A 0.5- \mu V 12- \mu W Wirelessly Powered Patch-Type Healthcare Sensor for Wearable Body Sensor Network

• Published in: IEEE journal of solid-state circuits Vol. 45; no. 11; pp. 2356 - 2365
• Main Authors: Long Yan, Yoo, Jerald, Binhee Kim, Hoi-Jun Yoo
• Format: Journal Article
• Language: English
• Published: IEEE 01.11.2010
• Subjects: Battery-less sensor; continuous health monitoring; dry electrode; electrocardiogram (ECG); Electrodes; Fabrics; Impedance; Medical services; nested chopping; Noise; planar-fashionable circuit board (P-FCB); Powders; Skin; stainless steel powder; wearable body sensor network (W-BSN); wearable healthcare
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2010.2065831

A wirelessly powered patch-type healthcare sensor IC is presented for a wearable body sensor network (W-BSN) to continuously monitor personal vital signals. Thick-film electrodes are screen printed on a fabric by planar-fashionable circuit board (P-FCB) technology on which stainless steel powder with a grain size of 100 μ m is added to reduce both contact impedance as well as motion artifacts. A nested chopped amplifier (NCA) is designed and optimized for the proposed patch-type healthcare sensor with a reduced electrode referred noise of 0.5 μV rms . A programmable gain and bandwidth amplifier (PGA) stage is also implemented to accommodate various dynamic ranges of vital signals. A 10-b folded successive approximation register (SAR) analog-to-digital converter (ADC) reduces capacitive digital-to-analog conversion size by 94% and relaxes the power budget of the ADC driver by 36%. Measured sensor resolution is 9.2 b and rejects common-mode interference larger than 100 dB while consuming only 12 μ W of power supplied wirelessly. A 2.0 mm × 1.3 mm sensor IC is fabricated in 0.18-μm 1P6M CMOS technology. The chip is directly integrated between two screen printed electrodes and stacked by a screen printed fabric inductor. With the proposed patch-type sensor, personal healthcare without expensive batteries is possible in W-BSN and greatly improves wearability and convenience in use.