From disease-linked breath molecules to food spoilage and environmental pollutants, researchers are rethinking how sensors recognize the subtle molecular signatures hidden within complex odors. Paper: “Smelltronics” - From Gas to Smell Sensing. AI-generated abstract conceptual image created using ChatGPT/OpenAI A review recently published in the journal Advanced Materials examined recent trends in smell and odor-sensing studies, collectively referred to as “smelltronics”. The authors describe smelltronics as a materials-focused approach that bridges conventional gas sensing and biological olfaction by targeting larger, information-rich volatile organic compounds (VOCs) and designing sensing interfaces that can distinguish subtle differences in molecular structure, rather than relying primarily on downstream pattern recognition. Conceptual overview of smelltronics. The domain of chemical sensing is undergoing a transformation from traditional gas sensing, which predominantly focuses on highly volatile gases, to smelltronics, which seeks to detect and differentiate complex VOCs that convey specific odor information. To achieve precise odor identification, smelltronics relies on the development of three hierarchies: (1) diverse sensing materials engineered for specific interactions, (2) devices that transduce physicochemical events into digitized signals, and (3) systems that integrate sensor arrays with information science. Engineering Materials for Odor Recognition Noble metals, including platinum, gold, and palladium, can be incorporated into metal oxide chemiresistors to enhance their sensitivity to hydrogen, nitrogen dioxide, carbon monoxide, and other small gases. Tin dioxide nanowires have been functionalized using palladium, gold, or platinum nanoparticles and integrated into chemiresistors. Octadecylphosphonic acid (ODPA) has been used to modify zinc oxide nanowire-based chemiresistors to accelerate sensor recovery during nonanal gas sensing. Results showed that the ODPA-modified zinc oxide chemiresistor detected nonanal with higher sensitivity than the unmodified chemiresistor and did so reversibly. Cysteine was used to functionalize gold nanorods or nanoparticles, which were then used as plasmonic aggregative colorants. Gold nanoparticles with cysteine display color changes when exposed