We report a waveguide-based optical sensor which enables multi-analyte detection of gases (methane, acetylene, acetone and ethanol) in the mid-infrared spectral region. Selectivity and sensitivity of detection was enabled by chemical functionalization of an amorphous silicon (a-Si) ridge waveguide with multilayers of ZnO and SiO<sub>2</sub> nanoparticles with diameters of 4.2 nm and 20 nm, respectively. The a-Si waveguide was prepared by complementary metal–oxide–semiconductor (CMOS) processes capable of wafer-scale device production. The nanoparticles were strategically assembled within the coatings using the layer-by-layer (LbL) technique, which enables the deposition of conformal coatings of controlled nanoscale thickness and composition. The effect of varying size and surface charge of the nanoparticles on the thickness and morphology of the assembled films has been investigated. The assembled nanosized particles have provided a large surface area for gas adsorption and concentrated gas molecules within the evanescent field of the optical sensor, thus dramatically enhancing sensitivity of gas detection. Importantly, sensitivity of gas detection could be also enhanced by the deposition of a larger number of nanoparticle layers within LbL films.  At the same time, selectivity of the detection was achieved through a combination of wavelength-specific sensing and preferential adsorption of gas molecules on specific type of nanoparticles (such as stronger adsorption of acetone vs. methane on ZnO nanoparticles).  Selective and reversible sensing of methane, acetylene, acetone and ethanol using the nanoparticle-enabled waveguide-based platform has been demonstrated in the mid-infrared region.<br/>

Nanoparticle-enabled, waveguide-based, mid-infrared sensor for selective detection of gases

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.