Electric current generated by ultrasonically induced Lorentz force in biological media

Area of Science:

• Biophysics
• Medical Instrumentation
• Acoustic Physics

Background:

• Electrical conductivity is a key parameter in biological tissues.
• Measuring conductivity non-invasively is challenging.
• Ultrasound and magnetic fields can induce measurable currents in conductive media.

Purpose of the Study:

• To develop and validate a method for determining electrical conductivity using ultrasound and magnetic fields.
• To assess the proportionality between induced current and medium conductivity.
• To explore the potential for non-invasive conductivity measurements in biological samples.

Main Methods:

• Applied a 0.35 T magnetic field and 500 kHz pulsed ultrasound to solutions.
• Measured induced electric current density using specialized electrodes.
• Validated the method with saline solutions of known conductivity.
• Tested the technique on a porcine blood sample, varying hematocrit.

Main Results:

• The induced electric current was directly proportional to the medium's electrical conductivity.
• Measured current magnitude was 50 nA for a 0.5 S/m saline solution.
• Electrode placement confirmed only a fraction of the total current was measured.
• Successfully determined blood conductivity as a function of hematocrit.

Conclusions:

• The ultrasound-induced current method shows potential for accurate electrical conductivity determination.
• This technique offers a non-invasive approach for biological media analysis.
• Further development could lead to new diagnostic tools for assessing tissue properties.