A carbon dioxide air-gap microelectrode based on a neutral hydrogen ion exchanger pH microelectrode

Area of Science:

• Electrochemistry
• Chemical Sensing
• Analytical Chemistry

Background:

• Accurate measurement of carbon dioxide (pCO2) is crucial in various scientific and medical fields.
• Existing pCO2 sensors can be complex or lack the necessary sensitivity and response speed.
• Development of microscale sensors is essential for in-situ and minimally invasive measurements.

Purpose of the Study:

• To describe a novel, simple, and effective potentiometric microelectrode for pCO2 gas sensing.
• To characterize the performance of the developed microelectrode in terms of response range, linearity, and speed.
• To evaluate the long-term stability and lifetime of the microelectrode.

Main Methods:

• Fabrication of a potentiometric microelectrode based on an ion-exchanger pH electrode.
• Incorporation of a hydrophobic air gap using specialized treatments.
• Testing the microelectrode's response in a flow system with varying sodium bicarbonate concentrations.
• Characterization of response linearity, Nernstian slope, response time, and sensor lifetime.

Main Results:

• The microelectrode features a tip size of 2-5 microns and an integrated air gap.
• A linear potentiometric response was observed in the concentration range of 10(-4) to 10(-2) M.
• A Nernstian slope of 59-62 mV/decade was achieved at 25 degrees C.
• Ninety-five percent steady-state response time was approximately 20-30 seconds in a flow system.
• The sensor demonstrated a lifetime exceeding one week.

Conclusions:

• A simple and efficient potentiometric pCO2 microelectrode has been successfully developed.
• The microelectrode exhibits excellent performance characteristics, including a wide linear range, fast response, and good stability.
• This sensor technology holds promise for various applications requiring precise pCO2 monitoring.