Surface acoustic wave gas sensors: Innovations in functional materials, sensing dynamics, and signal analysis

Surface Acoustic Wave gas sensors have garnered increasing attention as highly sensitive, miniaturized, and wireless compatible platforms for molecular detection. Their unique ability to convert surface perturbations into measurable acoustic shifts makes them ideal for gas sensing across diverse environments. This review synthesizes reported SAW platforms across substrates and modes Rayleigh, SH-SAW, Love links transduction pathways to material choice, and benchmarks performance for key analytes, e.g., NO2, NH3, VOCs, CO2, etc. We catalogue nanostructured oxides, polymers, carbon based films, and hybrid heterojunction coatings, highlighting attributes such as porosity, surface chemistry, and interfacial charge transfer that govern sensitivity and reversibility. We also highlight the emerging use of SAW devices to probe adsorption desorption dynamics, offering analyte specific interaction signatures beyond equilibrium, offering a new perspective into analyte specific interaction pathways. Additionally, the integration of machine learning is discussed as a transformative tool for signal decoding, environmental compensation, and adaptive calibration. We also identify key challenges, cross sensitivity, signal drift, material degradation, and deployment at the edge and review recent strategies to address them. Looking ahead, we envision the evolution of SAW platforms into intelligent, autonomous sensing systems with applications in environmental monitoring, industrial process control, and healthcare diagnostics.