How to detect carbon monoxide with nanowires and micro-hotplates Wednesday, 01 June 2016

Carbon monoxide is a poisonous gas and an environmental pollutant, but has no odour, taste, or colour, making it difficult to detect. Now Japanese scientists have found an innovative method to build sensors that can determine carbon monoxide concentrations.

The scientists from the Okinawa Institute of Science and Technology Graduate University (OIST) worked with researchers from the University of Toulouse on the project. The basis of the carbon monoxide detector? Copper oxide nanowires, approximately 1000 times thinner than the average human hair.

These nanowires chemically react with carbon monoxide, creating an electrical signal that can then be used to quantify the concentration of carbon monoxide.

But the researchers faced issues which hampered the use of nanowires: how would they (or the industry) be able to integrate nanowires into devices that are big enough to be handled, and can also be easily mass produced? And secondly, how would manufacturers control the number and position of nanowires in such devices?

Dr Steinhauer, a postdoctoral scholar at OIST, worked with Prof Sowwan and researchers from the University of Toulouse to resolve these issues.

“To create copper oxide nanowires, you need to heat neighbouring copper microstructures,” explained Dr Steinhauer.

“Starting from the microstructures, the nanowires grow and bridge the gap between the microstructures, forming an electrical connection between them.”

Key to the development was the micro-hotplate developed by the University of Toulouse, a thin membrane that can heat up to several hundred degrees Celsius, but with very low power consumption.

Integrating the copper microstructures onto the micro-hotplate, researchers were able to exert a high degree of control over the quantity and position of the nanowires. The micro-hotplate also provided the scientists with data on the electrical signal that goes through the nanowires.

The final result is an extremely sensitive sensor which integrates copper oxide nanowires with micro-hotplates, capable of detecting very low concentrations of carbon monoxide.

According to Prof Sowwan, this is the first step towards next generation gas sensors, and the approach is both cost-effective and suitable for mass production.

The breakthrough could also help scientists come to a better understanding of why the performance of sensors decrease over the span of their lifetime.

By growing the nanowires in a controlled atmosphere, the researchers will be able to start performing gas sensing measurements from the very beginning, allowing them to capture data on the sensor's performance from the very beginning.

Don't forget to register for the Australian Engineering Conference 2016 in Brisbane on November 23-25.