parylene in situ. The implant uses an on-chip integrated RF coil to receive power from near-field RF coupling at 915 MHz and transmit measurement bits via RF-backscattering to an external reader. A 2 mm × 1.2 mm chip is fabricated in TSMC 65nm CMOS process. The IOP implant achieves a pressure sensitivity of 0.17 mm Hg with a total power consumption of 9.7μW. We demonstrate pressure offset drift of less than 0.5 mmHg for more than 4 months over a temperature range of 27–38 °C. The implant successfully tracks induced IOP variations in a porcine eye ex vivo, validating the system functionality and surgical implantation.

Item Type:Book Section
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URLURL TypeDescription
Rodger, Damien0000-0002-1583-5946
Humayun, Mark0000-0002-5830-5208
Tai, Yu-Chong0000-0001-8529-106X
Emami, Azita0000-0003-2608-9691
Additional Information:© 2018 IEEE. The authors thank Samson Chen (Caltech Nanofabrication Lab) for help with the wireless reader, Trevor Roper (Caltech MEMS Lab) for maintaining equipment, Cameron Sylber for help with longevity tests, and MOSIS for chip fabrication. This work was supported by the Rosen Bioengineering Center Pilot Grant, the Heritage Medical Research Institute, the L. K. Whittier Foundation, and an unrestricted departmental grant from Research to Prevent Blindness.
Group:Heritage Medical Research Institute
Funding AgencyGrant Number
Donna and Benjamin M. Rosen Bioengineering CenterUNSPECIFIED
Heritage Medical Research InstituteUNSPECIFIED
L. K. Whittier FoundationUNSPECIFIED
Research to Prevent BlindnessUNSPECIFIED
Subject Keywords:Intraocular Pressure Sensor (IOP); Implantable; Parylene-on-oil; Pressure Sensor Packaging; Low-Drift; Wireless Powering; RF Backscattering
Record Number:CaltechAUTHORS:20180518-135417850
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Official Citation:A. Agarwal, A. Shapero, D. Rodger, M. Humayun, Y. C. Tai and A. Emami, "A wireless, low-drift, implantable intraocular pressure sensor with parylene-on-oil encapsulation," 2018 IEEE Custom Integrated Circuits Conference (CICC), San Diego, CA, USA, 2018, pp. 1-4. doi: 10.1109/CICC.2018.8357049
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86459
Deposited By: George Porter
Deposited On:18 May 2018 21:23
Last Modified:15 Nov 2021 20:38

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