Evaluation of Water Measurement Techniques for Human Skin by Dielectric Spectroscopy and Confocal Raman Spectroscopy (original) (raw)
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Journal of Biomedical Optics, 2005
Currently, measuring Raman spectra of tissues of living patients online and in real time, collecting the spectra in a very short measurement time, and allowing diagnosis immediately after the spectrum is recorded from any body region, are specific advantages that fiber optic near-infrared Raman spectroscopy (NIR RS) might represent for in vivo clinical applications in dermatology. We discuss various methodological aspects and state of the art of fiber optic NIR RS in clinical and experimental dermatology to outline its present advantages and disadvantages for measuring skin in vivo, particularly its water content. Fiber optic NIR Fourier transform (FT) RS has been introduced to dermatological diagnostics to obtain information regarding the molecular composition of the skin up to several hundred micrometers below the skin surface in a relatively fast nondestructive manner. This has been especially important for probing for in vivo assessment of cutaneous (intradermal) edema in patients patch test reactions. Fiber optic NIR FT Raman spectrometers still require further technological developments and optimization, extremely accurate water concentration determination and its intensity calculation in skin tissue, and for clinical applications, a reduction of measurement time and their size. Another promising option could be the possibility of applying mobile and compact fiber optic charge-coupled device (CCD)-based equipment in clinical dermatology.
Journal of biomedical photonics & engineering, 2017
Diffuse reflectance spectroscopy system was developed for estimation of skin hydration in the near-infrared spectral range of 900-1700 nm. Experimental setup consisted of a near-infrared spectrometer, Y-type fiber optics probe with 1 detection and 6 illumination fibers, halogen-tungsten light source and a PC. By analyzing diffuse reflectance spectrum, a parameter representing skin hydration by performing baseline correction and calculating the area under the 1450 nm water absorption maximum is proposed. A clinical study was performed acquiring data of skin hydration of 39 patients' forearm skin. Results of the developed system are compared to results obtained by a commercial device based on skin conductance measurements.
Applications of Raman spectroscopy to skin research
Skin Research and Technology, 1997
Backgroundlaims: Raman spectroscopy has been used for a range of biomedical applications: the study of normal and diseased tissues, and the interaction of chemical agents with tissues, implants and even single cells. The object here was to review the extent to which the Raman spectroscopic technique has been applied to skin research, considering the implications of different instrumentation, comparing animal and human skin, healthy and diseased skin and in vivo and in vitro sampling.
Combined In Vivo Confocal Raman Spectroscopy and Confocal Microscopy of Human Skin
Biophysical Journal, 2003
In vivo confocal Raman spectroscopy is a noninvasive optical method to obtain detailed information about the molecular composition of the skin with high spatial resolution. In vivo confocal scanning laser microscopy is an imaging modality that provides optical sections of the skin without physically dissecting the tissue. A combination of both techniques in a single instrument is described. This combination allows the skin morphology to be visualized and (subsurface) structures in the skin to be targeted for Raman measurements. Novel results are presented that show detailed in vivo concentration profiles of water and of natural moisturizing factor for the stratum corneum that are directly related to the skin architecture by in vivo crosssectional images of the skin. Targeting of skin structures is demonstrated by recording in vivo Raman spectra of sweat ducts and sebaceous glands in situ. In vivo measurements on dermal capillaries yielded high-quality Raman spectra of blood in a completely noninvasive manner. From the results of this exploratory study we conclude that the technique presented has great potential for fundamental skin research, pharmacology (percutaneous transport), clinical dermatology, and cosmetic research, as well as for noninvasive analysis of blood analytes, including glucose.
In vitro and in vivo Raman spectroscopy of human skin
Biospectroscopy, 1998
Noninvasive techniques that provide detailed information about molecular composition, structure, and interactions are crucial to further our understanding of the relation between skin disease and biochemical changes in the skin, as well as for the development of penetration enhancers for transdermal drug administration. In this study we present in vitro and in vivo Raman spectra of human skin. Using a Raman microspectrometer, in vitro spectra were obtained of thin cross sections of human skin. They provided insight into the molecular composition of different skin layers. Evidence was found for the existence of a large variation in lipid content of the stratum corneum. A simple experimental setup for in vivo confocal Raman microspectroscopy of the skin was developed. In vivo Raman spectra of the stratum corneum were obtained at different positions of the arm and hand of three volunteers. They provided evidence for differences in the concentration of natural moisturizing factor at the...
Translational Biophotonics, 2019
This article describes a unique noninvasive capability to determine the concentration (in mg/cm 3) and total amount of topically applied materials in the skin (in μg/cm 2 of skin surface). It is based on in vivo confocal Raman spectroscopy. A theoretical derivation is given of a general method to calculate a concentration ratio from a Raman spectrum of a material in a medium, which can be a solvent or other matrix, such as the skin. A practical implementation of the method is then presented along with a clarification of the assumptions used and applied to a quantitative analysis of the in vivo skin penetration of trans-retinol and propylene glycol (PG). A comparison was made between the concentrations profiles of retinol and PG found in the skin and the concentrations of retinol and PG that had been applied to the skin. Determination of the amount of these materials in the skin at different timepoints after topical application also enabled a straightforward calculation of the flux of materials into the skin (in μg cm −2 h).
Sensors
Dermal water content is an important biophysical parameter in preserving skin integrity and preventing skin damage. Traditional electrical-based and open-chamber evaporimeters have several well-known limitations. In particular, such devices are costly, sizeable, and only provide arbitrary outputs. They also do not permit continuous and non-invasive monitoring of dermal water content, which can be beneficial for various consumer, clinical, and cosmetic purposes. We report here on the design and development of a digital multi-wavelength optical sensor that performs continuous and non-invasive measurement of dermal water content. In silico investigation on porcine skin was carried out using the Monte Carlo modeling strategy to evaluate the feasibility and characterize the sensor. Subsequently, an in vitro experiment was carried out to evaluate the performance of the sensor and benchmark its accuracy against a high-end, broad band spectrophotometer. Reference measurements were made agai...
Novel confocal Raman microscopy method to investigate hydration mechanisms in human skin
Skin Research and Technology, 2019
Background: Skin hydration is essential for maintaining stratum corneum (SC) flexibility and facilitating maturation events. Moisturizers contain multiple ingredients to maintain and improve skin hydration although a complete understanding of hydration mechanisms is lacking. The ability to differentiate the source of the hydration (water from the environment or deeper skin regions) upon application of product will aid in designing more efficacious formulations. Materials and Methods: Novel confocal Raman microscopy (CRM) experiments allow us to investigate mechanisms and levels of hydration in the SC. Using deuterium oxide (D 2 O) as a probe permits the differentiation of endogenous water (H 2 O) from exogenous D 2 O. Following topical application of D 2 O, we first compare in vivo skin depth profiles with those obtained using ex vivo skin. Additional ex vivo experiments are conducted to quantify the kinetics of D 2 O diffusion in the epidermis by introducing D 2 O under the dermis. Results: Relative D 2 O depth profiles from in vivo and ex vivo measurements compare well considering procedural and instrumental differences. Additional in vivo experiments where D 2 O was applied following topical glycerin application increased the longevity of D 2 O in the SC. Reproducible rates of D 2 O diffusion as a function of depth have been established for experiments where D 2 O is introduced under ex vivo skin. Conclusion: Unique information regarding hydration mechanisms are obtained from CRM experiments using D 2 O as a probe. The source and relative rates of hydration can be delineated using ex vivo skin with D 2 O underneath. One can envision comparing these depth-dependent rates in the presence and absence of topically applied hydrating agents to obtain mechanistic information.
Assessment of Skin Deep Layer Biochemical Profile Using Spatially Offset Raman Spectroscopy
Applied Sciences, 2021
Skin cancer is currently the most common type of cancer with millions of cases diagnosed worldwide yearly. The current gold standard for clinical diagnosis of skin cancer is an invasive and relatively time-consuming procedure, consisting of visual examination followed by biopsy collection and histopathological analysis. Raman spectroscopy has been shown to efficiently aid the non-invasive diagnosis of skin cancer when probing the surface of the skin. In this study, we employ a recent development of Raman spectroscopy (Spatially Offset Raman Spectroscopy, SORS) which is able to look deeper in tissue and create a deep layer biochemical profile of the skin in areas where cancer lesions subtly evolve. After optimizing the measurement parameters on skin tissue phantoms, we then adopted SORS on human skin tissue from different anatomical areas to investigate the contribution of the different skin layers to the recorded Raman signal. Our results show that using a diffuse beam with zero off...