Wearable Antennas for Sensor Networks and IoT Applications: Evaluation of SAR and Biological Effects.

Abstract

In recent years, there has been a rapid development in the wearable industry. The growing number of wearables has led to the demand for new lightweight, flexible wearable antennas. In order to be applicable in IoT wearable devices, the antennas must meet certain electrical, mechanical, manufacturing, and safety requirements (e.g., specific absorption rate (SAR) below worldwide limits). However, the assessment of SAR does not provide information on the mechanisms of interaction between low-intensity electromagnetic fields emitted by wearable antennas and the human body. In this paper, we presented a detailed investigation of the SAR induced in erythrocyte suspensions from a fully textile wearable antenna at realistic (net input power 6.3 mW) and conservative (net input power 450 mW) conditions at 2.41 GHz, as well as results from experiments on the stability of human erythrocyte membranes at both exposure conditions. The detailed investigation showed that the 1 g average SARs were 0.5758 W/kg and 41.13 W/kg, respectively. Results from the experiments demonstrated that the short-term (20 min) irradiation of erythrocyte membranes in the reactive near-field of the wearable antenna at 6.3 mW input power had a stabilizing effect. Long-term exposure (120 min) had a destabilizing effect on the erythrocyte membrane.

AI evidence extraction

Main findings

A fully textile wearable antenna at 2.41 GHz produced 1 g average SARs of 0.5758 W/kg at 6.3 mW net input power and 41.13 W/kg at 450 mW net input power in erythrocyte suspensions. In experiments on erythrocyte membrane stability, 20 min irradiation at 6.3 mW had a stabilizing effect, while 120 min exposure had a destabilizing effect.

Outcomes measured

• 1 g average SAR in erythrocyte suspensions
• stability of human erythrocyte membranes

Limitations

• In vitro study using erythrocyte suspensions; may not generalize to whole-body or in vivo effects
• Mechanistic details of interaction are not provided in the abstract
• Sample size and statistical methods are not reported in the abstract
• Biological effects described for 6.3 mW condition; effects at 450 mW are not clearly stated in the abstract

{
    "study_type": "other",
    "exposure": {
        "band": "RF",
        "source": "wearable antenna",
        "frequency_mhz": 2410,
        "sar_wkg": null,
        "duration": "short-term (20 min) and long-term (120 min)"
    },
    "population": "human erythrocyte suspensions (in vitro)",
    "sample_size": null,
    "outcomes": [
        "1 g average SAR in erythrocyte suspensions",
        "stability of human erythrocyte membranes"
    ],
    "main_findings": "A fully textile wearable antenna at 2.41 GHz produced 1 g average SARs of 0.5758 W/kg at 6.3 mW net input power and 41.13 W/kg at 450 mW net input power in erythrocyte suspensions. In experiments on erythrocyte membrane stability, 20 min irradiation at 6.3 mW had a stabilizing effect, while 120 min exposure had a destabilizing effect.",
    "effect_direction": "mixed",
    "limitations": [
        "In vitro study using erythrocyte suspensions; may not generalize to whole-body or in vivo effects",
        "Mechanistic details of interaction are not provided in the abstract",
        "Sample size and statistical methods are not reported in the abstract",
        "Biological effects described for 6.3 mW condition; effects at 450 mW are not clearly stated in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "wearable antenna",
        "IoT",
        "sensor networks",
        "RF exposure",
        "2.41 GHz",
        "specific absorption rate",
        "SAR",
        "erythrocytes",
        "membrane stability",
        "reactive near-field",
        "textile antenna"
    ],
    "suggested_hubs": []
}

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