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Noninvasive measurement of the 308 nm LED ‐based UVB protection factor of sunscreens
Author(s) -
Kobylinski Susanna,
Reble Carina,
Schanzer Sabine,
Gersonde Ingo,
Wiora Georg,
Lobo Ploch Neysha,
Karrer Hans,
Kolbe Ludger,
Khazaka Georg,
Lademann Jürgen,
Meinke Martina C.
Publication year - 2021
Publication title -
journal of biophotonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 66
eISSN - 1864-0648
pISSN - 1864-063X
DOI - 10.1002/jbio.202000453
Subject(s) - sun protection factor , erythema , reflectivity , chemistry , photoaging , signal (programming language) , dermatology , medicine , optics , computer science , physics , programming language
The current method for determining the sun protection factor (SPF) requires erythema formation. Noninvasive alternatives have recently been suggested by several groups. Our group previously developed a functional sensor based on diffuse reflectance measurements with one UVB LED, which was previously evaluated on pig ear skin. Here we present the results of a systematic in vivo study using 12 sunscreens on 10 volunteers (skin types [ST] I‐III). The relationship of the UVB‐LED reflectance of unprotected skin and melanin index was determined for each ST. The spatial variation of the reflectance signal of different positions was analyzed and seems to be mainly influenced by sample inhomogeneity except for high‐protection factors (PFs) where signal levels are close to detection noise. Despite the low‐signal levels, a correlation of the measured LED‐based UVB PF with SPF reference values from test institutes with R 2 = 0.57 is obtained, suggesting a strong relationship of SPF and LED‐based UVB‐PF. Measured PFs tend to be lower for increasing skin pigmentation. The sensor design seems to be suitable for investigations where a fast measurement of relative changes of PFs, such as due to inhomogeneous application, bathing and sweating, is of interest.