Duke Uni to Make Multispectral Imaging and Printing More Accessible

Multispectral imaging and printing might soon become available for daily usage, thanks to the work of a research team at Duke University. In finding a solution to significantly cut down the costs of the expensive process of color and infrared printing, they could have paved the way to revolutionize every industry reliable on multispectral images.

A World-Changing Technology

Be it the identification of minerals, the diagnosis of cancerous melanomas or the prediction of next week’s weather – without displaying a wide range of colors including the infrared many industries couldn’t survive, important scientific achievements would not have been made. The more important it seems for this technology to be widely accessible, right?

However, today’s imaging and printing technologies able to detect infrared waves are expensive and bulky with a complex engineering prone to damages. These issues might soon be water under the bridge, due to the combination of two findings: a new way of detecting both the visible and invisible (i.e. infrared) spectrum of light, plus engineering the corresponding device.

With Existing Materials to a Cost-Effective Solution

“It’s challenging to create sensors that can detect the visible spectrum and the infrared,” says Maiken Mikkelsen, the Nortel Networks Assistant Professor of Electrical and Computer Engineering and Physics at Duke. “Traditionally, you need different materials that absorb different wavelengths, and that is very expensive. But with our technology, the detectors’ responses are based on structural properties that we design rather than a material’s natural properties. What’s really exciting is that we can pair this with a photodetector scheme to combine imaging in the visible spectrum and the infrared on a single chip.”

For this purpose, silver nanocubes of 100 nanometers are placed a few nanometers above a thin gold foil, the key lying in the size of the nanocubes as well as in the distance of the nanoparticles to each other and to the golden layer: The incoming light strikes the surface of the nanocube, trapping the light’s energy at a certain frequency. By adjusting the size of the cubes and their space to the foil, the frequency is adjusted. At the same time, the spacing between the nanoparticles allows altering the strength of the absorption. That’s how the team can make the system respond to any specific color they want.

RGB Printing Rewind

Similar types of materials have been around before, but missing an affordable corresponding technique prevented them from market entry. That’s where Mikkelsen and her team are particularly standing out. “We’ve come up with a fabrication scheme that is scalable, doesn’t need a clean room and avoids using million-dollar machines, all while achieving higher frequency sensitivities. […],” said graduate student Jon Stewart.

For the detector, Mikkelsen and Stewart patterned the nanocubes into pixels containing different sizes of nanocubes, and thus each sensitive to a specific wavelength of light. Each area responds differently to light, depending on the wavelength of light it is sensitive to. A computer then reconstructs the color of the original light.

For printing, a novel on the classic RGB scheme had been taken: The team created pixels with three bars reflecting the colors blue, green and red. By controlling the relative length of each bar, they can dictate what combination of colors the pixel reflects – even in the infrared.

“Again, the exciting part is being able to print in both visible and infrared on the same substrate,” said Mikkelsen. “You could imagine printing an image with a hidden portion in the infrared, or even covering an entire object to tailor its spectral response.”

Making this invention available surely would shake up the printing industry. How important is multispectral printing in your business? Leave us your comment below.