Multiple VOCs sensing by monitoring the molecular diffusion through holographic thin gratings

The detection of volatile organic compounds (VOCs) using transmission holographic gratings is a well-explored area of research. In this study we use a high-resolution, one dimensional, nanometric phase grating operating in a mixed Bragg/Raman-Nath regime to detect low concentrations of various volatile compounds in air. By leveraging the high sensitivity of the grating structure and analyzing the time-dependent response of its diffraction efficiency, we are able to distinguish between different VOCs at concentrations as low as 1ppm. In particular, this is achieved through analysis of the transient response, which correlates with the diffusion time constant of gas molecules within the polymer matrix. The experimental results and data analysis demonstrate the potential of this approach for the development of compact, low-cost VOC sensors.