Measurement of the electrical properties of human skin and the variation among subjects with certain skin conditions

Abstract

In this study the dielectric properties are reported for human skin tissues over the frequency range 1-450 MHz at 36 degrees C. Healthy volunteers, collagen disease patients and dialysis patients are studied in order to investigate, primarily, the variability among (1) different regions of one individual, (2) the same region among different individuals and (3) skin conditions due to diseases. Considerable differences exist among the skin dielectric properties obtained from different regions of one individual body. Although region dependence is observed, larger variability is found even in the same skin region among individuals.

Epidermal Differential Impedance Sensor for Conformal Skin Hydration Monitoring

“…Furthermore, at a fixed hydration level of 90, the impedance amplitude decreases from 558 kX at 15 kHz to 332 kX at 95 kHz, while the phase increases by 0.36 rad over this same RF range. These trends arise from the frequency dependence of the conductivity and permittivity of the skin due mostly to expected effects in aqueous electrolyte solutions [31][32][33][34]. The result is increased changes in impedance with hydration levels at low measurement frequencies (e.g.…”

Reduction of a High-field Dielectric Artifact with Homemade Gel

“…1,3,5 Other causal factors include interference related to shortened radiofrequency (RF) wave on a high-tesla magneticˆeld, electromagnetic wave impedance mismatching of the air-to-tissue interface at the surface of an object, and multiple current-carrying elements in RF coils. 1,[6][7][8] Shortened RF wavelengths cause various problems in the high-tesla magnetiĉ eld because changes in wavelength are inversely proportional to the strength of B0. Shortened wavelength would be partly re‰ected, partly transmitted, and partly absorbed at an object's surface.…”

“…Shortened wavelength would be partly re‰ected, partly transmitted, and partly absorbed at an object's surface. 6 These phenomena also cause inhomogeneous B1 eld distribution. Several methods to improve B1 inhomogeneity have been reported and include use of a novel RF transmitter coil system, modiˆed RF pulse sequences, adequate imaging processing after examination, and dielectric material around objects during examination.…”

“…2,3,7,8 We have reported an original method to develop a dielectric-equivalent gel with better impedance matching for human skin. 6,7 Use of the gel between an object and the receiver coil during MR scanning can improve B1 inhomogeneity in a high-tesla magneticˆeld by reducing the interference and re‰ection of RF waves at the object's surface. In this study, we assessed the eŠect of our home-made gel pad using a plastic-bottle phantom on a 3T MR system.…”

An assessment of the performance of grip enhancing agents used in sports applications

“…This number is produced from taking the moisture measurements of 300 people, therefore a measurement of 50, is equivalent to the average capacitance reading from the sample of 300 people. The dielectric constant of skin has been recorded to be 28 -48 [13] (however this depends on the depth of measurement). In this experiment if the layer of gripping agent is substantially thin and also has a much lower dielectric constant than the skin, it can be assumed that the device is measuring the capacitance of the skin.…”