Real-Time Acetone Gas Monitoring Using Calixarene-Functionalized Guided-Mode Resonance-Based Sensors.

Portable sensors to detect volatile organic compounds (VOCs) are needed for many societal and industrial applications, such as diagnosing patient health through breath analysis or monitoring industrial environments for worker safety. Acetone, a widely used industrial solvent, is an important example that requires sensitive detection to prevent hazardous exposure over workplace safety limits. Established sensor technologies suffer from drawbacks such as high operating temperatures and power consumption, long-term drift, or high complexity. Here, we present an optical gas sensor based on a guided-mode resonance (GMR) that affords handheld operation and a simple readout. The GMR sensor features a medium quality (Q-factor) and is functionalized with a calixarene layer that exhibits a refractive index change upon exposure to acetone. The sensor achieves a limit of detection (LOD) of 80 ppm for acetone vapor at room temperature, with a response following an extended Langmuir isotherm, making it highly suitable for monitoring workplace safety, where a prolonged exposure to levels >170 ppm is considered dangerous. We also show that the sensor response is repeatable within a 4.5% standard deviation across measurements, highlighting that the technology offers a low-cost, high-performance solution for monitoring workplace acetone levels.