Millimeter-Wave Heating in In Vitro Studies: Effect of Convection in Continuous and Pulse-Modulated Regimes

2019 · Unclear · Low evidence

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UnclearLow evidencePaper 1680

Study snapshot

Publicationmanual · 2019

Study typein_vitro

Reported directionUnclear

Evidence ratingLow

Abstract

Millimeter-Wave Heating in In Vitro Studies: Effect of Convection in Continuous and Pulse-Modulated Regimes Orlacchio R, Zhadobov M, Alekseev SI, Nikolayev D, Sauleau R, Le Page Y, Le Dréan Y. Millimeter-Wave Heating in In Vitro Studies: Effect of Convection in Continuous and Pulse-Modulated Regimes. Bioelectromagnetics. Published online October 3, 2019. doi.org Abstract Shallow penetration of millimeter waves (MMW) and non-uniform illumination in in vitro experiments result in a non-uniform distribution of the specific absorption rate (SAR). These SAR gradients trigger convective currents in liquids affecting transient and steady-state temperature distributions. We analyzed the effect of convection on temperature dynamics during MMW exposure in continuous-wave (CW) and pulsed-wave (PW) amplitude- modulated regimes using micro-thermocouples. Temperature rise kinetics are characterized by the occurrence of a temperature peak that shifts to shorter times as the SAR of the MMW exposure increases and precedes initiation of convection in bulk. Furthermore, we demonstrate that the liquid volume impacts convection. Increasing the volume results in earlier triggering of convection and in a greater cooling rate after the end of the exposure. In PW regimes, convection strongly depends on the pulse duration that affects the heat pulse amplitude and cooling rate. The latter results in a change of the average temperature in PW regime. Excerpt In conclusion, our results suggest that in planning in vitro studies in the MMW band, convection is one of the parameters that has to be carefully taken into account. It may affect cellular response through indirect mechanisms, such as the local change of the concentration of oxygen or nutrients transported by the culture medium. Deeper investigation of convection mechanisms requires numerical analysis of the multi-physics problem, which constitutes one of the perspectives of a future study. onlinelibrary.wiley.com

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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 typein_vitro

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposuremmWave

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Non-uniform SAR distribution during millimeter-wave exposure can trigger convective currents in liquids, affecting transient and steady-state temperature distributions. Temperature rise kinetics showed a temperature peak that occurred earlier with increasing SAR and preceded initiation of bulk convection; liquid volume and pulse duration influenced convection onset and cooling/average temperature in pulsed regimes.

Outcomes measured

Temperature dynamics/temperature rise kinetics
Convection effects in liquids during exposure
Transient and steady-state temperature distributions
Effect of liquid volume on convection and cooling rate
Effect of pulse duration (PW amplitude-modulated) on convection and average temperature

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": "mmWave",
    "source": "in vitro exposure setup",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Temperature dynamics/temperature rise kinetics",
    "Convection effects in liquids during exposure",
    "Transient and steady-state temperature distributions",
    "Effect of liquid volume on convection and cooling rate",
    "Effect of pulse duration (PW amplitude-modulated) on convection and average temperature"
  ],
  "main_findings": "Non-uniform SAR distribution during millimeter-wave exposure can trigger convective currents in liquids, affecting transient and steady-state temperature distributions. Temperature rise kinetics showed a temperature peak that occurred earlier with increasing SAR and preceded initiation of bulk convection; liquid volume and pulse duration influenced convection onset and cooling/average temperature in pulsed regimes.",
  "effect_direction": "unclear",
  "limitations": [],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "millimeter waves",
    "MMW",
    "in vitro",
    "specific absorption rate",
    "SAR gradients",
    "convection",
    "temperature distribution",
    "continuous-wave",
    "pulsed-wave",
    "amplitude modulation",
    "micro-thermocouples",
    "heating"
  ],
  "suggested_hubs": [
    {
      "slug": "5g-policy",
      "weight": 0.2,
      "reason": "Study concerns millimeter-wave exposure conditions relevant to mmWave bands used in some 5G deployments, though it is focused on in vitro heating/convection methodology rather than policy."
    }
  ]
}

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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: 10.1002/bem.22223
PubMed: Not supplied

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