Temperature coefficient of and oxygen effect on the antimony microelectrode

Area of Science:

• Biomedical Engineering
• Electrochemistry
• Physiology

Background:

• Accurate in vivo pH measurement of biological fluids is crucial for physiological monitoring.
• Metal-metal oxide microelectrodes offer potential for minimally invasive pH sensing.
• Antimony (Sb) microelectrodes are candidates for such applications, but their performance characteristics require thorough evaluation.

Purpose of the Study:

• To investigate the effects of temperature and oxygen partial pressure on antimony (Sb) microelectrodes.
• To compare the performance of Sb microelectrodes with traditional glass pH electrodes in biological fluids.
• To estimate bullfrog blood pH using Sb microelectrodes under controlled conditions.

Main Methods:

• Examined the temperature coefficient (dE/dt) of electromotive force (EMF) for Sb microelectrodes and glass electrodes in Ringer and Tris buffer solutions.
• Developed an empirical formula to predict the change in the Sb-microelectrode slope constant with temperature.
• Assessed the influence of oxygen partial pressure (Po2) on Sb-microelectrode EMF.
• Measured bullfrog blood pH using both Sb and glass microelectrodes.

Main Results:

• Sb microelectrodes exhibited a significant temperature coefficient (-1.18 mV/°C) in Ringer solution, differing from glass electrodes (-0.43 mV/°C).
• Empirical equations were derived to predict Sb-microelectrode slope changes and pH reading deviations based on temperature.
• Sb-microelectrode EMF increased linearly with oxygen partial pressure (11.7 mV/log(Po2)).
• Bullfrog blood pH estimations were comparable between Sb microelectrodes (7.729 ± 0.111) and glass electrodes (7.697 ± 0.092).

Conclusions:

• Antimony microelectrodes demonstrate temperature-dependent behavior and sensitivity to oxygen partial pressure.
• Despite these factors, Sb microelectrodes provide reliable in vivo pH estimations in bullfrog blood, comparable to glass electrodes.
• The established empirical relationships can aid in correcting for temperature-induced variations in Sb microelectrode measurements.