The optics of skin: why skin looks pink instead of orange

Time: Friday, October 27, 2017 - 4:00pm - 5:00pm
Type: Seminar Series
Presenter: Steven L. Jacques; Professor, Biomedical Engineering, Tufts University
Room/Office: Room 000
51 Prospect Street
New Haven, CT 06511
United States

Department of Computer Science Fall 2017 Colloquium Series

"The Optics of Skin: Why Skin Looks Pink Instead of Orange"

Steven L. Jacques
Professor, Biomedical Engineering, Tufts University 

Abstract: The skin is an optically turbid medium with embedded absorbers (blood, melanin, water) and scatterers (collagen, lipid membranes). The scattering greatly a ects the observed color of the skin. A homogeneous mixture of scatterers and blood will yield an orange color, since absorption by blood scales as blue > green > red. But the architecture of the skin has a super cial layer of relatively low blood content: the epidermis and super cial papillary dermis. Hence, blue light can re ect from this super cial layer before seeing any blood while green and red light penetrate more deeply and see the deeper blood. This moves the skin color from orange to pink. Of course, melanin o ers an additional absorption lter that strongly attenuates blue light, but subsurface melanin yields the blue coloring of Nevus of Ota. In summary, skin architecture plays
a key role in the appearance of skin color.

Bio: Steven L. Jacques, Ph.D., received a B.S. degree in Biology at M.I.T., and an M.S. degree in Electrical Engineering and Computer Science and a Ph.D. degree in Biophysics and Medical Physics from the University of California-Berkeley (1984), where he used dielectric microwave measurements to explore the in vivo distribution of water in the stratum corneum of human skin. In 1983, he joined the Wellman Laboratory for Photomedicine at Massachusetts General Hospital, rising to a Lecturer in Dermatology / Bioengineering, Harvard Medical School. His team developed the use of Monte Carlo computer simulations to study optical transport in biological tissues, which is now widely used in the eld of biophotonics. In 1988, he joined the University of Texas M. D. Anderson Cancer as an Assistant Professor of Urology/Biophysics and established a laboratory developing novel laser and optical methods for medicine, later achieving a tenured position as Associate Professor. He developed a hand-held spectrometer and the analysis software to noninvasively measure hyperbilirubinemia in newborns. This device was patented, licensed, and FDA approved to replace heel stick tests, and is now in practice in neonatal care. As of 2009, over 20 million newborns have been tested with the device. In 1996, he moved to Oregon as Professor of Biomedical Engineering & Dermatology at Oregon Health & Science University. In September 2017, he joined Tufts University in Biomedical Engineering.

Host: Alex Doronin

Co-sponsored by the Departments of Computer Science and Biomedical Engineering