Functional mechanisms of polymer-based in vivo reference electrodes.

Area of Science:

• Biomaterials Science
• Electrochemistry
• Medical Device Engineering

Background:

• Reference electrode catheters are essential for accurate electrochemical measurements in biological systems.
• Haemocompatibility and stability in physiological fluids are critical challenges for implantable or in-vivo devices.
• Poly(2-hydroxyethyl methacrylate) (pHEMA) is a biocompatible polymer with potential for use in liquid junction interfaces.

Purpose of the Study:

• To develop and characterize a novel reference electrode catheter utilizing a porous pHEMA liquid junction.
• To investigate the ion transport properties and stability of the pHEMA-based reference electrode in various physiological environments.
• To elucidate the mechanisms underlying the stability and performance of the pHEMA reference electrode.

Main Methods:

• Fabrication of a reference electrode catheter incorporating a porous pHEMA liquid junction.
• Evaluation of ion transport through pHEMA membranes in electrolyte solutions, plasma, and whole blood.
• Assessment of the electrochemical stability of the reference electrode over an 8-hour period.

Main Results:

• The pHEMA-based reference electrode catheter demonstrated rapid attainment of a steady state in diffusion properties.
• Plasma enhanced ion transport by approximately 10%, while whole blood decreased transport rates by 40%.
• The catheter maintained stability within 1 mV over an 8-hour period.

Conclusions:

• The pHEMA-based reference electrode catheter offers a stable and haemocompatible solution for in-vivo electrochemical measurements.
• Material properties of pHEMA, including controlled diffusion and limited protein adsorption, contribute to its stability.
• The polymer's response to pH and micromechanical fluctuations may facilitate interface renewal, enhancing long-term performance.