The Howland current pump is a popular bioelectrical circuit, useful for delivering precise electrical currents. In applications requiring high precision delivery of alternating to biological loads, the output impedance critical figure merit that limits delivered when load changes. We explain minimum operational amplifier requirements meet target over wide bandwidth. also discuss effective compensation strategies achieving stability without sacrificing frequency impedance. A source suitable...

Electrode properties are key to the quality of measured biopotential signals. Ubiquitous health care systems require long-term monitoring signals from normal volunteers and patients in home or hospital environments. In these settings it is appropriate use dry textile electrode networks for purposes, rather than gel saline-sponge skin interfaces used with Ag/AgCl electrodes. this study, we report performance test results two different electrospun conductive nanofiber webs, three metal plated...

Transcranial direct current stimulation (tDCS) is an emerging neuromodulation therapy that has been experimentally determined to affect a wide range of behaviors and diseases ranging from motor, cognitive, memory processes depression pain syndromes. The effects tDCS may be inhibitory or excitatory, depending on the relative polarities electrodes their proximity different brain structures. This distinction believed relate interaction flow with activation thresholds neural complexes. currents...

In magnetic resonance electrical impedance tomography (MREIT), we measure the induced flux density inside an object subject to externally injected current. This is contaminated with noise, which ultimately limits quality of reconstructed conductivity and current images. By analysing experimentally verifying amount noise in images gathered from two MREIT systems, found that a carefully designed study will be able reduce levels below 0.25 0.05 nT at main field strengths 3 11 T, respectively,...

We present the first in vivo images of anisotropic conductivity distribution human head, measured at a frequency approximately 10 Hz. used magnetic resonance electrical impedance tomography techniques to encode phase changes caused by current flow within head via two independent electrode pairs. These results were then combined with diffusion tensor imaging data reconstruct full distributions 5-mm-thick slices brains participants. Conductivity values recovered this paper broadly consistent...

Introduction Magnetic resonance-based electrical conductivity imaging offers a promising new contrast mechanism to enhance disease diagnosis. Conductivity tensor (CTI) combines data from MR diffusion microstructure reconstruct electrodeless low-frequency images. However, different methods rely on varying models and parameters, leading divergent tissue estimates. This study investigates the variability in predictions across evaluates their alignment with experimental observations. Methods We...

The electrical properties of biological tissues can be described by a complex tensor comprising simple expression the effective admittivity. admittivities depend on scale, applied frequency, proportions extra- and intracellular fluids, membrane structures. admittivity spectra tissue used as means characterizing structural information relating to cell suspensions, therefore measuring frequency-dependent conductivity is important for understanding tissue’s physiological conditions structure....

Objective. In this study, we determined efficient head model sizes relative to predicted current densities in transcranial direct stimulation (tDCS). Approach. Efficiency measures were defined based on a finite element (FE) simulations performed using nine human models derived from single MRI data set, having extents varying 60%–100% of the original axial range. Eleven tissue types, including anisotropic white matter, and three electrode montages (T7–T8, F3-right supraorbital, Cz–Oz) used...

Efficient connection of multiple electrodes to the body for impedance measurement and voltage monitoring applications is critical importance quality practicality. Electrical tomography (EIT) experiments have generally required a cumbersome procedure attach needed in EIT. Once placed, these must then maintain good contact with skin during measurements that may last several hours. There usually also need manage wires run between EIT system. These problems become more severe as number...

Intraventricular hemorrhage (IVH) is a common occurrence in the days immediately after premature birth. It has been correlated with outcomes such as periventricular leukomalacia (PVL), cerebral palsy and developmental delay. The causes evolution of IVH are unclear; it associated fluctuations blood pressure, damage to subventricular zone seizures. At present, ultrasound most commonly used method for detection IVH, but retrospectively. Without presence adequate therapies avert use continuous...

A prototype electrical impedance tomography system was evaluated prior to its use for the detection of intraperitoneal bleeding, with assistance patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The sensitive enough detect small amounts fluid appearing in subtractive images over short time periods. Uniform sensitivity blood anywhere within abdominal cavity produced using a post-reconstructive filter that corrected changes apparent resistivity anomalies their radial...

Magnetic resonance electrical impedance tomography (MREIT) has the potential to provide conductivity and current density images with high spatial resolution accuracy. Recent experimental studies at a field strength of 3 T showed that may be similar conventional MR as long enough is injected, least 20 mA when object being imaged size human head. To apply MREIT technique image small changes using less injection current, we performed 11 strength, where noise levels in measured magnetic flux...

Electrical impedance tomography (EIT) is particularly well-suited to applications where its portability, rapid acquisition speed and sensitivity give it a practical advantage over other monitoring or imaging systems. An EIT system's patient interface can potentially be adapted match the target environment, thereby increase utility. It may thus appropriate use different electrode positions from those conventionally used in these cases. One application that require this of on emergency...

Background . Phosphene generation is an objective physical measure of potential transcranial alternating current stimulation (tACS) biological side effects. Interpretations from phosphene analysis can serve as a first step in understanding underlying mechanisms tACS healthy human subjects and assist validation computational models. Objective/Hypothesis This preliminary study introduces tests methods to analyze predicted occurrence using head models constructed recipients against verbal...

Magnetic resonance electrical impedance tomography (MREIT) sequences typically use conventional spin or gradient echo-based acquisition methods for reconstruction of conductivity and current density maps. Use MREIT in functional electroporation studies requires higher temporal resolution faster sequences. Here, single multishot echo planar imaging (EPI) based were evaluated to see whether high-quality phase data could be obtained rapid density, conductivity, electric fields.A gel phantom...

The electrical impedance tomography (EIT) image reconstruction problem is ill posed and spatially variant. Because of the problem's ill-posed nature, small amounts measurement noise can corrupt reconstructed images. must be regularized to reduce artifacts. In this paper, we focus on variant characteristics problem. Correcting errors due spatial variance should improve accuracy. present methods normalize by equalizing point spread function (PSF). order equalize PSF, used blurring properties...