Investigating skin barrier function utilizing reflectance NIR Spectroscopy

Near Infrared Spectroscopy is seen as a potentially valuable technique for skin analysis, and has been employed by many previous studies to measure skin hydration, since it is competent of providing information regarding various functional groups including OH, CH and NH bands. The aim of this study was to investigate the capability of further utilizing this method by attempting to analyze skin barrier function as well as water content, through the evaluation of skin water uptake on two test sites, one untreated, and another treated with a high lipid moisturizer for a period of 7 days. Reflectance NIRS measurements were supported by capacitance readings obtained using the Corneometer® CM 825. Baseline recordings taken on the first day following treatment showed that more differences were observed between the treated and untreated sites in the regions belonging to, or are influenced by CH and NH groups rather than purely on the water bands. On the hand, moisture levels measured after placing a wet patch on the skin remained nearly equal for both sites but second derivative spectra showed that a clear contrast existed between absorbance heights at the water bands of the treated and untreated, suggesting that moisturizer use could have limited water uptake to a more superficial layer of the skin, whereas for the untreated site, the opposite would have been true and water was able to penetrate deeper. Overall, results here suggest that NIR spectroscopy can possibly provide valuable information not only on skin water contents but perhaps on other skin parameters such as barrier function

Review of Modern Techniques for the Assessment of Skin Hydration

Skin hydration is a complex process that influences the physical and mechanical properties of skin. Various technologies have emerged over the years to assess this parameter, with the current standard being electrical probe-based instruments. Nevertheless, their inability to provide detailed information has prompted the use of sophisticated spectroscopic and imaging methodologies, which are capable of in-depth skin analysis that includes structural and composition details. Modern imaging and spectroscopic techniques have transformed skin research in the dermatological and cosmetics disciplines, and are now commonly employed in conjunction with traditional methods for comprehensive assessment of both healthy and pathological skin. This article reviews current techniques employed in measuring skin hydration, and gives an account on their principle of operation and applications in skin-related research

A Newcomer\u27s Guide to Functional Near Infrared Spectroscopy Experiments

This review presents a practical primer for functional near-infrared spectroscopy (fNIRS) with respect to technology, experimentation, and analysis software. Its purpose is to jump-start interested practitioners considering utilizing a non-invasive, versatile, nevertheless challenging window into the brain using optical methods. We briefly recapitulate relevant anatomical and optical foundations and give a short historical overview. We describe competing types of illumination (trans-illumination, reflectance, and differential reflectance) and data collection methods (continuous wave, time domain and frequency domain). Basic components (light sources, detection, and recording components) of fNIRS systems are presented. Advantages and limitations of fNIRS techniques are offered, followed by a list of very practical recommendations for its use. A variety of experimental and clinical studies with fNIRS are sampled, shedding light on many brain-related ailments. Finally, we describe and discuss a number of freely available analysis and presentation packages suited for data analysis. In conclusion, we recommend fNIRS due to its ever-growing body of clinical applications, state-of-the-art neuroimaging technique and manageable hardware requirements. It can be safely concluded that fNIRS adds a new arrow to the quiver of neuro-medical examinations due to both its great versatility and limited costs

Design and Analysis of a Continuous and Non-Invasive Multi-Wavelength Optical Sensor for Measurement of Dermal Water Content

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 against gravimetric analysis. The results demonstrate that the developed sensor can deliver accurate, continuous, and non-invasive measurement of skin hydration through measurement of dermal water content. Remarkably, the novel design of the sensor exceeded the performance of the high-end spectrophotometer due to the important denoising effects of temporal averaging. The authors believe, in addition to wellbeing and skin health monitoring, the designed sensor can particularly facilitate disease management in patients presenting diabetes mellitus, hypothyroidism, malnutrition, and atopic dermatitis

Synthetic photoplethysmography (PPG) of the radial artery through parallelized Monte Carlo and its correlation to body mass index (BMI)

Cardiovascular disease is one of the leading causes of death in the United States and obesity significantly increases the risk of cardiovascular disease. The measurement of blood pressure (BP) is critical in monitoring and managing cardiovascular disease hence new wearable devices are being developed to make BP more accessible to physicians and patients. Several wearables utilize photoplethysmography from the wrist vasculature to derive BP assessment although many of these devices are still at the experimental stage. With the ultimate goal of supporting instrument development, we have developed a model of the photoplethysmographic waveform derived from the radial artery at the volar surface of the wrist. To do so we have utilized the relation between vessel biomechanics through Finite Element Method and Monte Carlo light transport model. The model shows similar features to that seen in PPG waveform captured using an off the shelf device. We observe the influence of body mass index on the PPG signal. A degradation the PPG signal of up to 40% in AC to DC signal ratio was thus observed

Evaluating the Performance of Thermally and UV Aged Firefighters’ Protective Clothing Using both Destructive and Non-Destructive Methods

Firefighters’ protective clothing (e.g. coat and pants) are multi-layer ensembles consisting of an outer shell, moisture barrier, and thermal liner. Strict material performance and manufacturing conditions exist for new firefighter protective clothing constructions, but evaluation of in-use or worn protective clothing lacks these defined metrics. A need currently exists for the development of a quantitative, material-property based method of determining the remaining useful life of firefighters’ protective clothing. A non-destructive testing method is desirable due to the high replacement cost of firefighters’ protective clothing. Additionally, a non-destructive testing procedure developed in laboratory conditions could be adapted for field use and allow for material performance history tracking by individual firefighters. Guidelines and specific performance indicators could then be developed for a detailed garment retirement procedure for future implementation in fire departments. This information would be extremely useful to many firefighting departments in Canada and around the world. This study considered destructive and non-destructive textile testing of aged outer shell materials of firefighters’ clothing. Three types of outer-shell Kevlar®/PBI fabric types were examined and mechanical strength was used to evaluate remaining fabric performance following thermal and UV ageing procedures. Thermal exposures were chosen based on data obtained from thermogravimetric testing and exposure conditions faced by firefighters. A scanning electron microscope was used to evaluate microstructural changes in the fabrics following thermal and UV ageing procedures. A fiber microstructure crack-development process based on ageing was outlined using this information. Near infrared (NIR) reflectance readings were obtained through the use of a spectrophotometer and related to the remaining material strength of the aged fabrics. Different methods of interpreting NIR spectral results were compared. These included reflectance shifts, absorbance feature characteristic changes (e.g. feature area and peak prominence/width), and slope change based on a normalized-difference index method. Absorbance feature area and characteristic changes showed promise at explaining thermochemical changes in the specimens following ageing. However, the normalized-difference index slope changes showed the best potential for characterizing the remaining tensile strength for all three fabrics

Using Fluorescence – Polarization Endoscopy in Detection of Precancerous and Cancerous Lesions in Colon and Pancreatic Cancer

Colitis-associated cancer (CAC) arises from premalignant flat lesions of the colon, which are difficult to detect with current endoscopic screening approaches. We have developed a complementary fluorescence and polarization reporting strategy that combines the unique biochemical and physical properties of dysplasia and cancer for real time detection of these lesions. Utilizing a new thermoresponsive sol-gel formulation with targeted molecular probe allowed topical application and detection of precancerous and cancerous lesions during endoscopy. Incorporation of nanowire-filtered polarization imaging into NIR fluorescence endoscopy served as a validation strategy prior to obtaining biopsies. In order to reduce repeat surgeries arising from incomplete tumor resection, we demonstrated the efficacy of the targeted molecular probe towards margins of sporadic colorectal cancer (SCC). Fluorescence-polarization microscopy using circular polarized (CP) light served as a rapid, supplementary tool for assessment and validation of excised tissue to ensure complete tumor resection for examining tumor margins prior to H&E-based pathological diagnosis. We extended our platform towards non-invasive directed detection of pancreatic cancer utilizing fluorescence molecular tomography (FMT) and NIR laparoscopy using identified targeted molecular probe. We were able to non-invasively distinguished between pancreatitis and pancreatic cancer and guide pancreatic tumor resection using NIR laparoscopy