Microwave-induced thermoelastic pressure wave propagation in the cat brain

Area of Science:

• Biophysics
• Neuroscience
• Electromagnetics

Background:

• Understanding the physical interactions between electromagnetic fields and biological tissues is crucial.
• Pulsed microwave exposure is utilized in various applications, necessitating research into its bioeffects.

Purpose of the Study:

• To directly measure acoustic pressure wave propagation in feline brains exposed to pulsed microwaves.
• To determine the acoustic wave velocity induced by microwave irradiation.

Main Methods:

• Direct application of short rectangular microwave pulses (2 microseconds, 15 kW peak power) at 2.45 GHz to the cat's occipital pole.
• Stereotactic insertion of a hydrophone transducer into the anesthetized cat's brain to detect acoustic waves.
• Utilizing a matrix of drilled holes in the skull for transducer placement.

Main Results:

• Direct measurements confirmed the induction of acoustic pressure waves in the cat brain by pulsed microwaves.
• The propagation velocity of these induced acoustic waves was measured to be 1523 m/s.

Conclusions:

• Pulsed microwave irradiation directly generates measurable acoustic pressure waves within brain tissue.
• The findings provide direct evidence of a physical mechanism linking microwave energy absorption to mechanical wave generation in the brain.