Magnetic induction spectroscopy (MIS)-probe design for cervical tissue measurements

Area of Science:

• Biomedical Engineering
• Electromagnetism
• Medical Imaging

Background:

• Magnetic induction spectroscopy (MIS) is crucial for bio-impedance measurements, benefiting from gradiometer sensitivity.
• Traditional gradiometers offer high interference immunity but can have broad sensitivity.
• Developing advanced gradiometers is key for precise in vivo tissue analysis.

Purpose of the Study:

• To develop and evaluate a novel ferrite-cored coaxial gradiometer probe for in vivo bio-impedance measurements.
• To compare the performance of the ferrite-cored probe against an air-cored probe.
• To assess the probe's accuracy in measuring the impedance spectra of cervical tissues.

Main Methods:

• A 29 mm diameter ferrite-cored coaxial gradiometer probe with ferrite screening was designed.
• Magnetic screening efficiency was compared between the ferrite-cored and air-cored probes.
• Signal sensitivity and conductivity measurements were performed using saline samples and simulated using finite element methods.

Main Results:

• The ferrite-cored probe demonstrated confined sensitivity, unlike the air-cored probe with wide sensitivity.
• Measurement accuracy for the air-cored probe improved from 0.09 S m⁻¹ to 0.05 S m⁻¹ with increasing frequency.
• The ferrite-cored probe showed improved accuracy from 0.28 S m⁻¹ to 0.04 S m⁻¹ across tested frequencies.

Conclusions:

• The ferrite-cored gradiometer probe provides localized sensitivity crucial for accurate bio-impedance measurements.
• In vivo human hand measurements confirmed the probe's ability to yield conductivity data consistent with established values.
• The developed probe shows promise for advanced in vivo tissue impedance spectroscopy.