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  • 1. Aberg, P.
    et al.
    Geladi, P.
    Nicander, I, .
    Ollmar, Stig
    Variation of skin properties within human forearms demonstrated by non-invasive detection and multi-way analysis2002In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 8, no 3, p. 194-201Article in journal (Refereed)
    Abstract [en]

    Background: It is known that the properties of human skin vary locally. The purpose of this study was to investigate the properties of human volar forearms even further using advanced non-invasive techniques and numerical methods. Methods: The skin properties of human volar forearms were investigated using measurements of trans epidermal water loss and multifrequency electrical impedance. Eight sites on the forearms of 27 healthy volunteers were measured. The sites were oriented as squares, four sites on both left and right forearm, approximately 40-50 mm apart. Results: Analysis of variance showed significant differences for epidermal water loss (P < 0.01) and the skin impedance (P < 0.001) between the inner and outer sides of the arms. Additionally, parallel factor analysis of the full skin impedance spectra also showed that there are systematic differences between right and left arm (P < 0.01). Conclusions: It is crucial to design skin studies carefully in order to minimise the effects of the local skin properties of human skin.

  • 2. Aberg, P.
    et al.
    Geladi, P.
    Nicander, I.
    Hansson, J.
    Holmgren, U, .
    Ollmar, Stig
    Non-invasive and microinvasive electrical impedance spectra of skin cancer - a comparison between two techniques2005In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 11, no 4, p. 281-286Article in journal (Refereed)
    Abstract [en]

    Background/purpose: Bio-electrical impedance spectra of skin cancer and other lesions can be assessed using both regular non-invasive probes and a novel type of microinvasive electrode system with a surface furnished with tiny spikes that penetrate stratum corneum. The aim of the study was to compare the accuracy of detection for various types of skin cancer using impedance spectra measured with these two different electrode systems in an objective way without optimising the power of discrimination. Methods: Impedance spectra of 99 benign nevi, 28 basal cell carcinomas (BCC), and 13 malignant melanomas (MM) were measured using the two electrode systems. Classification of the lesions was made using Fisher's linear discriminant, and the sensitivities and specificities of the techniques were estimated using cross-validation. Results: The best separation between nevi and BCC was achieved using the regular non-invasive probe (96% sensitivity and 86% specificity), whereas the best separation between nevi and MM was achieved using the microinvasive electrodes (92% sensitivity and 80% specificity). Conclusions: Our results indicate that the choice of electrode system is application dependent.

  • 3. Aberg, P.
    et al.
    Nicander, I, .
    Holmgren, U.
    Geladi, P.
    Ollmar, Stig
    Assessment of skin lesions and skin cancer using simple electrical impedance indices2003In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 9, no 3, p. 257-261Article in journal (Refereed)
    Abstract [en]

    Background/aims: Purpose of this investigation was to assess benign pigmented cellular nevus (BEN), basal cell carcinoma (BCC), dermatofibroma (DER), dysplastic nevus (DYS), and seborrheic keratoses (SEB) using in vivo noninvasive electrical impedance technique. Methods: Electrical impedance was measured at 258 BEN, 34 BCC, 17 DER, 35 DYS, and 26 SEB lesions. Controls were measured at healthy skin close to the lesions. The impedance was measured between 1 kHz and 1 MHz at five depth settings. After the impedance measurements the lesions were histopathologically diagnosed. The impedance spectra were parameterized to four indices prior to the statistical analysis of the data. Results: There were significant differences between the lesions and their controls for BEN (P<0.001), BCC (P<0.001), DYS (P<0.01), and SEB(P<0.01). Conclusions: There are clear statistical differences between impedance of common lesions and control skin. With some further developments, the impedance technique can be useful as a diagnostic decision support tool for skin cancer assessment.

  • 4. Dancila, D.
    et al.
    Augustine, R.
    Töpfer, Fritzi
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Hu, X.
    Emtestam, L.
    Tenerz, L.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Rydberg, A.
    Millimeter wave silicon micromachined waveguide probe as an aid for skin diagnosis - results of measurements on phantom material with varied water content2014In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 20, no 1, p. 116-123Article in journal (Refereed)
    Abstract [en]

    Background: More than 2 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. Early detection of cancer usually results in less extensive treatment and better outcome for the patient. Millimeter wave silicon micromachined waveguide probe is foreseen as an aid for skin diagnosis, which is currently based on visual inspection followed by biopsy, in cases where the macroscopical picture raises suspicion of malignancy. Aims: Demonstration of the discrimination potential of tissues of different water content using a novel micromachined silicon waveguide probe. Secondarily, the silicon probe miniaturization till an inspection area of 600 × 200 μm2, representing a drastic reduction by 96.3% of the probing area, in comparison with a conventional WR-10 waveguide. The high planar resolution is required for histology and early-state skin-cancer detection. Material and methods: To evaluate the probe three phantoms with different water contents, i.e. 50%, 75% and 95%, mimicking dielectric properties of human skin were characterized in the frequency range of 95-105 GHz. The complex permittivity values of the skin are obtained from the variation in frequency and amplitude of the reflection coefficient (S11), measured with a Vector Network Analyzer (VNA), by comparison with finite elements simulations of the measurement set-up, using the commercially available software, HFSS. The expected frequency variation is calculated with HFSS and is based on extrapolated complex permittivities, using one relaxation Debye model from permittivity measurements obtained using the Agilent probe. Results: Millimeter wave reflection measurements were performed using the probe in the frequency range of 95-105 GHz with three phantoms materials and air. Intermediate measurement results are in good agreement with HFSS simulations, based on the extrapolated complex permittivity. The resonance frequency lowers, from the idle situation when it is probing air, respectively by 0.7, 1.2 and 4.26 GHz when a phantom material of 50%, 75% and 95% water content is measured. Discussion: The results of the measurements in our laboratory set-up with three different phantoms indicate that the probe may be able to discriminate between normal and pathological skin tissue, improving the spatial resolution in histology and on skin measurements, due to the highly reduced area of probing. Conclusion: The probe has the potential to discriminate between normal and pathological skin tissue. Further, improved information, compared to the optical histological inspection can be obtained, i.e. the complex permittivity characterization is obtained with a high resolution, due to the highly reduced measurement area of the probe tip.

  • 5. Nicander, I.
    et al.
    Aberg, P.
    Ollmar, Stig
    The use of different concentrations of betaine as a reducing irritation agent in soaps monitored visually and non-invasively2003In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 9, no 1, p. 43-49Article in journal (Refereed)
    Abstract [en]

    Background/aims: Products containing detergents can damage the skin and give rise to irritant contact dermatitis. Therefore, attempts have been made to find less irritating detergents as well as substances decreasing undesired side-effects of detergents, and a novel approach is offered by betaine. The aim of the study has been to determine the irritating properties of some liquid soaps for personal hygiene and to map the effect of different concentrations of betaine using electrical impedance, trans -epidermal water loss and visual inspection. Methods: Twenty-eight healthy subjects were patch tested with different commercial soaps with and without betaine and sodium lauryl sulphate on both volar forearms for 24 h. A site with distilled water and an unoccluded area were used as references. Responses of the skin reactions were evaluated by visual inspection and by measuring trans-epidermal water loss and electrical impedance before application and 24 h after removal of the chambers. Results/conclusions: Significant skin reactions were found for all soaps tested but the soaps containing betaine were the least irritating. However, the skin irritation did not decrease with increasing concentrations of betaine in the tested range. On the whole the differences between the products were not large. The non-invasive methods used were more sensitive than visual assessment for evaluation of invisible or barely visible skin responses.

  • 6. Nicander, I.
    et al.
    Ollmar, Stig
    Clinically normal atopic skin vs. non-atopic skin as seen through electrical impedance2004In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 10, no 3, p. 178-183Article in journal (Refereed)
    Abstract [en]

    Background/aims: In an earlier study, we have shown that the electrical impedance (IMP) is dependent on the lipid content of the stratum corneum as studied by lipid extraction. Therefore, we now employ the IMP technique to compare the properties of clinically normal atopic skin with that of non-atopic skin. We looked at the same time at concomitant alterations in transepidermal water loss (TEWL) and skin moisture results. Methods: Twenty-two healthy participants and 26 patients with atopic dermatitis were recruited. One test site on each volar forearm was used in the test procedure, of cyclohexane swabbing, skin stripping, and lipid extraction using a mixture of hexane:isopropanol. Responses were evaluated by measuring TEWL, skin moisture using electrical capacitance, and finally IMP spectroscopy in the frequency range 1 kHz to 1 MHz before the start of the study, after each step of the test procedure, and also during a 2 weeks recovery period. Results: Only the IMP results showed significant changes between baseline values of clinically normal atopic skin and healthy skin. Furthermore, IMP and TEWL showed significantly larger reactivity for the atopic group after the skin stripping procedure, and IMP after lipid extraction as well. Conclusion: Our results show that IMP is a useful method for detection of changes in the lipid content of the stratum corneum by discriminating healthy looking atopic skin from healthy control skin, and to detect changes in reactivity between the two groups.

  • 7. Nicander, I.
    et al.
    Ollmar, Stig
    Electrical impedance measurements at different skin sites related to seasonal variations2000In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 6, no 2, p. 81-86Article in journal (Refereed)
    Abstract [en]

    Background/aims: In a previous study we mapped differences in electrical impedance between different anatomical locations related to age and sex. Now we employ the electrical impedance technique for studying the seasonal variations for the same skin sites. Method: The investigation was performed on 48 healthy volunteers divided into two groups on the basis of sex. Readings of electrical impedance were taken from ten different body locations at each of the four seasons during one year. Electrical impedance spectra were measured in the frequency range 1 kHz to 1 MHz, acid four impedance indices based on the complex impedance values at 20 kHz and 500 kHz were calculated. Results: The baseline values varied from one site to another and increased significantly for most sites from the winter to the summer, while the changes from October to March were negligible. Using ANOVA, the seasonal variation was found to be a more important factor than sex. Conclusions: Our results suggest that seasonal variations for different skin sites should be taken into consideration when using the electrical impedance technique.

  • 8. Nicander, I.
    et al.
    Rantanen, I.
    Rozell, B. L.
    Söderling, E.
    Ollmar, Stig
    The ability of betaine to reduce the irritating effects of detergents assessed visually, histologically and by bioengineering methods2003In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 9, no 1, p. 50-58Article in journal (Refereed)
    Abstract [en]

    Background/aims: A novel approach for reducing the undesired irritating properties of detergents on skin might be offered by betaine, which is a natural product derived from the sugar beet. The aim of the study was to explore the ability of betaine to reduce the irritating effects of two surfactants, sodium lauryl sulphate (SLS) and cocoamidopropylbetaine (CAPB). For evaluation of changes in skin reactions visual scoring, electrical impedance, transepidermal water loss and histology were used. Methods: Twenty-one healthy subjects were patch tested for 24 h with SLS and CAPB alone and together with betaine, betaine alone, and the two controls distilled water and an unoccluded test site on both volar forearms. Responses were evaluated by measuring electrical impedance and transepidermal water loss before exposure and 24 h after the removal of the test substances, and also by visual inspection and histology. The electrical impedance device enables measurements at 31 frequencies and relevant information was extracted from the spectra using four indices. Results: CAPB was found to be less irritating than SLS. The used detergents gave rise to distinctive impedance patterns also reflected by different types of histopathological skin responses. After the adding of betaine, the irritant reaction decreased for both detergents. Conclusions: Betaine is a promising ingredient to reduce the side effects of detergents and electrical impedance is a suitable tool both to quantify the degree of irritation as well as to differentiate between various types of reactions.

  • 9.
    Skedung, Lisa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Tech Res Inst Sweden.
    Ringstad, Lovisa
    YKI Institute for Surface Chemistry.
    Norin, Izabela
    ACO HUD Nordic AB.
    Rutland, Mark
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Tech Res Inst Sweden.
    Tactile friction of topical formulations2016In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 22, no 1, p. 46-54Article in journal (Refereed)
    Abstract [en]

    Background: The tactile perception is essential for all types of topical formulations (cosmetic, pharmaceutical, medical device) and the possibility to predict the sensorial response by using instrumental methods instead of sensory testing would save time and cost at an early stage product development. Here, we report on an instrumental evaluation method using tactile friction measurements to estimate perceptual attributes of topical formulations. Methods: Friction was measured between an index finger and an artificial skin substrate after application of formulations using a force sensor. Both model formulations of liquid crystalline phase structures with significantly different tactile properties, as well as commercial pharmaceutical moisturizing creams being more tactile-similar, were investigated. Friction coefficients were calculated as the ratio of the friction force to the applied load. The structures of the model formulations and phase transitions as a result of water evaporation were identified using optical microscopy. Results: The friction device could distinguish friction coefficients between the phase structures, as well as the commercial creams after spreading and absorption into the substrate. In addition, phase transitions resulting in alterations in the feel of the formulations could be detected. A correlation was established between skin hydration and friction coefficient, where hydrated skin gave rise to higher friction. Also a link between skin smoothening and finger friction was established for the commercial moisturizing creams, although further investigations are needed to analyse this and correlations with other sensorial attributes in more detail. Conclusion: The present investigation shows that tactile friction measurements have potential as an alternative or complement in the evaluation of perception of topical formulations.

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