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Researchers from the City University of New York (CUNY), the University of Melbourne, the Royal Melbourne Institute of Technology (RMIT), and the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS) are pioneering a revolutionary metasurface sensor that can dynamically switch from edge detection to infrared in real-time, promising to increase productivity and reduce costs for farmers–with the study published on Nature Communications.
Utilization of the lightweight sensor can increase productivity and reduce costs for farmers, as the technology will have the capability to accurately identify which crops need irrigation, fertilization, and pest control, moving away from a one-size-fits-all method of crop management.
How the Sensor Works
The material used for the sensor has a thin layer of vanadium dioxide (VO2) embedded within a thicker silicon metasurface filter. The reconfiguration of the device’s function happens when the material gets heated up to a determined threshold and the VO2 goes into its insulator-to-metal phase.
“Phase change materials such as vanadium dioxide add a fantastic tuning capability to render devices ‘smart,'” said Madhu Bhaskaran, TMOS Chief Investigator and a professor at RMIT. “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.”
Co-author Michele Cotrufo also said, “While a few recent demonstrations have achieved analog 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. Yet, the ability to dynamically reconfigure processing operations is key for metasurfaces to be able to compete with digital image processing systems.”
Innovations and Future Directions
Other than its reconfigurability, the metasurface was able to match the expected performance in comparison to other static counterparts in terms of its numerical aperture of about 0.26, efficiency, full isotropy, and polarization independence.
Researcher Shaban Sulejman also mentioned that it functions at temperatures that align with standard manufacturing methods. It makes it ideal for seamless integration with commercially available systems and enables a swift transition from research to real-world applications.
Reconfigurable image processing metasurfaces have the potential to be developed into devices that can perform a range of tasks in a temperature-controlled environment, including bandpass filtering, image convolution, detecting direction, imaging polarization, and quantitative phase microscopy.
“Traditional optical elements have long been the bottleneck preventing the further miniaturization of devices,” said Ann Roberts, chief investigator at TMOS, highlighting the potential transformative impact that flat optics can have on numerous industries. “The ability to replace or complement traditional optical elements with thin-film optics breaks through that bottleneck.”
RMIT University possesses a US patent and is awaiting approval for an Australian patent application concerning its proprietary method of producing vanadium dioxide films, potentially applicable across a diverse array of uses.
The researchers suggest the technology can be further expanded to explore non-volatile phase change materials and optically induced heating. TMOS Partner Investigator Andrea Alu says, “Integrate it with an external pump laser for optically-induced heating. The latter scenario may open interesting avenues for all-optically reconfigurable nonlinear analog computation.”
