Hand-held electron spin resonance scanner for subcutaneous oximetry using OxyChip.

Area of Science:

• Biomedical Engineering
• Medical Physics
• Analytical Chemistry

Background:

• Electron spin resonance (ESR) is a technique for measuring oxygen partial pressure (pO2) in biological settings.
• Conventional ESR methods utilize large magnets, limiting their clinical applicability.
• A novel compact ESR scanner has been developed for transcutaneous pO2 measurements.

Purpose of the Study:

• To extend the capability of a compact ESR scanner for subsurface (subcutaneous) pO2 measurements.
• To validate the scanner's performance using an artificial tissue emulating (ATE) phantom.
• To assess the potential for local static magnetic field operation in ESR measurements.

Main Methods:

• A new compact ESR scanner was designed for subcutaneous measurements up to 2 mm deep.
• The scanner utilizes pulsed ESR signals from embedded 1-mm oxygen-sensing paramagnetic implants (OxyChip).
• Key components include a static magnetic field source and a compact microwave resonator.

Main Results:

• The scanner accurately measured pO2 levels (0, 7.6, 30, 160 mmHg) from an OxyChip embedded 1.5 mm deep in an ATE phantom.
• A linear relationship between 1/T2 and pO2 was observed.
• The relative reading accuracy was approximately 10%.

Conclusions:

• The compact ESR scanner successfully reported subcutaneous pO2 data externally.
• This technology is feasible for preclinical and clinical applications in subcutaneous pO2 monitoring.
• The scanner has potential for integration with artificial skin grafts for wound healing, combining therapy and diagnostics.