Nanomaterial coating improves chemical sensor selectivity

Chemical vapor sensors are used in agriculture, disease diagnosis, and many other applications. They must be both sensitive — able to detect very low concentrations of substances — and selective — able to distinguish different substances from each other.

Sensors based on two-dimensional transition metal dichalcogenides (TMDCs) have achieved record levels of sensitivity toward certain vapors. However, these devices lack sufficient selectivity, which limits their application. Motala et al. developed a device that could help overcome the selectivity hurdle of 2D TMDC-based vapor sensors.

The authors used vacuum technology to coat an optical fiber with thin-film crystalline molybdenum disulfide (MoS₂), a TMDC. They exposed this coated optical fiber to 12 organic vapors. The unique properties of the coating allowed them to observe optical changes of the fiber that corresponded to different vapors.

“Our findings represent a noteworthy advance in the integration of 2D materials into sensor constructs using vacuum deposition technologies,” said author Nicholas Glavin. “In general, this approach represents a step towards highly sensitive, selective, and completely reusable gas sensors based upon 2D nanomaterials that is cost effective and scalable.”

The researchers discuss several mechanisms underlying the selectivity of the MoS₂-coated optical fiber sensor including enhanced receptivity to electron donor/acceptor vapor species, aromatic compounds, substances with high refractive index, and chemical intercalants.

Next, the authors will package this sensor in a more compact platform and continue testing its capabilities.

“Another very exciting thing about this finding is that we have a suite of such TMDC materials,” said author Deep Jariwala. “This means there is a whole range of fiber-based sensors we can investigate for a range of applications.”

Source: “Selective vapor sensors with thin-film MoS₂ coated optical fibers,” by Michael Motala, Lucas K. Beagle, Jason Lynch, David Moore, Peter Stevenson, Anna Benton, Ly D. Tran, Luke Baldwin, Drake Austin, Christopher Muratore, Deep Jariwala, and Nicholas R. Glavin, JVST: A (2022). The article can be accessed at https://aip.scitation.org/doi/full/10.1116/6.0001759 .

This paper is part of the Celebrating the Early Career Professionals Contributing to the Advancement of Thin Films, Surfaces, Interfaces, and Plasmas Collection, learn more here .