Portable and Digital MOX Sensor Electronic Nose with Thermal Modulation: Design, Stability Analysis, and Long-Term...

Area of Science:

• Analytical Chemistry
• Sensor Technology
• Materials Science

Background:

• Traditional electronic noses often use fixed-temperature sensors, limiting their ability to capture complex odor profiles.
• Metal oxide (MOX) gas sensors offer sensitivity but require optimization for stability and repeatability.

Purpose of the Study:

• To develop and validate a portable electronic nose system utilizing digital MOX sensors with programmable temperature modulation.
• To assess the long-term stability, repeatability, and pattern-recognition capabilities of the developed electronic nose.
• To demonstrate the system's effectiveness in discriminating between different types of oils.

Main Methods:

• Integration of four digital MOX sensors with programmable temperature modulation for generating temperature-dependent odor fingerprints.
• Assessment of sensor performance including stability, repeatability (using Root Mean Squared Error - RMSE), and pattern recognition.
• Application of Principal Component Analysis (PCA) for signal processing and k-Nearest Neighbors (KNNs) and Multilayer Perceptrons (MLPs) for classification.
• Proof-of-concept study involving the discrimination of Extra Virgin Olive Oil and pomace oil.

Main Results:

• The electronic nose demonstrated stable responses over one month of measurements, indicating high repeatability.
• Temperature-modulated signals, processed by PCA and classified using KNNs/MLPs, achieved 100% accuracy in oil discrimination after selecting the most repeatable sensor.
• The system proved robust and capable of complex odor analysis, outperforming conventional fixed-temperature operation.

Conclusions:

• Temperature-modulated digital MOX sensors offer significant analytical potential and robustness for electronic nose applications.
• A compact, highly reproducible electronic nose platform suitable for complex odor analysis in real-world scenarios has been successfully demonstrated.
• The developed system shows promise for quality control and authentication in food and other industries.