A minimally invasive implantable wireless pressure sensor for continuous IOP monitoring

Girish Chitnis, Teimour Maleki, Brian Samuels, Louis B. Cantor, Babak Ziaie

Research output: Contribution to journalArticle

75 Scopus citations


This paper presents a minimally invasive implantable pressure sensing transponder for continuous wireless monitoring of intraocular pressure (IOP). The transponder is designed to make the implantation surgery simple while still measuring the true IOP through direct hydraulic contact with the intraocular space. Furthermore, when IOP monitoring is complete, the design allows physicians to easily retrieve the transponder. The device consists of three main components: 1) a hypodermic needle (30 gauge) that penetrates the sclera through pars plana and establishes direct access to the vitreous space of the eye; 2) a micromachined capacitive pressure sensor connected to the needle back-end; and 3) a flexible polyimide coil connected to the capacitor forming a parallel LC circuit whose resonant frequency is a function of IOP. Most parts of the sensor sit externally on the sclera and only the needle penetrates inside the vitreous space. In vitro tests show a sensitivity of 15 kHz/mmHg with approximately 1-mmHg resolution. One month in vivo implants in rabbits confirm biocompatibility and functionality of the device.

Original languageEnglish (US)
Article number6220856
Pages (from-to)250-256
Number of pages7
JournalIEEE Transactions on Biomedical Engineering
Issue number1
StatePublished - Jan 7 2013


  • Glaucoma
  • implantable microdevice
  • intraocular pressure (IOP)
  • wireless sensing

ASJC Scopus subject areas

  • Biomedical Engineering

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