Capacitive Properties of Body Tissues

Schwan, Herman P.; Kay, Calvin F.

doi:10.1161/01.res.5.4.439

Cited by 76 publications

(38 citation statements)

References 3 publications

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“…These currents will, in general, consist of both conductive and capacitive (displacement) components. For living tissues at 60-Hz, the capacitive component is small [Schwan and Kay, 1957;Schwan, 19631 and will be neglected here. For conducting models, which have much smaller dielectric constants, the capacitive current is negligible.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Comparison of the coupling of grounded humans, swine and rats to vertical, 60‐Hz electric fields

Kaune¹,

Phillips²

1980

Bioelectromagnetics

106

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Published and new data for grounded humans, swine, and rats exposed to vertical, 60-Hz electric fields are used to determine field strengths at the surfaces of the bodies and average components of induced-current density along the axes of the bodies. At the tops of the bodies, surface electric fields are increased (enhanced) over the unperturbed field strength present before the subjects entered the field by factors of 17, 7, and 4 for humans, swine, and rats, respectively. For an unperturbed field strength of 10 kV/m, average induced axial current densities in the neck, chest, abdomen, and feet are: 550, 190 250, and 200 nA/cm2, respectively, for humans; 40, 13, 20, and 1100 nA/cm2, respectively, for swine; and 28, 16, 2, and 1400 nA/cm2, respectively, for rats. These data are used to show that the actual electric fields experienced by animals depend strongly on the shape of the body and its orientation relative to the electric field and ground plane. This fact must be taken into account if biological data obtained with laboratory animals are to be used for the assessment of possible hazards to humans exposed to 60-Hz electric fields.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Comparison of the coupling of grounded humans, swine and rats to vertical, 60‐Hz electric fields

Kaune¹,

Phillips²

1980

Bioelectromagnetics

106

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“…Observations were made on the conductance and capacitance across the pancreas, secreting in response to single i. small fraction of the total impedance at this frequency (Schwan & Kay, 1957) the results will be described in terms of conductance. The rate of secretion was determined by recording the interval between drops of juice.…”

Section: Resultsmentioning

confidence: 99%

The electrical properties of resting and secreting pancreas

Clark¹,

Greenwell²,

Harper³

et al. 1967

The Journal of Physiology

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SUMMARY1. The electrical properties of the resting and stimulated pancreas have been studied in the anaesthetized cat. There is an inverse relationship between the frequency ofapplied alternating current and the resistivity and dielectric constant of the resting pancreas. The resistivity is also affected by the fat content of the gland. The impedance locus of the pancreas is similar to that of other tissues.2. On intravenous injection of secretin there is a brief increase, followed by a more marked decrease, in conductance and capacitance of the pancreas. The phase of decreased conductance is related to the flow of pancreatic juice. The decrease in conductance and the flow rate can be characterized by two closely related empirical equations.3. During secretin stimulation the sodium concentration in pancreatic tissue increases, and the potassium concentration falls.4. It is tentatively suggested that the decreased conductance across the secreting gland is mostly due to swelling of the secretory cells and to a minor degree is the result of changes in the composition of the secretion in the pancreatic ducts.5. In the anaesthetized cat the mean half life of the secretory action of secretin is 199 sec.

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“…Laplace's equation provides a quasi-static approximation of Poisson's equation; this assumes negligible capacitive effects in bodily tissue, as demonstrated experimentally by Schwan and Kay [11] at frequencies below 1 kHz. We use Dirichlet boundary conditions to set the voltages at active electrode surfaces and a Neumann boundary condition to prevent current from leaving the volume conductor:…”

Section: Simulationsmentioning

confidence: 96%

“…Each stimulation pattern in the experimental dataset was simulated, yielding a voltage distribution throughout the volume conductor. As justified by Schwan and Kay [11] and Ladenbauer [8], we only simulate the effect of the stimulus' pulse at its peak. Fig.…”

Section: Simulationsmentioning

confidence: 99%

Modeling motor responses of paraplegics under epidural spinal cord stimulation

Feldman

Burdick

2017

2017 8th International IEEE/EMBS Conference on Neural Engineering (NER)

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Abstract-Epidural spinal cord stimulation (SCS) is a promising therapy for spinal cord injury (SCI). This paper combines experimental data from epidurally-stimulated human paraplegic patients with computational models of SCS to identify the electric field features correlated with the patients' ability to stand. We locate the spinal cord regions most critical to stimulated standing and find that the most informative stimulating features agree with results from nerve fiber theory. Further applications of our work include developing algorithms to optimize stimulation configurations for SCI patients, determining optimal electrode placement, and considering novel electrode array designs.

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Capacitive Properties of Body Tissues

Cited by 76 publications

References 3 publications

Comparison of the coupling of grounded humans, swine and rats to vertical, 60‐Hz electric fields

Comparison of the coupling of grounded humans, swine and rats to vertical, 60‐Hz electric fields

The electrical properties of resting and secreting pancreas

Modeling motor responses of paraplegics under epidural spinal cord stimulation

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