Measurements of Polycyclic Aromatic Hydrocarbon Vapors Using a Nanomechanical Sensor

The detection of hazardous polycyclic aromatic hydrocarbon (PAH) vapors is critical yet challenging due to their extremely low vapor pressures, which impede in-situ monitoring. To overcome measurement limitations, a Membrane-type Surface stress Sensor (MSS), which is highly sensitive to semi-volatile organic compounds (SVOCs) at low concentrations, was coated with polycaprolactone (PCL) and utilized for the sensitive detection of PAH vapors. Anthracene and fluoranthene were successfully detected at room temperature with concentrations ranging from 2% to 8% of their respective saturated vapor pressures. Time-series measurements revealed consistent exponential absorption-desorption kinetics for both compounds. The system achieved estimated limits of detection of 160 ppt for anthracene and 150 ppt for fluoranthene, based on dilution ratios and literature vapor pressures. Notably, both compounds exhibited comparable responses relative to absolute vapor concentration, suggesting a consistent absorption mechanism despite differing vapor pressures. The results highlight the potential of PCL-coated MSS as a compact, room-temperature platform for sub-parts-per-billion (ppb) PAH vapor detection.