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Laser writing may enable ‘electronic nose’ for multi-gas sensor

Laser writing could enable 'electronic nose' for multi-gas sensor

Alexander Castonguay (left), graduate student in assistant professor Lauren Zarzar’s lab, and assistant professor Huanyu “Larry” Cheng used this laser setup for their multidisciplinary collaboration. Credit: Kelby Hochreither/Penn State.

Thanks to a partnership with Penn State, environmental sensors are one step closer to simultaneously sniffing multiple gases that could indicate disease or pollution. Huanyu “Larry” Cheng, assistant professor of engineering and mechanics in the College of Engineering, and Lauren Zarzar, assistant professor of chemistry at Eberly College of Science, and their teams combined laser writing and responsive sensor technologies to fabricate the first highly customizable microscale gas detection devices.

They published their technique this month in ACS Applied Materials & Interfaces

“The detection of gases is critical for several areas, including pollution monitoring, public safety and personal health care,” Cheng said. “To meet these needs, sensor equipment must be small, lightweight, inexpensive, easy to use and applicable to a variety of environments and substrates, such as clothing or pipes.”

According to Cheng, the challenge is to create devices with the desired properties that can still be customized with the infrastructure needed for accurate and accurate detection of several target gases simultaneously. That’s where Zarzar’s expertise with laser writing comes in.

“Laser writing techniques give design freedom for a wide variety of fields,” Zarzar said. “By expanding our understanding of how to directly synthesize, shape, and integrate new materials — particularly nanomaterials and nanomaterial composites — into complex systems, we can create increasingly sophisticated and useful sensing technologies.”

Her research group developed the laser-induced thermal voxel process, which enables the simultaneous creation and integration of metal oxides directly into sensor platforms. Metal oxides are materials that react with various compounds, activating the detection mechanism. Using laser writing, the researchers dissolve metal salts in water and then direct the laser into the solution. The high temperature decomposes the solution, leaving metal oxide nanoparticles that can be sintered on the sensor platform.

Laser writing could enable 'electronic nose' for multi-gas sensor

Penn State researchers used a new laser writing technique to develop the first highly customizable microscale gas detection devices. Credit: Kelby Hochreither/Penn State

The process streamlines previous methods, which required a predefined mask of the planned pattern. Any changes or adjustments required a new mask to be made, which cost time and money. Laser writing is “maskless”, according to Zarzar, and when combined with the thermal voxel process, it allows rapid iteration and testing of multiple designs or materials to find the most effective combinations.

“Precise patterning is also a necessary part of creating ‘electronic noses,’ or arrays of sensors that act like a nose and can precisely detect multiple gases simultaneously,” said Alexander Castonguay, a chemistry graduate student and co-first author on the paper. “Such accurate detection requires patterning different materials close together, at the thinnest microscale. Few patterning techniques have the resolution to do this, but the approach described in this study does. techniques and materials described here to make electronic nose prototypes.”

The researchers tested five different metals and metal combinations currently used in sensors. According to Castonguay, the point where different metal oxides meet, called a heterojunction, cultivates a unique environment at the interface of the two materials that enhances the response of gas sensors. The team found that a heterojunction of copper oxide and zinc oxide has a five to 20 times improved response to the gases tested — ethanol, acetone, nitrogen dioxide, ammonia and hydrogen sulfide — than copper oxide alone.

“This finding supports other reports in the scientific literature that creating mixed oxide systems can lead to a significant increase in sensor response and demonstrates the efficacy of the laser-induced thermal voxel technique for the fabrication of mixed oxide gas sensors,” said Castonguay. “We hope that by combining the laser writing knowledge of the Zarzar group with the wearable sensor expertise of the Cheng group, we can expand our capabilities to create new, customizable sensors.”

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More information:
Alexander C. Castonguay et al, Direct laser writing of microscale metal oxide gas sensors from liquid precursors, ACS Applied Materials & Interfaces (2022). DOI: 10.1021/acsami.2c03561

Provided by Pennsylvania State University

Quote: Laser writing could enable ‘electronic nose’ for multi-gas sensor (2022, June 29) retrieved June 29, 2022 from https://phys.org/news/2022-06-laser-enable-electronic-nose-multi-gas. html

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