Analysis of current density and specific absorption rate in biological tissue surrounding an air-core type of transcutaneous transformer for an artificial heart.

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference · 2006 · Mixed · Low evidence

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MixedLow evidencePaper 3478

Study snapshot

PublicationConference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference · 2006

Study typeengineering

Reported directionMixed

Evidence ratingLow

Abstract

This paper reports on the specific absorption rate (SAR) and the current density analysis of biological tissue surrounding an air-core type of transcutaneous transformer for an artificial heart. The electromagnetic field in the biological tissue surrounding the transformer was analyzed by the transmission-line modeling method, and the SAR and current density as a function of frequency (200k-1 MHz) for a transcutaneous transmission of 20 W were calculated. The model's biological tissue has three layers including the skin, fat and muscle. As a result, the SAR in the vicinity of the transformer is sufficiently small and the normalized SAR value, which is divided by the ICNIRP's basic restriction, is 7 x 10(-3) or less. On the contrary, the current density is slightly in excess of the ICNIRP's basic restrictions as the frequency falls and the output voltage rises. Normalized current density is from 0.2 to 1.2. In addition, the layer in which the current's density is maximized depends on the frequency, the muscle in the low frequency (<700 kHz) and the skin in the high frequency (>700 kHz). The result shows that precision analysis taking into account the biological properties is very important for developing the transcutaneous transformer for TAH.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionmixed

PopulationNot supplied

Sample sizeNot supplied

ExposureELF

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Using transmission-line modeling for a 20 W transcutaneous transformer (200 kHz–1 MHz) with a 3-layer tissue model (skin, fat, muscle), SAR near the transformer was reported as sufficiently small; normalized SAR (relative to ICNIRP basic restriction) was ≤7×10^-3. In contrast, current density slightly exceeded ICNIRP basic restrictions at lower frequencies and higher output voltages, with normalized current density ranging from 0.2 to 1.2; the tissue layer with maximum current density depended on frequency (muscle <700 kHz; skin >700 kHz).

Outcomes measured

specific absorption rate (SAR)
current density
comparison to ICNIRP basic restrictions

Limitations

Modeling/simulation study (transmission-line modeling) rather than measurements in humans or animals
No sample size or empirical exposure measurements reported in abstract
Specific SAR and current density absolute values not provided in abstract (only normalized values/ranges)

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "ELF",
    "source": "transcutaneous transformer (artificial heart)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "specific absorption rate (SAR)",
    "current density",
    "comparison to ICNIRP basic restrictions"
  ],
  "main_findings": "Using transmission-line modeling for a 20 W transcutaneous transformer (200 kHz–1 MHz) with a 3-layer tissue model (skin, fat, muscle), SAR near the transformer was reported as sufficiently small; normalized SAR (relative to ICNIRP basic restriction) was ≤7×10^-3. In contrast, current density slightly exceeded ICNIRP basic restrictions at lower frequencies and higher output voltages, with normalized current density ranging from 0.2 to 1.2; the tissue layer with maximum current density depended on frequency (muscle <700 kHz; skin >700 kHz).",
  "effect_direction": "mixed",
  "limitations": [
    "Modeling/simulation study (transmission-line modeling) rather than measurements in humans or animals",
    "No sample size or empirical exposure measurements reported in abstract",
    "Specific SAR and current density absolute values not provided in abstract (only normalized values/ranges)"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "transcutaneous transformer",
    "artificial heart",
    "TAH",
    "specific absorption rate",
    "SAR",
    "current density",
    "ICNIRP",
    "transmission-line modeling",
    "200 kHz",
    "1 MHz",
    "skin",
    "fat",
    "muscle"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.8,
      "reason": "Results are explicitly normalized to and compared against ICNIRP basic restrictions."
    },
    {
      "slug": "occupational-exposure",
      "weight": 0.2,
      "reason": "Involves device-related EMF exposure assessment, though not explicitly occupational."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1109/iembs.2006.260022
PubMed: 17945897

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