Chapter 11
Remote Space- and Time-Resolved Skin
Perfusion Detection Using
Photoplethysmography Imaging
Nikolai Blanik
Abstract The application of camera-based monitoring systems in medical diagnostics offers, in general, an ideal opportunity to realize contactless, robust, and unobtrusive measurement of cardiorespiratory relevant vital signs as well as spatially resolved
studies of skin perfusion dynamics. Photoplethysmography Imaging (PPGI) is one
of such promising system setups. Besides the remote data acquisition, the advantage
of PPGI over the well known PPG is that each camera sensor’s pixel can be assumed
to be an equivalent to a classical PPG sensor, working in reflective mode. Two PPGI
system generations, developed at the RWTH Aachen University, are described in
this chapter together with adequate skin illumination concepts and advanced signal
analysis of PPGI time series.
11.1 Introduction
Nowadays, photoplethysmographic sensors have become an integral part of a wide
spectrum of clinical as well as routine healthcare applications ranging from intensive
care monitoring systems like pulse oximeters, to domestic fitness tracking devices.
The simplicity and cost-effectiveness of this technique, combined with its noninvasive patient-friendly nature and accuracy and efficiency, make it a preferred
choice for the monitoring of vital body parameters. Nevertheless, such classic photoplethysmography (PPG) comes with some (minor) drawbacks: Although PPG sensors
in the reflection mode may be positioned almost anywhere on the body surface, while
in transmission mode, their use is restricted to narrow or thin body parts like fingers,
toes, or ear lobes. Whatever the location, PPG sensors require direct contact with
skin, and a cable connection to a processing unit. Furthermore, PPG signals obtained
in this manner provide information about the blood perfusion in the region directly
below the position of the sensor [1].
N. Blanik (B)
Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH
Aachen University, Aachen, Germany
e-mail: perfusion.group@hia.rwth-aachen.de
© Springer Nature Singapore Pte Ltd. 2021
V. Blazek et al. (eds.), Studies in Skin Perfusion Dynamics,
Biological and Medical Physics, Biomedical Engineering,
https://doi.org/10.1007/978-981-15-5449-0_11
177
Remote Space- and Time-Resolved Skin
Perfusion Detection Using
Photoplethysmography Imaging
Nikolai Blanik
Abstract The application of camera-based monitoring systems in medical diagnostics offers, in general, an ideal opportunity to realize contactless, robust, and unobtrusive measurement of cardiorespiratory relevant vital signs as well as spatially resolved
studies of skin perfusion dynamics. Photoplethysmography Imaging (PPGI) is one
of such promising system setups. Besides the remote data acquisition, the advantage
of PPGI over the well known PPG is that each camera sensor’s pixel can be assumed
to be an equivalent to a classical PPG sensor, working in reflective mode. Two PPGI
system generations, developed at the RWTH Aachen University, are described in
this chapter together with adequate skin illumination concepts and advanced signal
analysis of PPGI time series.
11.1 Introduction
Nowadays, photoplethysmographic sensors have become an integral part of a wide
spectrum of clinical as well as routine healthcare applications ranging from intensive
care monitoring systems like pulse oximeters, to domestic fitness tracking devices.
The simplicity and cost-effectiveness of this technique, combined with its noninvasive patient-friendly nature and accuracy and efficiency, make it a preferred
choice for the monitoring of vital body parameters. Nevertheless, such classic photoplethysmography (PPG) comes with some (minor) drawbacks: Although PPG sensors
in the reflection mode may be positioned almost anywhere on the body surface, while
in transmission mode, their use is restricted to narrow or thin body parts like fingers,
toes, or ear lobes. Whatever the location, PPG sensors require direct contact with
skin, and a cable connection to a processing unit. Furthermore, PPG signals obtained
in this manner provide information about the blood perfusion in the region directly
below the position of the sensor [1].
N. Blanik (B)
Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH
Aachen University, Aachen, Germany
e-mail: perfusion.group@hia.rwth-aachen.de
© Springer Nature Singapore Pte Ltd. 2021
V. Blazek et al. (eds.), Studies in Skin Perfusion Dynamics,
Biological and Medical Physics, Biomedical Engineering,
https://doi.org/10.1007/978-981-15-5449-0_11
177