Toward a Wirelessly Powered On-Lens Intraocular Pressure Monitoring System

Jin-Chern Chiou, Shun Hsi Hsu, Yu-Te Liao, Yu Chieh Huang, Guan Ting Yeh, Cheng Kai Kuei, Kai Shiun Dai

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


This paper presents a wireless on-lens intraocular pressure monitoring system, comprising a capacitance-to-digital converter and a wirelessly powered radio-frequency identification (RFID)-compatible communication system, for sensor control and data communication. The capacitive sensor was embedded on a soft contact lens of 200 μm thickness using commercially available biocompatible lens material, to improve compliance and reduce user discomfort. The sensor chip was shown to achieve effective number of bits greater than 10 over a capacitance range up to 50 pF while consuming only 64-μW power. The on-lens capacitive sensor could detect dielectric variation caused by changes in water content from a distance of 2 cm by using incident power from an RFID reader at 20 dBm. The maximum detectable distance was 11 cm with 30-dBm incident RF power. The rise in eye tissue temperature under 30-dBm RF exposure over an interval of 1 s was simulated and found to be less than 0.01°C.

Original languageEnglish
Article number7522639
Pages (from-to)1216-1224
Number of pages9
JournalIEEE Journal of Biomedical and Health Informatics
Issue number5
StatePublished - 1 Sep 2016


  • Capacitance-to-digital converter (CDC)
  • UHF RFID Class1 Gen2
  • capacitive sensor
  • soft contact lens

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