A high-performance fluorescence BTEX sensor: film device optimization and optical unit design

BTEX (benzene, toluene, ethylbenzene, and xylenes) are highly volatile and carcinogenic, making their on-site and real-time monitoring critical. Existing techniques, however, are hard to simultaneously achieve ppb-level sensitivity, rapid response, and long-term stability. To address this challenge, we developed a high-performance film-based fluorescence sensor using a highly fluorescent perylene bisimide derivative (P-PBI) as the sensing material. Through P-PBI-based film device optimization and improved optical unit design, our sensor achieves a significantly enhanced signal-to-noise ratio (SNR), enabling ultrahigh sensitivity (benzene: 8.6 ppb; toluene: 2.3 ppb; ethylbenzene: 1.9 ppb; o-xylene: 1.2 ppb; m-xylene: 2.0 ppb; p-xylene: 1.3 ppb), fast response (<4 s), and rapid recovery (<10 s). In addition, our sensor also demonstrates exceptional robustness, maintaining stability over eight months and enduring 1,000 fatigue cycles tests—outperforming flame ionization detectors (FID) generally coupled with gas chromatography (GC) and portable photoionization detectors (PID). Field tests in gas stations, adhesive workshops, and public smoking areas further validated the sensor’s reliability in real-world scenarios. This work provides a convenient solution for on-site and real-time BTEX monitoring, with significant implications for improving occupational and environmental safety.