title: Multi-wavelength photoplethysmography method for skin arterial pulse extraction.
abstract: In this work, we present a multi-wavelength (MW) PPG method exploiting the wavelength dependence of light penetration in skin tissue to provide depth resolution of skin blood pulsation. The MW PPG system requires two to three light sources in different wavelengths and extracts the arterial blood pulsation through a multi-wavelength multi-layer light-skin interaction model, which removes the capillary pulsation (determined from the short-wavelength PPG signal) from the long-wavelength PPG signal using absorption weighting factors that are quasi-analytically calibrated. The extracted pulsations are used to calculate blood pressure (BP) through pulse transit time (PTT), and the results are compared with those obtained from the single wavelength PPG method. The comparative study is clinically performed on 20 subjects including 10 patients diagnosed with cardiovascular diseases and 10 healthy subjects. The result demonstrates that the MW PPG method significantly improves the measurement accuracy of systolic BP (SBP), reducing the mean absolute difference between the reference and the estimated SBP values from 5.7 mmHg (for single-wavelength PPG) to 2.9 mmHg (for three-wavelength PPG).
authors.affiliation: Electronic Engineering Department, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Division of Cardiology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
authors.forename: Bryan Ping-Yen
authors.initials: BP
authors.lastname: Yan
authors.affiliation: Electronic Engineering Department, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Wen-Xuan
authors.initials: WX
authors.lastname: Dai
authors.affiliation: Electronic Engineering Department, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Xiao-Rong
authors.initials: XR
authors.lastname: Ding
authors.affiliation: Electronic Engineering Department, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; China Key Lab for Health Informatics of Chinese Academy of Sciences, Shenzhen, Guangdong, China; ytzhangapple@icloud.com.
authors.forename: Yuan-Ting
authors.initials: YT
authors.lastname: Zhang
authors.affiliation: Electronic Engineering Department, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; nzhao@ee.cuhk.edu.hk.
authors.forename: Ni
authors.initials: N
authors.lastname: Zhao
keywords: (070.6020) Continuous optical signal processing; (170.1470) Blood or tissue constituent monitoring