A battery-less implantable glucose sensor based on electrical impedance spectroscopy.

The ability to perform accurate continuous glucose monitoring without blood sampling has revolutionised the management of diabetes. Newer methods that can allow measurements during longer periods are necessary to substantially improve patients' quality of life. This paper presents an alternative method for glucose monitoring which is based on electrical impedance spectroscopy.

Skin hydration dynamics investigated by electrical impedance techniques in vivo and in vitro.

Skin is easily accessible for transdermal drug delivery and also attractive for biomarker sampling. These applications are strongly influenced by hydration where elevated hydration generally leads to increased skin permeability. Thus, favorable transdermal delivery and extraction conditions can be easily obtained by exploiting elevated skin hydration.

Dielectrical Properties of Living Epidermis and Dermis in the Frequency Range from 1 kHz to 1 MHz.

We determine the in-vivo dielectric properties-resistivity and relative permittivity-of living epidermis and dermis of human skin soaked with a physiological saline solution for one minute between 1 kHz and 1 MHz. This is done by fitting approximate analytical solutions of a mechanistic model for the transport of charges in these layers to a training set comprising impedance measurements at two depth settings on stripped skin on the volar forearm of 24 young subjects. Here, the depth settings are obtained by varying the voltage at a second inject on the electrical-impedance-spectroscopy probe.

A Batteryless Sensor ASIC for Implantable Bio-Impedance Applications.

The measurement of the biological tissue's electrical impedance is an active research field that has attracted a lot of attention during the last decades. Bio-impedances are closely related to a large variety of physiological conditions; therefore, they are useful for diagnosis and monitoring in many medical applications. Measuring living tissues, however, is a challenging task that poses countless technical and practical problems, in particular if the tissues need to be measured under the skin.

A methodology for extracting the electrical properties of human skin.

A methodology to determine dielectrical properties of human skin is presented and analyzed. In short, it is based on a mathematical model that considers the local transport of charge in the various layers of the skin, which is coupled with impedance measurements of both stripped and intact skin, an automated code generator, and an optimization algorithm. New resistivity and permittivity values for the stratum corneum soaked with physiological saline solution for 1 min and the viable skin beneath are obtained and expressed as easily accessible functions.

Electrical impedance spectroscopy and the diagnostic accuracy for malignant melanoma.

Background: The accuracy of diagnosis of skin cancer and especially of early malignant melanoma is most important to reduce its morbidity and mortality. Previous pilot studies using electrical impedance measurements indicate statistically significant accuracies for the detection of skin cancer.

Objectives: The aim of this study is to investigate the accuracy of electrical impedance spectra to distinguish between malignant melanoma and benign skin lesions using an automated classification algorithm.

Non-invasive bioimpedance of intact skin: mathematical modeling and experiments.

The functional integrity and pathology of the skin is reflected in its electrical impedance spectra. Non-invasive electrical impedance measurements of intact skin are dominated by the high impedic stratum corneum in low frequencies and with increasing frequency gradually comes to be dominated by viable skin. Models of this multi-layered organ can increase our understanding of the actual physical properties/dimensions and facilitate better diagnostics in certain applications.

Non-invasive and microinvasive electrical impedance spectra of skin cancer - a comparison between two techniques.

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.

Skin cancer identification using multifrequency electrical impedance--a potential screening tool.

Electrical bio-impedance can be used to assess skin cancers and other cutaneous lesions. The aim of this study was to distinguish skin cancer from benign nevi using multifrequency impedance spectra. Electrical impedance spectra of about 100 skin cancers and 511 benign nevi were measured.

Clinically normal atopic skin vs. non-atopic skin as seen through electrical impedance.

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.

Assessment of skin lesions and skin cancer using simple electrical impedance indices.

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 non- invasive 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.

Combined near-infrared spectroscopy and multifrequency bio-impedance investigation of skin alterations in diabetes patients based on multivariate analyses.

A group of 34 diabetic men, with different degrees of diabetes complications, including skin changes, were studied by near-infrared (NIR) spectroscopy and total body multi-frequency bio-impedance analyses (MFBIA-body). Skin reflectance spectra were measured with a fibre-optic probe in four locations (sites): hand, arm, leg and foot. As control subjects, a group of 23 healthy males were also measured.

The ability of betaine to reduce the irritating effects of detergents assessed visually, histologically and by bioengineering methods.

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.

The use of different concentrations of betaine as a reducing irritation agent in soaps monitored visually and non-invasively.

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.

Analysis of the O-wave in acute right ventricular apex impedance measurements with a standard pacing lead in animals.

Modern pacemakers (implantable devices used for maintaining an appropriate heart rate in patients) can use an intracardiac ventricular impedance signal for physiological cardiac stimulation control. Intracardiac ventricular impedance from nine animal subjects is analysed and presented (seven sheep: 49.0 +/- 6.

Betaine reduces the irritating effect of sodium lauryl sulfate on human oral mucosa in vivo.

Our aim was to evaluate whether betaine has a protective effect during exposure of the human oral mucosa in vivo to sodium lauryl sulfate (SLS) or cocoamidopropylbetaine (CAPB) as measured with a multifrequency electrical impedance spectrometer (EI). Both detergents were used at the concentration of 2.0% w/v with and without 4.

Variation of skin properties within human forearms demonstrated by non-invasive detection and multi-way analysis.

Background/aim: 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.

Electrical impedance measurements at different skin sites related to seasonal variations.

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.

Electrical bioimpedance related to structural differences and reactions in skin and oral mucosa.

Electrical bioimpedance can reflect structural and chemical changes of the skin and the oral mucosa in the beta-dispersion frequency range. From our measured multifrequency data set, four physically distinct indices have been formulated to distinguish the electrical properties for different anatomical locations and to detect different reactions and conditions of the skin and the oral mucosa. In comparison with the skin, the differences for various anatomical regions were greater in the oral cavity, which showed as well a different impedance pattern after irritant responses.

Inter- and intra-individual differences in human stratum corneum lipid content related to physical parameters of skin barrier function in vivo.

For a full understanding of the properties of the human skin barrier, physical macroscopic parameters of barrier function must be correlated to the structural organization of the barrier on a molecular level. This study was undertaken to relate differences in the relative composition of the three main lipid classes of human stratum corneum, i.e.

Electrical impedance of nodular basal cell carcinoma: a pilot study.

Background: Previously, we have explored the use of measurements of electrical impedance and devised 4 physically distinct indices named magnitude index (MIX), phase index, real part index and imaginary part index (IMIX) from the impedance data. Our results indicated that these indices could characterize contact reactions.

Objective: The goal of the present study was to use the electrical impedance method for the preoperative assessment of nodular basal cell carcinoma (BCC).

Electrical impedance and other physical parameters as related to lipid content of human stratum corneum.

Background/aims: In previous studies we have shown that variations in the properties of the stratum corneum are reflected by alterations in electrical impedance. The aim of this study was to explore the ability of the electrical impedance technique to detect changes in the lipid content of the stratum corneum, and to compare It with the other non-invasive methods, measurement of transepidermal water loss and of skin moisture.

Methods: Twenty-two healthy test subjects were recruited.

Volumetric determination of normal and scoliotic vertebral bodies.

A new method is presented for stereological evaluation of the volume of the vertebral body in vivo. The height of the vertebral body is measured at three standardised points on an anteroposterior radiograph and at two other points on a lateral one. The area of the body is also measured using a special grid superimposed on a CT scan from the middle part of the vertebra.