Nanoengineering Approaches Toward Artificial Nose

Abstract

Significant scientific efforts have been made to mimic and potentially supersede the mammalian nose using artificial noses based on arrays of individual cross-sensitive gas sensors over the past couple decades. To this end, thousands of research articles have been published regarding the design of gas sensor arrays to function as artificial noses. Nanoengineered materials possessing high surface area for enhanced reaction kinetics and uniquely tunable optical, electronic, and optoelectronic properties have been extensively used as gas sensing materials in single gas sensors and sensor arrays. Therefore, nanoengineered materials address some of the shortcomings in sensitivity and selectivity inherent in microscale and macroscale materials for chemical sensors. In this article, the fundamental gas sensing mechanisms are briefly reviewed for each material class and sensing modality (electrical, optical, optoelectronic), followed by a survey and review of the various strategies for engineering or functionalizing these nanomaterials to improve their gas sensing selectivity, sensitivity and other measures of gas sensing performance. Specifically, one major focus of this review is on nanoscale materials and nanoengineering approaches for semiconducting metal oxides, transition metal dichalcogenides, carbonaceous nanomaterials, conducting polymers, and others as used in single gas sensors or sensor arrays for electrical sensing modality. Additionally, this review discusses the various nano-enabled techniques and materials of optical gas detection modality, including photonic crystals, surface plasmonic sensing, and nanoscale waveguides. Strategies for improving or tuning the sensitivity and selectivity of materials toward different gases are given priority due to the importance of having cross-sensitivity and selectivity toward various analytes in designing an effective artificial nose. Furthermore, optoelectrical sensing, which has to date not served as a common sensing modality, is also reviewed to highlight potential research directions. We close with some perspective on the future development of artificial noses which utilize optical and electrical sensing modalities, with additional focus on the less researched optoelectronic sensing modality.

Sensors for Volatile Organic Compounds

“…For instance, the human nose can discriminate more than one trillion different olfactory stimuli . Since humans have only 400 intact olfactory receptors, it is impossible to attribute this ability to the “lock and key” model, in which each receptor responds to only one odorant . Accordingly, natural olfactory systems interpret VOCs and aromas through a relatively limited number of odorant receptors with different ligand binding affinities, followed by computational processes inside the brain.…”

“…Artificial noses have adopted a variety of sensing arrays . Nanoengineering and nanohybridization have proved successful in designing the wide variety of materials required for the array.…”

Biomaterials Technology for AgroFood Resilience

“…[400] Over the past decades, significant scientific efforts have been made to mimic the mammalian nose (electronic nose as a gas sensor) and tongue (electronic tongue as a chemical sensor) using individual cross-sensitive sensors and computational interpreters. [401,402] Researchers have applied these techniques to a wide range of food including beverages, fruits, vegetables, cooking oils, meats, and fish. [402] Recent advances in nanoengineering [401] and artificial intelligence (AI) [403] have contributed to improving these humanmimicking sensing systems.…”

“…[401,402] Researchers have applied these techniques to a wide range of food including beverages, fruits, vegetables, cooking oils, meats, and fish. [402] Recent advances in nanoengineering [401] and artificial intelligence (AI) [403] have contributed to improving these humanmimicking sensing systems. Nanoengineered materials have also been extensively used as sensing components due to their high surface area and uniquely tunable optical, electronic, and optoelectronic properties.…”

One-Dimensional Metal Oxide Nanostructures for Chemical Sensors

“…The microheater is embedded within the membrane and insulated from the interdigitated electrodes patterned on top of the membrane. The use of silicon and MEMS technologies allows for the incorporation of integrated circuits along with the driving and signal conditioning circuitry or other smart features (e.g., wireless communication) to build electronic noses with potentially low-cost production [152,153]. However, recently other substrate materials (e.g., polymers) and technologies (e.g., printing) are being explored and optimized to provide also integrated elements driven by the use of optimized active 1D MOS nanostructures that can operate at room temperature or close to it [13,154].…”