Electrical Bioimpedance Analysis for Evaluating the Effect of Pelotherapy on the Human Skin: Methodology and Experiments.

Background: Pelotherapy is the traditional procedure of applying curative muds on the skin's surface-shown to have a positive effect on the human body and cure illnesses. The effect of pelotherapy is complex, functioning through several mechanisms, and depends on the skin's functional condition. The current research objective was to develop a methodology and electrodes to assess the passage of the chemical and biologically active compounds of curative mud through human skin by performing electrical bioimpedance (EBI) analysis.

Derivation of Bioimpedance Model Data Utilizing a Compact Analyzer and Two Capacitive Electrodes: A Forearm Example.

The paper investigates the impacts of the selected electrical equivalent circuit model, measurement setup, and surrounding environment on the trustworthiness of electrical bioimpedance measurement and obtained model data in the human body. The influence of these constitutive components of the system on finding the model parameters is analyzed and illustrated with examples. The results based on experimental measurements on a forearm near the wrist are provided by employing the model, measurement setup, and novel 16-bit compact wireless impedance analyzer (CIA) according to the outcome of the analysis.

Methods for Detection of Bioimpedance Variations in Resource Constrained Environments.

Changes in a certain parameter are often a few magnitudes smaller than the base value of the parameter, specifying significant requirements for the dynamic range and noise levels of the measurement system. In case of electrical bioimpedance acquisition, the variations can be 1000 times smaller than the entire measured value. Synchronous or lock-in measurement of these variations is discussed in the current paper, and novel measurement solutions are presented.

Our Journal is Entering into its Second Decade.

The first issue of the saw the light in 2010 by the personal initiative of two men from the University of Oslo, Prof. Sverre Grimnes and Prof. Ørjan G.

Multichannel Electrical Impedance Spectroscopy Analyzer with Microfluidic Sensors.

Impedance spectroscopy is a common approach in assessing passive electrical properties of biological matter. However, several problems appear in microfluidic devices in connection with the requirement for high sensitivity of signal acquisition from small volume sensors. The developed compact and inexpensive analyzer provides impedance spectroscopy measurement from three sensors, both connected in direct and differential modes.

On the Selection of Excitation Signals for the Fast Spectroscopy of Electrical Bioimpedance.

Different excitation signals are applicable in the wideband impedance spectroscopy in general. However, in electrical bioimpedance (EBI) measurements, there are limitations that set specific demands on the properties of the excitation signals. This paper compares the efficiency of different excitation signals in a graspable presentation and gives recommendations for their use.

Crest factor optimization of the multisine waveform for bioimpedance spectroscopy.

The multisine excitation is widely used in impedance measurements to retain the advantages of the sine wave, while reducing the measurement time. Adding up sine waves increases the amplitude of the excitation signal, but, for the linearity assumption to be valid, the overall amplitude of the signal needs to be kept low. Thus, the crest factor (CF) of the excitation signal must be minimized.

Broadband discrete-level excitations for improved extraction of information in bioimpedance measurements.

The implementation of bioimpedance-based methods in implantable and wearable medical devices requires simple, cheap and low energy consuming measurement settings for enabling impedance spectroscopy at a wide range of frequencies. In the present paper, such a wideband bioimpedance measurement method is discussed, which embodies two-channel impedance measurement for monitoring of the frequency-dependent phase shift between the channels (phase spectrum). In addition, the improved resolution is achieved by employing comparative measurements by introducing the predetermined reference impedance into one of the measurement channels.

Wearable data acquisition system of multimodal physiological signals for personal health care.

The paper proposes a wearable multimodal data acquisition system for biological signals. The system enables logging of electrical bioimpedance signals from multiple electrodes, electrocardiographic signals (ECG), acceleration signals from multiple locations, and spirometric data from a moving object. Later it will be used to conduct field measurements for characterizing health of the object under investigation.

Wearable system for non-invasive and continuous monitoring central aortic pressure curve and augmentation index.

The paper presents a non-invasive method and system for a long-term and continuous monitoring of the central aortic pressure (CAP) waveform and the augmentation index (AI). The CAP curve is estimated from the measured radial electrical bio-impedance (EBI) using spectral domain transfer functions (TF), which are established on the basis of data analysis during clinical experiments. Experiments were carried out on 3 volunteers by now.

Binary signals in impedance spectroscopy.

Using of binary waveforms in the fast impedance spectroscopy of biological objects is discussed in the paper. There is shown that the energy of binary waveforms can be concentrated onto selected separate frequencies. We can optimize the binary excitation waveform depending on the shape of frequency response of the impedance under study to maximize the levels of signal components with certain selected frequencies.

Improvements in design of spectra of multisine and binary excitation signals for multi-frequency bioimpedance measurement.

The paper discusses the usability of multi-frequency binary waveforms for broadband excitation in fast measurements of impedance spectrum of biological objects. It is shown that up to 70% of the energy of the amplitude spectrum of such two-level binary signals can be concentrated into the selected separate frequencies. The levels of selected frequency components are controllable in tens and hundreds of times.

Online tissue discrimination for transcutaneous needle guidance applications using broadband impedance spectroscopy.

This paper reports on a novel system architecture for measuring impedance spectra of a biological tissue close to the tip of a hollow needle. The measurement is performed online using fast broadband chirp signals. The time domain measurement raw data are transformed into the transfer function of the tissue in frequency domain.

Intracardiac electrical bioimpedance as a basis for controlling of pacing rate limits.

Intracardiac impedance can provide real-time hemodynamic information to automatically control the lower and upper rate limits of a rate-adaptive pacemaker. It is necessary to overcome a number of technical challenges to accomplish this within the constraints of an implantable device.