Browsing by Author "Kuei, Cheng-Kai"

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A Wirelessly Powered Smart Contact Lens with Reconfigurable Wide Range and Tunable Sensitivity Sensor Readout Circuitry
(2017-01-01)
Chiou, Jin-Chern
;
Hsu, Shun-Hsi
;
Huang, Yu-Chieh
;
Yeh, Guan-Ting
;
Liou, Wei-Ting
This study presented a wireless smart contact lens system that was composed of a reconfigurable capacitive sensor interface circuitry and wirelessly powered radio-frequency identification (RFID) addressable system for sensor control and data communication. In order to improve compliance and reduce user discomfort, a capacitive sensor was embedded on a soft contact lens of 200 mu m thickness using commercially available bio-compatible lens material and a standard manufacturing process. The results indicated that the reconfigurable sensor interface achieved sensitivity and baseline tuning up to 120 pF while consuming only 110 mu W power. The range and sensitivity tuning of the readout circuitry ensured a reliable operation with respect to sensor fabrication variations and independent calibration of the sensor baseline for individuals. The on-chip voltage scaling allowed the further extension of the detection range and prevented the implementation of large on-chip elements. The on-lens system enabled the detection of capacitive variation caused by pressure changes in the range of 2.25 to 30 mmHg and hydration level variation from a distance of 1 cm using incident power from an RFID reader at 26.5 dBm.
An Addressable UHF EPCGlobal Class1 Gen2 Sensor IC for Wireless IOP Monitoring on Contact Lens
(2015)
Chiou, Jin-Chern
;
Hsu, Shun-Hsi
;
Kuei, Cheng-Kai
;
Wu, Tsung-Wei
;
電子工程學系及電子研究所
In this paper, an addressable UHF EPCGlobal Class1 Gen2 sensor IC for wireless intraocular pressure (IOP) monitoring on contact lens sensor device is proposed. The proposed sensor IC consists of RFID Analog/RF Front End, capacitive sensor readout circuit, and digital processing unit. RFID Analog/RF Front End is used for power management and data transmission. Sensor Readout Circuit will convert the measured capacitor value to digital format for digital processing unit. Digital processing unit is used as processor not only for sensor value processing obtained from the sensor readout circuit, but also for bidirectional communication between RFID reader and sensor IC. This sensor IC architecture combined with specific sensor and corresponding sensor readout circuit can be widely used as noninvasive biomedical sensor devices and systems. Wireless communication and sensor data transmission are implemented with UHF RFID technology, providing much flexibility and can reduce self-developed firmware effort for this architecture in the future.
An RFID-based On-lens Sensor System for Long-Term IOP Monitoring
(2015)
Hsu, Shun-Hsi
;
Chiou, Jin-Chern
;
Liao, Yu-Te
;
Yang, Tzu-Sen
;
Kuei, Cheng-Kai
In this paper, an RFID-based on-lens sensor system is proposed for noninvasive long-term intraocular pressure monitoring. The proposed sensor IC, fabricated in a 0.18um CMOS process, consists of capacitive sensor readout circuitry, RFID communication circuits, and digital processing units. The sensor IC is integrated with electroplating capacitive sensors and a receiving antenna on the contact lens. The sensor IC can be wirelessly powered, communicate with RFID compatible equipment, and perform IOP measurement using on-lens capacitive sensor continuously from a 2cm distance while the incident power from an RFID reader is 20 dBm. The proposed system is compatible to Gen2 RFID protocol, extending the flexibility and reducing the self-developed firmware efforts.
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.