Abstract:We report a method on quantitative and simultaneous noncontact in-vivo hydration and sebum measurements of the skin using an infrared optical spectroscopic set-up. The method utilizes differential detection with three wavelengths 1720, 1750, and 1770 nm, corresponding to the lipid vibrational bands that lay "in between" the prominent water absorption bands. We have used an emulsifier containing hydro-and lipophilic components to mix water and sebum in various volume fractions which was applied to the skin to mimic different oily-dry skin conditions. We also measured the skin sebum and hydration values on the forehead under natural conditions and its variations to external stimuli. Good agreement was found between our experimental results and reference values measured using conventional biophysical methods such as Corneometer and Sebumeter. H. Behrendt, and J. Ring, "Skin Surface pH, Stratum corneum Hydration, Trans-epidermal water loss and skin roughness related to atopic eczema and skin dryness in a population of primary school children," Acta Derm. Venereol. 80(3), 188-191 (2000). 11. M. Janssens, J. van Smeden, G. J. Puppels, A. P. M. Lavrijsen, P. J. Caspers, and J. A. Bouwstra, "Lipid to protein ratio plays an important role in the skin barrier function in patients with atopic eczema," Br. J. Dermatol. 170(6), 1248-1255 (2014). 12. J. Kim, J. Jeon, and H. Song, "Evaluation of the degree of skin dryness and the effect of moisturizing therapy in scalp psoriasis", Annual Global Pharma Summit, Philadelphia, USA (2015). #261736Received 23 Dermatol. 96(6), 845-851 (1990 (InTech, Rijeka, 2012). 21. Y. Shirai, "Skin condition observation apparatus," U.S. Patent 10,642,683, Aug. 19, 2003. 22. H. Iwasaki, K. Miyazawa, and S. Nakauchi, "Visualization of the human face skin moisturizing-ability by spectroscopic imaging using two near-infrared bands," Proc. SPIE 6062, 606203 (2006). 23. D. P. Lookingbill and W. J. Cunliffe, "A direct gravimetric technique for measuring sebum excretion rate," Br.

Abstract:We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype. The performance and linearity of the method was compared with different professional gloss measurement devices based on the ratio of specular to diffuse intensity. We demonstrate the feasibility for in-vivo skin gloss measurements by quantifying the temporal evolution of skin gloss after application of standard paraffin cream bases on skin. The presented method opens new possibilities in the fields of cosmetology and dermatopharmacology for measuring the skin gloss and resorption kinetics and the pharmacodynamics of various external agents.

Abstract:We demonstrate the feasibility of short wave infrared (SWIR) spectroscopy combined with tape stripping for depth profiling of lipids and water in the stratum corneum of human skin. The proposed spectroscopic technique relies on differential detection at three wavelengths of 1720, 1750, and 1770 nm, with varying ratio of the lipid-to-water absorption coefficient and an 'isosbestic point'. Comparison of the data acquired using SWIR spectroscopy with that obtained by a gold standard for non-invasive quantitative molecularspecific skin measurements, namely confocal Raman spectroscopy (CRS), revealed specificity of the proposed modality for water and lipid quantification. At the same time, we provide evidence showing aberrant sensitivity of Corneometer hydration read-outs to the presence of skin surface lipids, and a lack of sensitivity of the Sebumeter when attempting to measure the lipids of the cornified lipid envelope and intracellular lipid layers. We conclude that a spectroscopic SWIR-based spectroscopic method combined with tape stripping has the potential for depth profiling of the stratum corneum water and lipids, due to superior measurement sensitivity and specificity compared to the Corneometer and Sebumeter. References and links1. D. J. Tobin, "Introduction to skin aging," J. Tissue Viability 26(1), 37-46 (2017). 2. P. C. Arck, A. Slominski, T. C. Theoharides, E. M. Peters, and R. Paus, "Neuroimmunology of stress: skin takes center stage," J. Invest. Dermatol. 126(8), 1697-1704 (2006). 3. K. R. Feingold and P. M. Elias, "Role of lipids in the formation and maintenance of the cutaneous permeability barrier," Biochim. Biophys. Acta 1841(3), 280-294 (2014). 4. D. J. Tobin, "Biochemistry of human skin--our brain on the outside," Chem. Soc. Rev. 35(1), 52-67 (2006). 5. M. Akiyama, "Corneocyte lipid envelope (CLE), the key structure for skin barrier function and ichthyosis pathogenesis," J. Dermatol. Sci. 88(1), 3-9 (2017). 6. K. C. Madison, "Barrier function of the skin: "la raison d'être" of the epidermis," J. Invest. Dermatol. 121(2), 231-241 (2003). 7. D. J. Tobin, "Introduction to skin aging," J. Tissue Viability 26(1), 37-46 (2017 75-83 (2015). 13. R. J. Richters, N. E. Uzunbajakava, D. Falcone, J. C. Hendriks, E. J. Jaspers, P. C. van de Kerkhof, and P. E. van Erp, "Clinical, biophysical and immunohistochemical analysis of skin reactions to acute skin barrier disruptiona comparative trial between participants with sensitive skin and those with nonsensitive skin," Br. J. Dermatol. 174(5), 1126-1133 (2016). 14. M. Akiyama, "Corneocyte lipid envelope (CLE), the key structure for skin barrier function and ichthyosis pathogenesis," J. Dermatol. Sci. 88(1), 3-9 (2017). 15. M. Sullivan, N.B. Silverberg, "Current and emerging concepts in atopic dermatitis pathogenesis," Clin, Dermatol.35 (

Skin health characterized by a system of water and lipids in Stratum Corneum provide protection from harmful external elements and prevent trans-epidermal water loss. Skin hydration (moisture) and sebum (skin surface lipids) are considered to be important factors in skin health; a right balance between these components is an indication of skin health and plays a central role in protecting and preserving skin integrity. In this manuscript we present an infrared spectroscopic method for simultaneous and quantitative measurement of skin hydration and sebum levels utilizing differential detection with three wavelengths 1720, 1750, and 1770 nm, corresponding to the lipid vibrational bands that lie "in between" the prominent water absorption bands. The skin sebum and hydration values on the forehead under natural conditions and its variations to external stimuli were measured using our experimental set-up. The experimental results obtained with the optical set-up show good correlation with the results obtained with the commercially available instruments Corneometer and Sebumeter.