Vanadium oxide materials create promising new optic sensors

A prototype sensor system compact enough to be fitted to a drone and with potential in precision agriculture and elsewhere has been developed by an international team.

According to a statement from RMIT University – whose researchers collaborated with those from City University of New York (CUNY), the University of Melbourne and the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS) – the “flat-optics technology” could improve on traditional optical lenses in various industries.

The result can “rapidly switch between edge detection – imaging the outline of an object, such as a fruit – and extracting detailed infrared information” without creating and needing to process large data volumes.

“The capability to switch to a detailed infrared image is a new development in the field” according to RMIT and could result in pinpointing where pest control, fertilisation or water was required at a plant level.

The results are published in Nature Communications (accessible at the link.)

Lead author Dr Michele Cotrufo said the ability to switch was significant.

“While a few recent demonstrations have achieved analogue edge detection using metasurfaces, most of the devices demonstrated so far are static. Their functionality is fixed in time and cannot be dynamically altered or controlled,” said Corufo, who conducted his research at CUNY.

“Yet, the ability to dynamically reconfigure processing operations is key for metasurfaces to be able to compete with digital image processing systems. This is what we have developed.”

TMOS Chief Investigator Professor Madhu Bhaskaran (pictured on left) and her team at RMIT engineered the sensor system out of a filter made of vanadium dioxide and able to switch between edge detection and detailed infrared imaging.

“Materials such as vanadium dioxide add a fantastic tuning capability to render devices ‘smart’”, said Bhaskaran.

“When the temperature of the filter is changed, the vanadium dioxide transforms from an insulating state to a 

metallic one, which is how the processed image shifts from a filtered outline to an unfiltered infrared image.”

“These materials could go a long way in futuristic flat-optics devices that can replace technologies with traditional lenses for environmental sensing applications – making them ideal for use in drones and satellites, which require low size, weight and power capacity.

According to the statement RMIT holds a granted US patent and has a pending Australian patent application for the method of producing vanadium dioxide films.

PhD scholar Shaban Sulejman from the University of Melbourne, who is a co-author on the paper, said the design and materials in the filter were amenable to mass-production.

“It also operates at temperatures compatible with standard manufacturing techniques, making it well-placed to integrate with commercially available systems and therefore move from research to real-world usage rapidly,” added Sulejman.