Sniffing Out the Foundational Science of Sensors

Estimated reading time: 9 minutes

A great sensing material is essential, but it won't work by itself. Just as a nose needs a body and brain, sensing materials need to be part of a bigger mechanism. Unfortunately, getting these materials to work together within a sensor is often a challenge.

Printing Nanoparticle Ink

"Ink" made of sensing nanoparticles printed onto paper, plastic, rubber, or fabric could allow engineers to create smaller and more flexible sensors.

"Making particles is one thing. But from those particles, making a functional ink is not trivial," said ORNL scientist Pooran Joshi, in a slight understatement.

One ORNL study tackled the best way to turn copper-based nanoparticles into high-quality inkExternal link. By shining a high-intensity light for only a few millionths of a second, scientists fused the nanoparticles together without melting the surface underneath. When the copper-based nanoparticle ink fused together, it created a printed surface. Researchers then used the printed surface as a component in a temperature sensor.

Combining Nanotubes and Nanocrystals

Scientists know that sensors made of nanotubes and nanocrystals could detect as little as one part per million of a gas – if only they can get these two materials to work together.

Ralu Divan and her team at ANL discovered a way to add nanocrystals of zinc oxide – which is already used in sensors – to carbon nanotubes. Sensors that use the two together could be far more sensitive to methane than current technology. By placing the zinc oxide nanocrystals down atom by atomExternal link, they created a thin, consistent layer on top of the nanotubes. With this process, companies can precisely control the zinc oxide's thickness and coverage.

To examine the bonds between the nanocrystals and nanotubes, the team relied on the Center for Nanoscale Materials, an Office of Science user facility at ANL. "Having everything in one place has saved a lot of time and we were able to move faster than we expected," said Divan.

As a result, they developed a sensor that could detect much lower concentrations of methane than previous ones. Operators can use it again in seconds instead of minutes or hours.

This sensor improved so much on the existing technology that in 2016, R&D 100 Magazine recognized it as an R&D 100 finalistExternal link. The research team is now working with the Array of Things project, a collaboration between the University of Chicago and ANL. As part of the effort to collect real-time data from hundreds of sensors across Chicago, the Array of Things team anticipates using these methane sensors in the future.

Projects such as the Array of Things have the potential to transform cities into networks of sensors, placing digital eyes and noses throughout the built landscape. But these networks and technologies wouldn't be possible without a solid scientific foundation. Nothing may match the human nose's versatility, but research the Office of Science is supporting helps fill in the gaps of our biological capabilities.

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