Abstract
This work presents a comprehensive review on gas sensors based on localized surface plasmon resonance (LSPR) phenomenon, including the theory of LSPR, the synthesis of nanoparticle-embedded oxide thin films, and strategies to enhance the sensitivity of these optical sensors, supported by simulations of the electromagnetic properties. The LSPR phenomenon is known to be responsible for the unique colour effects observed in the ancient Roman Lycurgus Cup and at the windows of the medieval cathedrals. In both cases, the optical effects result from the interaction of the visible light (scattering and absorption) with the conduction band electrons of noble metal nanoparticles (gold, silver, and gold–silver alloys). These nanoparticles are dispersed in a dielectric matrix with a relatively high refractive index in order to push the resonance to the visible spectral range. At the same time, they have to be located at the surface to make LSPR sensitive to changes in the local dielectric environment, the property that is very attractive for sensing applications. Hence, an overview of gas sensors is presented, including electronic-nose systems, followed by a description of the surface plasmons that arise in noble metal thin films and nanoparticles. Afterwards, metal oxides are explored as robust and sensitive materials to host nanoparticles, followed by preparation methods of nanocomposite plasmonic thin films with sustainable techniques. Finally, several optical properties simulation methods are described, and the optical LSPR sensitivity of gold nanoparticles with different shapes, sensing volumes, and surroundings is calculated using the discrete dipole approximation method.
Highlights
To partially expose the nanoparticles embedded in the metal oxide thin film, a lowTo partially expose the nanoparticles embedded in the metal oxide thin film, a pressure capacitively coupled plasma (CCP) treatment is a meaningful alternative to chemlow‐pressure capacitively coupled plasma (CCP) treatment is a meaningful alternative to ical etching
A review is presented on gas sensors based on the localized surface plasmon resonance (LSPR) phenomenon, focused on earliest and modern applications of plasmonic nanoparticles
Among several applications that plasmonic nanoparticles can offer, LSPR sensing platforms have been the focus of much research due to the straightforward detection mechanism and experimental setups needed
Summary
The human olfactory system (Figure 1) is used to evaluate the quality of food, drinks, perfumes, cosmetics, and chemical products. The sensation, perception, and detection limit depend upon each person’s anatomy, experience, and memory For these reasons, and in order to find reliable alternatives to the nonportable gas chromatography and mass spectrometry analytical techniques, portable gas sensors, known as electronic-nose (e-nose) systems, have been the focus of several research projects [1]. It consists of (i) a system to feed the gas (to mimic the nose), (ii) a sensor array (to mimic primary neurons in the cribriform plate), (iii) data preprocessing (to mimic secondary neurons), and (iv) the analysis and pattern recognition system
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