Optimized Drop-Casted Polyaniline Thin Films for High-Sensitivity Electrochemical and Optical pH Sensors

Area of Science:

• Materials Science
• Electrochemistry
• Sensor Technology

Background:

• Conducting polymers offer reversible properties crucial for chemical sensors.
• Polyaniline (PANI) is a prominent material due to its stability and ease of synthesis.
• PANI's doping/de-doping process controls its properties for sensor applications.

Purpose of the Study:

• To investigate polyaniline (PANI) thin films for electrochemical and optical pH sensing.
• To correlate PANI film deposition parameters with sensor performance.
• To understand the structure-property relationship for optimized PANI-based sensors.

Main Methods:

• PANI thin films were deposited on fluorine-doped tin oxide (FTO) substrates using the drop-casting method.
• Electrochemical and UV-VIS spectroscopy were used for characterization.
• Sensor performance was evaluated by correlating deposition parameters (volume, concentration) with pH sensitivity.

Main Results:

• Characterization confirmed similar chemical properties, oxidation states, and protonation levels across samples.
• Electrochemical pH sensitivity reached 127.3 ± 6.2 mV/pH (twice the Nernst limit) for thicker, rougher films.
• Optical pH sensitivity was 0.45 ± 0.05 1/pH for less rough films, minimizing light scattering.

Conclusions:

• PANI film thickness and surface roughness significantly impact sensor performance.
• Optimized deposition parameters are key to achieving high-sensitivity PANI-based pH sensors.
• These PANI sensors demonstrate potential for high-sensitivity pH measurement applications.