Study type: Medical/biological study (experimental study)

Interactions between 60-GHz millimeter waves and artificial biological membranes: dependence on radiation parameters. med./bio.

Published in: IEEE Trans Microw Theory Tech 2006; 54 (6): 2534-2542

Aim of study (acc. to author)

To analyze the possible influence of 60 GHz millimeter waves on the physical properties of phospholipid layers in artificial models of biological membranes.

Background/further details

Two principal phospholipid components of biological membranes were used: dipalmitoylphosphatidycholine (DPPC) and dioleoylphosphatidylcholine (DOPC). The role of different irradiation parameters was examined (e.g. power flux density, magnetic field strength).
In the first part of the study, the effect of millimeter waves on superficial pressure of phospholipid monolayers was investigated. In the second part, the microdomain distribution in mixed phospholipid monolayers with phase separation was studied. Microdomains reflect functional specialization of the different membrane regions and play an important role in membrane interaction processes.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 GHz
Modulation type: CW
Exposure duration: continuous for 5 h
Exposure 2: 60 GHz
Modulation type: AM
Exposure duration: continuous for 5 h
Exposure 3: 60 GHz
Modulation type: CW
Exposure duration: intermittend 1 h on - 1 h off for 7 h
Exposure 4: 60 GHz
Modulation type: CW
Exposure duration: continuous for 3 h
Exposure 5: 60 GHz
Modulation type: CW
Exposure duration: continuous for 5 h

General information

For exposures 1 - 4 dipalmitoylphosphatidylcholine (DPPC) membranes in the liquid-condensed (LC) phase with an average superficial pressure of 28.5-32 mN/m were used. In exposure 5 a biphase DPPC monolayer was studied with an initial superficial pressure of 18.2 mN/m. Under normal environmental conditions, this value corresponds to liquid condensed/liquid-expanded (LC/LE) phase separation in DPPC monolayers.

Exposure 1

Main characteristics
Frequency 60 GHz
Type
Charakteristic
Polarization
  • circular
Exposure duration continuous for 5 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 82.4 V/m maximum calculated - for 50 mW incident power
power density 0.9 mW/cm² maximum calculated - for 50 mW incident power
magnetic field strength 0.219 A/m maximum calculated - for 50 mW incident power
power density 0.009 mW/cm² maximum calculated - for 0,5 mW incident power
electric field strength 8.2 V/m maximum calculated - for 0,5 mW incident power
magnetic field strength 0.022 A/m maximum calculated - for 0,5 mW incident power

Exposure 2

Main characteristics
Frequency 60 GHz
Type
Waveform
  • rectangular
Charakteristic
Polarization
  • circular
Exposure duration continuous for 5 h
Modulation
Modulation type AM
Modulation frequency 1 kHz
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 58.3 V/m maximum calculated - -
magnetic field strength 0.155 A/m maximum calculated - -
power density 0.45 mW/cm² average over time calculated - -

Exposure 3

Main characteristics
Frequency 60 GHz
Type
Charakteristic
Polarization
  • circular
Exposure duration intermittend 1 h on - 1 h off for 7 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 0.45 mW/cm² maximum calculated - -
electric field strength 58.3 V/m maximum calculated - -
magnetic field strength 0.155 A/m maximum calculated - -

Exposure 4

Main characteristics
Frequency 60 GHz
Type
Charakteristic
Polarization
  • circular
Exposure duration continuous for 3 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 0.36 mW/cm² maximum calculated - -
electric field strength 57.6 V/m maximum calculated - -
magnetic field strength 0.153 A/m maximum calculated - -

Exposure 5

Main characteristics
Frequency 60 GHz
Type
Charakteristic
Polarization
Exposure duration continuous for 5 h
Modulation
Modulation type CW
Exposure setup
Exposure source
  • pyramidal horn antenna with an aperture of 22.2 mm x 16.7 mm and an isotropic gain of 17 dB
Parameters
Measurand Value Type Method Mass Remarks
power density 0.41 mW/cm² maximum calculated - -
magnetic field strength 0.0147 A/m maximum calculated - -
electric field strength 55.5 V/m maximum calculated - -

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

Measurements of superficial pressure of phospholipid monolayers have shown weak but reproducible variations, essentially determined by superficial power flux density incident onto the membrane. Even very low power flux density levels resulted in a marked increase of lateral pressure. All other exposure parameters did not show a signifcant influence.
The AFM analysis has evidenced that low-power millimeter wave irradiation does not induce significant transformations in the phospholipid domain organization in model membranes.
The biophysical properties of phospholipid layers of biological membranes could be partly modified by low-power millimeter wave irradiation.

Study character:

Study funded by

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