Low-Cost Optical pH Sensor with a Polyaniline (PANI)-Sensitive Layer Based on Commercial Off-the-Shelf (COTS)...

Area of Science:

• Materials Science
• Analytical Chemistry
• Sensor Technology

Background:

• Polyaniline (PANI) is a conductive polymer with potential for chemical sensing.
• Existing PANI-based pH sensors often rely on complex and expensive excitation or detection methods.
• There is a need for cost-effective, simple, and robust pH sensing solutions.

Purpose of the Study:

• To present a novel, low-cost, and compact prototype pH sensor.
• To demonstrate a simple and efficient PANI deposition technique.
• To validate the sensor's performance across a wide pH range.

Main Methods:

• Fabrication of a PANI thin film via a low-cost liquid-phase deposition process.
• Integration of a red-light-emitting diode (LED) and photodiode (PD) for optical detection.
• Development of integrated packaging using commercial off-the-shelf (COTS) components and surface mounting technology (SMT).

Main Results:

• The PANI layer exhibited excellent stability, solvent resistance, and compatibility.
• The sensor demonstrated sensitivity in the broad pH range of 3 to 9.
• The device requires a minimal sample volume of 55 µL and uses simple optical components.

Conclusions:

• A fully functional, low-cost pH sensor prototype was successfully developed.
• The sensor's design avoids sophisticated and expensive techniques, enhancing its practicality.
• The developed sensor is suitable for numerous applications requiring reliable pH monitoring.