Vortex Engineering on Oxide Bowl-Coated Oxide/Gold Dual-Layer Array for Dual Electrical/Spectroscopic Monitoring of Volatile Organic Compounds

Integrating real-time electrical gas sensing and highly identifiable surface-enhanced Raman spectroscopy (SERS) for volatile organic compounds (VOCs) monitoring holds significant potential for safeguarding public health and safety. However, this technique remains in the proof-of-concept stage because the performance and reproducibility of devices fall short of meeting the practical application requirements. This work addresses this challenge by employing vortex engineering on a bifunctional dual-layer array of Ni-doped SnO2 (Ni-SnO2) bowl-coated on Ni-SnO2/Au/SiO2 and developing highly reproducible device fabrication. In the dual-layer array, vortices generated in upper Ni-SnO2 bowls slow down the VOC flow and direct its delivery to gaps between lower Ni-SnO2/Au/SiO2 units that are critical to SERS and electrical sensing. Experimental results show that the vortex effect in the array enables a low limit of detection of 10 ppb with a response and recovery in seconds. The excellent practicality of the array has been demonstrated through a ca. 100 hours of quantitative dual-monitoring of styrene in a spacious environment (similar to 60 m(3)) with a 5-meter distance between the leakage source and the array. This work advances dual-monitoring sensors for practical applications and offers insights for designing gas-sensing materials and devices.