Browsing by Author "Dai, Kai-Shiun"

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Toward a Wirelessly Powered On-Lens Intraocular Pressure Monitoring System
(2016-09)
Chiou, Jin-Chern
;
Hsu, Shun-Hsi
;
Liao, Yu-Te
;
Huang, Yu-Chieh
;
Yeh, Guan-Ting
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 mu m 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-mu W 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 degrees C.
Toward a Wirelessly Powered On-Lens Intraocular Pressure Monitoring System
(2016-09-01)
Chiou, Jin-Chern
;
Hsu, Shun-Hsi
;
Liao, Yu-Te
;
Huang, Yu-Chieh
;
Yeh, Guan-Ting
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 mu m 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-mu W 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 degrees C.