Recent Progress on Nanomaterials for NO2 Surface Acoustic Wave Sensors

Abstract

NO2 gas surface acoustic wave (SAW)sensors are under continuous development due to their high sensitivity, reliability, low cost and room temperature operation. Their integration ability with different receptor nanomaterials assures a boost in the performance of the sensors. Among the most exploited nano-materials for sensitive detection of NO2 gas molecules are carbon-based nanomaterials, metal oxide semiconductors, quantum dots, and conducting polymers. All these nanomaterials aim to create pores for NO2 gas adsorption or to enlarge the specific surface area with ultra-small nanoparticles that increase the active sites where NO2 gas molecules can diffuse. This review provides a general overview of NO2 gas SAW sensors, with a focus on the different sensors’ configurations and their fabrication technology, on the nanomaterials used as sensitive NO2 layers and on the test methods for gas detection. The synthesis methods of sensing nanomaterials, their functionalization techniques, the mechanism of interaction between NO2 molecules and the sensing nanomaterials are presented and discussed.

Recent Advances in Fiber-Optic Sensors for the Detection of Inorganic Acidic Gases

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Carbon Nanofibers Synthesized at Different Pressures for Detection of NO2 at Room Temperature

“…The drawbacks of traditional semiconductor-based gas sensors can be solved by the application of nanomaterials as active layers for the sensors making it possible to operate at room temperature [11]. Surface acoustic wave sensors are also used for NO 2 detection [12,13], but the chemiresistive sensors are considerably cheaper.…”

Chemresistive Detection of NO2 of ppb Level in Humid Air at 350 K Using Azo-Spaced Polycroconamide

“…Over the past few decades, extensive research has been conducted on NO 2 gas sensors. Various monitoring techniques have been developed, including electrochemical, optical, , surface acoustic wave, , calorimetric, microelectromechanical system, , and chemresistive , methods. While each sensing technology has its own advantages and disadvantages, cost and portability are two major factors to consider when using gas sensors in practical applications.…”