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An analytical solution of the bioheat model in a spherical tissue due to laser irradiation
摘要： This article studies an analytical approach associated with Laplace transform, experimental temperature data and a sequential concept over time to obtain the thermal damage and the temperature in living tissue due to laser irradiation. The effects of blood perfusion and the thermal relaxation time on the temperature of skin tissues and the resulting of thermal damage are investigated. The resulting of thermal damage to the tissue is assessed by the denatured protein range using the formulation of Arrhenius. The outcomes show that the hyperbolic bioheat model is reduced to the parabolic bioheat model when the relaxation time is close to zero. The numerical outcomes of thermal injuries and temperatures are graphically introduced. In conclusion, the comparison between the numerical computations and the existing experimental study displays that a current mathematical model is an effective tool for evaluating the biological heat transfer in biological tissues.
关键词： Laser irradiation,Laplace transforms,Thermal damages,Skin tissues
更新于2025-09-11 14:15:04
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Revascularization of Free Skin Grafts Overlying Modified Hughes Tarsoconjunctival Flaps Monitored Using Laser-Based Techniques
摘要： Purpose: It has recently been shown that the flap pedicle does not supply blood to a tarsoconjunctival graft in the modified Hughes procedure in patients. This raises questions concerning the rate of revascularization of the free skin graft commonly used to reconstruct the anterior lamella. The aim of this study was, thus, to monitor the course of revascularization in free skin grafts overlying modified Hughes tarsoconjunctival flaps, using laser-based techniques. Methods: Free skin grafts from the upper eyelid or upper arm in 9 patients were used to cover a tarsoconjunctival flap according to the modified Hughes procedure. Blood perfusion was monitored using laser speckle contrast imaging, and vascular reactivity was studied with laser Doppler velocimetry after heating the tissue to 44°C. Measurements were made at the time of surgery (baseline) and at 1, 3, 8, and 16 weeks postoperatively. Results: The gradual increase in perfusion of the free skin grafts during the healing process indicates revascularization. A slight increase in perfusion was seen already after 1 week. Perfusion reached 50% of the baseline after 3 weeks, and complete restoration of perfusion was seen after 8 weeks. The vascular function monitored with heat-induced hyperemia increased in a similar fashion. Conclusions: Full-thickness skin grafts revascularize within 3 to 8 weeks, despite overlying a tarsoconjunctival flap, which has recently been reported to be avascular. This provides further evidence that it should be possible to repair large eyelid defects using free full-thickness eyelid grafts.
关键词： laser Doppler velocimetry,revascularization,laser speckle contrast imaging,free skin grafts,modified Hughes tarsoconjunctival flaps
更新于2025-09-11 14:15:04
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MULTISPECTRAL IMAGING SYSTEM FOR QUANTITATIVE ASSESSMENT OF TRANSCUTANEOUS BLOOD OXYGEN SATURATION
摘要： This paper presents the use of Extended Modified Lambert Beer (EMLB) model for quantification of transcutaneous blood oxygen saturation (StO2) via a noninvasive approach. Continuous wave (CW) reflectance spectroscopy system is employed for measurement of intensity reflected from left index finger of an Asian nonsmoking volunteer at resting condition. Multispectral images captured in the wavelength range of 520 ? 600 nm at an interval of 10 nm are mathematically analyzed and fitted using the developed fitting algorithm to give the best estimation of StO2. The result from this preliminary study revealed a mean StO2 value of 75 ± 5% for the participating individual, which value agreed considerably well with that presented in previous works. This work concluded that the developed spectroscopy system and quantification technique can potentially be used as an alternative means to clinical assessment of wound healing progress.
关键词： Transcutaneous blood oxygen saturation,reflectance spectroscopy,Extended Modified Lambert Beer model,skin oximetry
更新于2025-09-11 14:15:04
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Simultaneous Blood Flow Measurement and Dermoscopy of Skin Lesions Using Dual-Mode Dermascope
摘要： Dermascopes are commonly utilized for the qualitative visual inspection of skin lesions. While automated image processing techniques and varied illumination strategies have been used to aid in structural analysis of lesions, robust quantification of functional information is largely unknown. To address this knowledge gap, we have developed a compact, handheld dermascope that enables real-time blood flow measurements of skin during conventional visual inspection. In-vitro characterization demonstrated that the dermascope is capable of quantifying changes in flow across a physiologically relevant range even when used in a handheld manner with clinic lighting and dermascope LEDs on. In a small pilot clinical study, we demonstrated the dermascope’s ability to detect flow differences between two distinct lesion types.
关键词： Skin Lesions,Laser Speckle Contrast Imaging,Functional Information,Dermoscopy,Blood Flow Measurement
更新于2025-09-11 14:15:04
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Objective determination of skin phototypes in healthy children by diffuse reflectance spectroscopy
摘要： Introduction: The clinical method of evaluating the color of the skin based on visual assessment is subjective and thus inaccurate. The objective determination of skin phototypes and levels of melanin in the skin is important for diagnosing the pigment disorders and also for adequate photoprotection. Diffuse re?ectance spectroscopy (DRS) is a non-invasive, precise and objective method for quantifying the melanin levels. Objective: The aim of this study is to assess the characteristic DRS spectrum of healthy skin in children and to detect the differences between them based on age, gender and skin phototype. Material and methods: Skin pigmentation was measured by DRS in 73 children patients with experimental spectrophotometer UM-ES600. The amount of melanin is quanti?ed from the obtained DRS spectra by proposed melanin quanti?cation angle α obtained by comparing the re?ectance properties of skin sample and universal depigmented sample (albino skin). Results: We evaluated spectroscopic characteristics of children’s healthy skin depending on age, gender and phototype. The value of melanin quanti?cation angle α grew proportionally from phototype I to phototype IV, without any correlation to age or gender. We con?rmed a clear association between clinical determination of Fitzpatrick’s skin phototypes and objective data collected by DRS and related angle α. Conclusions: Our proposed index quanti?es the difference in melanin levels in healthy children skin and also for different skin phototypes. The proposed method and melanin quanti?cation angle α can further be used for the objecti?cation of the progress of pigmentary diseases or for monitoring the effect of their therapy (Tab. 5, Fig. 4, Ref. 29). Text in PDF www.elis.sk.
关键词： melanin quanti?cation angle α,quanti?cation of skin melanin,diffuse re?ectance spectroscopy,skin phototypes
更新于2025-09-10 09:29:36
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Evaluation of penetration process into young and elderly skin using confocal Raman spectroscopy
摘要： Non-invasive in vivo human studies have always been of great importance owing to their advantages over the invasive studies. This research work also presents such a non-invasive study dealing with the penetration of two vitamin derivatives: retinyl acetate and alpha-tocopheryl acetate, into the stratum corneum of two groups of study participants categorized based on age as young (average age of 24.1 ± 3.3 years old) and elderly groups (average age of 68 ± 5.8 years old). According to the increase of age it is expected that intrinsic alterations may occur in the stratum corneum. Understanding these alterations is relevant to the knowledge of the differences between stratum corneum as a function of age-dependence thus, leading to the development of new specific products for ageing. The penetration of these derivatives was semi-quantitatively analyzed using confocal Raman spectroscopic technique with 3510 Skin Composition Analyzer (River Diagnostics, Rotterdam, The Netherlands) with a diode laser of 785 nm wavelength and 26 mW power. The analysis was done in the extended fingerprint region (1800 - 400 cm-1) for the stratum corneum region of the skin considering the depths from surface up to 24 μm. The results of this study clearly indicated that these two vitamin derivatives penetrated significantly into the stratum corneum of both study groups and their penetration was mainly affected by the composition of SC and their physico-chemical properties. The penetration profile of the alpha-tocopheryl acetate displays significant statistical difference (p < 0.05) between groups from surface up to 12 μm.
关键词： Non-invasive in vivo human skin study,Skin ageing,Vitamin penetration,Confocal Raman spectroscopy
更新于2025-09-10 09:29:36
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An empirical formula for temperature adjustment of complex permittivity of human skin in the terahertz frequencies
摘要： The Terahertz (THz) frequency region of the electromagnetic spectrum is defined as radiation of 0.1–10.0 (cid:1) 1012 Hz. There is limited knowledge of the skin absorption properties of THz, and there are no data on long-term exposure. Given the expanding security and industrial applications of THz, there will be an increase in the incidental and purposeful exposure of humans to this frequency range. Most incident THz radiation is absorbed within the first 0.3 mm of soft tissue; thus, there is a need to develop a reliable way of modeling the effect of this radiation on human skin. This paper analyzes the data available on the dielectric properties of skin in the THz range, with reference to differences at room and body temperature. The intent is to develop a technique for standardization of measurements obtained at diverse temperatures, allowing for a better comparison of different datasets. The adjustment is standardized to real (e0) and imaginary (e00) parts of complex permittivity (e(cid:3)) as described by Kaye and Laby [1995] and Lajevardipour et al. [2016].
关键词： terahertz,temperature,THz,skin,water content
更新于2025-09-10 09:29:36
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Water-based Terahertz Metamaterial for Skin Cancer Detection Application
摘要： We present a highly sensitive detection of skin cancer using a novel water-based (THz) metamaterial (MM) used semiconductor film. We apply the application of terahertz pulsed imaging (TPI) in reflection geometry for the study of skin tissue and related cancers. As a refractive index (RI) sensing application of the proposed device, there will be shown with placing different sensing materials in the biosensor design, the effective RI will also change that in turn leads to measuring the sensitivity of the biosensor to detect the normal skin and Basal Cell Carcinoma (BCC). The RI FOM value of the proposed device is much higher than for the sensor using semiconductor film, to detect biomarkers in the literature. Significantly, the sensitivity increases by about 117 um/RIU and the RI FOM increases by more than 20.53. This results from a combination of size-related factors, leading to field enhancement accompanying strong field localization. We observed the resonance-frequency shift of the THz MM following the RI changing of the detected skin. The dip reflectance resonance has a blue-shift for normal skin. Finally, we suggest that this water-based MM can be used to control of the gene expression. The advantage of our design depends on two factors. Firstly, we used the MM structure, which has micro-scale, and the smaller the size of the structure, the more sensitive to the changes in the RI. Secondly, we used water in our structure, which is very well-suited to the human body and are highly bio-absorbable and inexpensive which is abundantly found in nature.
关键词： bio-absorbable metamaterials,Skin Cancer detection,THz Metamaterials,Semiconductor Biosensor,Refractive Index Sensor,control of the gene expression
更新于2025-09-10 09:29:36
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[IEEE 2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan (SICE) - Nara (2018.9.11-2018.9.14)] 2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan (SICE) - Integrated Non-Invasive Vital Signs Monitoring System for Detecting Stress
摘要： Stress causes various types of physical disorders. When we experience stress, vital signs change as the sympathetic nervous system works to respond to stress and cope with the stressor. To prevent the disorders associated with stress, it is important to be able to measure multiple vital signs using a non-invasive method in order to detect the occurrences that cause these disorders in our daily lives. This study aimed to develop an integrated non-invasive vital signs monitoring system to measure vital signs such as heart rate variability and alterations in skin temperature, and to assess the ability of the system to detect stress. We developed an algorithm to measure pulse rate with high accuracy, on the basis of near infrared images of the human cheek, and we measured the nasal and forehead skin temperatures based on far infrared images. In the experiments, the system was demonstrated to calculate a pulse rate with sufficient accuracy. In addition, we conducted a stress detection experiment with four human participants, and we confirmed that the proposed integrated system could effectively detect stress, on the basis of the measured pulse rate and skin temperature, as stimulated by cold water applied to the wrist. In conclusion, the developed system was validated to be a feasible means of detecting stress.
关键词： Stress,Skin temperature,Non-invasive,Infrared,Pulse rate
更新于2025-09-10 09:29:36
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Microneedle-Assisted Topical Delivery of Photodynamically Active Mesoporous Formulation for Combination Therapy of Deep-Seated Melanoma
摘要： Topical treatment using photodynamic therapy (PDT) for many types of skin cancers has largely been limited by the inability of existing photosensitizers to penetrate into the deep skin tissue. To overcome these problems, we developed a mesoporous nanovehicle with dual loading of photosensitizers and clinically relevant drugs for combination therapy, while utilizing microneedle technology to facilitate their penetration into deep skin tissue. Sub-50 nm photodynamically active mesoporous organosilica nanoparticles were synthesized with photosensitizers covalently bonded to the silica matrix, which dramatically increased the quantum yield and photostability of these photosensitizers. The mesopores of the nanoparticles were further loaded with small-molecule inhibitors, i.e., dabrafenib and trametinib, that target the hyperactive mitogen-activated protein kinase (MAPK) pathway for melanoma treatment. As-prepared empty nanovehicle was cytocompatible with normal skin cells in the dark, while NIR-irradiated drug-loaded nanovehicle showed a synergistic killing effect on skin cancer cells mainly through reactive oxygen species and caspase-activated apoptosis. The nanovehicle could significantly inhibit the proliferation of tumor cells in a 3D spheroid model in vitro. Porcine skin fluorescence imaging demonstrated that microneedles could facilitate the penetration of nanovehicle across the epidermis layer of skin to reach deep-seated melanoma sites. Tumor regression studies in a xenografted melanoma mouse model confirmed superior therapeutic efficacy of the nanovehicle through combinational PDT and targeted therapy.
关键词： microneedle technology,mesoporous formulation,skin cancer,combination therapy,topical treatment
更新于2025-09-10 09:29:36