Amperometric micro pH measurements in oxygenated saliva

Area of Science:

• Electrochemistry
• Biosensors
• Analytical Chemistry

Background:

• Accurate pH measurement is crucial for biological fluid analysis.
• Existing pH sensors may require large sample volumes or oxygen removal.
• Carbon fiber microelectrodes offer potential for miniaturized electrochemical sensing.

Purpose of the Study:

• To develop and validate an amperometric micro pH sensor for salivary pH determination.
• To investigate the use of chemically oxidized carbon fiber surfaces for enhanced pH sensing.
• To assess the sensor's performance in small volumes of biological fluids, including human saliva.

Main Methods:

• Fabrication of micro pH sensors using chemically oxidized carbon fiber micro-wires.
• Electrochemical characterization utilizing the quinone/hydroquinone redox couple.
• Nernstian response analysis across a relevant pH range (2-8).
• Validation using synthetic and authentic human saliva samples, comparing with commercial glass pH electrodes.

Main Results:

• The developed micro pH sensor demonstrated a Nernstian response over the pH range of 2-8.
• Successful measurement of pH in small volumes of synthetic and human saliva without oxygen removal.
• Results from the micro pH sensor correlated well with conventional glass pH electrodes.
• Oxidation of carbon fiber surfaces effectively enhanced surface quinone group population for pH sensing.

Conclusions:

• The amperometric micro pH sensor provides a viable method for accurate salivary pH measurement.
• The sensor is suitable for analyzing small biological fluid volumes, offering a significant advantage in specific applications.
• Chemically modified carbon fiber microelectrodes represent a promising platform for developing advanced biosensors.