Chapter 13
Concluding Remarks and New Horizons
in Skin Perfusion Studies
Steffen Leonhardt
Abstract This chapter presents some conclusions on the preceding chapters. It
summarizes the historical development of camera-based photoplethysmography
(PPG). PPG Imaging (PPGI) has seen a dramatic increase in publications on the
subject, and in parallel to this increasing amount of scientific activity, a dramatic
technological development makes cameras much smaller, cheaper, and more robust.
This, of course, is a prerequisite for using cameras as a sensor in customized unobtrusive applications. This chapter also points at some future technical directions, particularly at hybrid imaging in which RGB/NIR cameras may be combined with other
frequency bands. As an example, long-wave infrared thermography (LWIR/IRT) is
a camera technology that has also seen a dramatic drop in prices and size in recent
years, yet from a higher starting point. As the first hybrid camera systems combining
these two modalities have recently become available, there is hope for entirely new
applications. Finally, PPGI allows looking at more than just heart rate and oxygen
saturation. The authors suggest looking at, e.g., low-frequency rhythms for which
there is some evidence for completely new applications.
13.1 Introduction
This book has presented the history and the fundamentals of the functional assessment of dermal physiological and/or pathophysiological blood perfusion rhythmicity,
collected by photoplethysmography (PPG) and photoplethysmography imaging
(PPGI) over the last few decades, especially over the last 20 years. As Fig. 13.1
indicates, the interest in these bio-optical techniques has been continuously growing,
which is certainly due to the upcoming new applications in remote health care and
ambient assisted living scenarios, but also a result of technological advances in
miniaturization and cost-effectiveness.
S. Leonhardt (B)
Chair for Medical Information Technology, Helmholtz Institute for Biomedical Engineering,
RWTH Aachen University, Aachen, Germany
e-mail: leonhardt@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_13
223
Concluding Remarks and New Horizons
in Skin Perfusion Studies
Steffen Leonhardt
Abstract This chapter presents some conclusions on the preceding chapters. It
summarizes the historical development of camera-based photoplethysmography
(PPG). PPG Imaging (PPGI) has seen a dramatic increase in publications on the
subject, and in parallel to this increasing amount of scientific activity, a dramatic
technological development makes cameras much smaller, cheaper, and more robust.
This, of course, is a prerequisite for using cameras as a sensor in customized unobtrusive applications. This chapter also points at some future technical directions, particularly at hybrid imaging in which RGB/NIR cameras may be combined with other
frequency bands. As an example, long-wave infrared thermography (LWIR/IRT) is
a camera technology that has also seen a dramatic drop in prices and size in recent
years, yet from a higher starting point. As the first hybrid camera systems combining
these two modalities have recently become available, there is hope for entirely new
applications. Finally, PPGI allows looking at more than just heart rate and oxygen
saturation. The authors suggest looking at, e.g., low-frequency rhythms for which
there is some evidence for completely new applications.
13.1 Introduction
This book has presented the history and the fundamentals of the functional assessment of dermal physiological and/or pathophysiological blood perfusion rhythmicity,
collected by photoplethysmography (PPG) and photoplethysmography imaging
(PPGI) over the last few decades, especially over the last 20 years. As Fig. 13.1
indicates, the interest in these bio-optical techniques has been continuously growing,
which is certainly due to the upcoming new applications in remote health care and
ambient assisted living scenarios, but also a result of technological advances in
miniaturization and cost-effectiveness.
S. Leonhardt (B)
Chair for Medical Information Technology, Helmholtz Institute for Biomedical Engineering,
RWTH Aachen University, Aachen, Germany
e-mail: leonhardt@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_13
223