430 research outputs found
DistancePPG: Robust non-contact vital signs monitoring using a camera
Vital signs such as pulse rate and breathing rate are currently measured
using contact probes. But, non-contact methods for measuring vital signs are
desirable both in hospital settings (e.g. in NICU) and for ubiquitous in-situ
health tracking (e.g. on mobile phone and computers with webcams). Recently,
camera-based non-contact vital sign monitoring have been shown to be feasible.
However, camera-based vital sign monitoring is challenging for people with
darker skin tone, under low lighting conditions, and/or during movement of an
individual in front of the camera. In this paper, we propose distancePPG, a new
camera-based vital sign estimation algorithm which addresses these challenges.
DistancePPG proposes a new method of combining skin-color change signals from
different tracked regions of the face using a weighted average, where the
weights depend on the blood perfusion and incident light intensity in the
region, to improve the signal-to-noise ratio (SNR) of camera-based estimate.
One of our key contributions is a new automatic method for determining the
weights based only on the video recording of the subject. The gains in SNR of
camera-based PPG estimated using distancePPG translate into reduction of the
error in vital sign estimation, and thus expand the scope of camera-based vital
sign monitoring to potentially challenging scenarios. Further, a dataset will
be released, comprising of synchronized video recordings of face and pulse
oximeter based ground truth recordings from the earlobe for people with
different skin tones, under different lighting conditions and for various
motion scenarios.Comment: 24 pages, 11 figure
Estimating Carotid Pulse and Breathing Rate from Near-infrared Video of the Neck
Objective: Non-contact physiological measurement is a growing research area
that allows capturing vital signs such as heart rate (HR) and breathing rate
(BR) comfortably and unobtrusively with remote devices. However, most of the
approaches work only in bright environments in which subtle
photoplethysmographic and ballistocardiographic signals can be easily analyzed
and/or require expensive and custom hardware to perform the measurements.
Approach: This work introduces a low-cost method to measure subtle motions
associated with the carotid pulse and breathing movement from the neck using
near-infrared (NIR) video imaging. A skin reflection model of the neck was
established to provide a theoretical foundation for the method. In particular,
the method relies on template matching for neck detection, Principal Component
Analysis for feature extraction, and Hidden Markov Models for data smoothing.
Main Results: We compared the estimated HR and BR measures with ones provided
by an FDA-cleared device in a 12-participant laboratory study: the estimates
achieved a mean absolute error of 0.36 beats per minute and 0.24 breaths per
minute under both bright and dark lighting.
Significance: This work advances the possibilities of non-contact
physiological measurement in real-life conditions in which environmental
illumination is limited and in which the face of the person is not readily
available or needs to be protected. Due to the increasing availability of NIR
imaging devices, the described methods are readily scalable.Comment: 21 pages, 15 figure
Camera-Based Remote Photoplethysmography for Estimation of Heart Rate using Single Board Computers
The objective of this project was to develop a wireless, noncontact monitoring system that measures multiple physiological parameters in human faces from a distance using a camera. Compared to traditional sensors, this monitoring system does not use wires or adhesives, providing a safer, more user-friendly application. The goal of the monitoring systems was to estimate heart rate (HR). The current practices of measuring HR involve collecting electrocardiogram (ECG) signals from adhesive electrodes placed on various parts of the body and using a pulse oximeter (PO) typically placed on the ear lobe or finger. We were able to successfully create 2 monitoring systems and compare their results to the PO. Both monitoring systems are low-cost at less than $200. Neither system has been shown to exist in literature thus making them novel implementations. After analysis, we found the estimated HR from one of the systems to be not significantly different from the PO readings. In conclusion, we were able to estimate HR from a distance using a camera-based system which can have many useful applications, potentially in the Neonatal ICU and in other home health settings
Photoplethysmographic imaging and analysis of pulsatile pressure wave in palmar artery at 10 wavelengths
CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.Significance
As a noncontact method, imaging photoplethysmography (iPPG) may provide a powerful tool to measure pulsatile pressure wave (PPW) in superficial arteries and extract biomarkers for monitoring of artery wall stiffness.
Aim
We intend to develop a approach for extraction of the very weak cardiac component from iPPG data by identifying locations of strong PPW signals with optimized illumination wavelength and determining pulse wave velocity (PWV).
Approach
Monochromatic in vivo iPPG datasets have been acquired from left hands to investigate various algorithms for retrieval of PPW signals, distribution maps and waveforms, and their dependence on arterial location and wavelength.
Results
A robust algorithm of pixelated independent component analysis (pICA) has been developed and combined with spatiotemporal filtering to retrieve PPW signals. Spatial distributions of PPW signals have been mapped in 10 wavelength bands from 445 to 940 nm and waveforms were analyzed at multiple locations near the palmar artery tree. At the wavelength of 850 nm selected for timing analysis, we determined PWV values from 12 healthy volunteers in a range of 0.5 to 5.8 m/s across the hand region from wrist to midpalm and fingertip.ECU Open Access Publishing Support Fun
Improvements in Remote Cardiopulmonary Measurement Using a Five Band Digital Camera
Remote measurement of the blood volume pulse via photoplethysmography (PPG) using digital cameras and ambient light has great potential for healthcare and affective computing. However, traditional RGB cameras have limited frequency resolution. We present results of PPG measurements from a novel five band camera and show that alternate frequency bands, in particular an orange band, allowed physiological measurements much more highly correlated with an FDA approved contact PPG sensor. In a study with participants (n = 10) at rest and under stress, correlations of over 0.92 (p <; 0.01) were obtained for heart rate, breathing rate, and heart rate variability measurements. In addition, the remotely measured heart rate variability spectrograms closely matched those from the contact approach. The best results were obtained using a combination of cyan, green, and orange (CGO) bands; incorporating red and blue channel observations did not improve performance. In short, RGB is not optimal for this problem: CGO is better. Incorporating alternative color channel sensors should not increase the cost of such cameras dramatically
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