Plant-based spray could be used in masks, electronics or human organs

A new method of spraying extremely thin wires made of a plant-based material could be used in a wide range of objects, researchers have claimed – from coronavirus mask filters to 3D-printed organs.

Developed at Rutgers University in New Jersey, the method involves spraying methylcellulose, a renewable plastic material derived from plant cellulose, on 3D-printed and other objects ranging from electronics to plants.

“This could be the first step towards 3D manufacturing of organs with the same kinds of amazing properties as those seen in nature,” said senior author Jonathan P. Singer. “In the nearer term, N95 masks are in demand as personal protective equipment during the Covid-19 pandemic, and our spray method could add another level of capture to make filters more effective. Electronics like LEDs and energy harvesters also could similarly benefit.”

Nanowires made of soft material have many applications, including the cilia that keep our lungs clean and the bristly structures that allow geckos to grip walls. Such wires have also been used in small triboelectric energy harvesters, with future examples possibly including strips laminated on shoes to charge mobile phones, or a door handle sensor that turns on an alarm.

The researchers said that while people have known how to create nanowires since the advent of candy floss melt spinners, controlling the process has always been limited. The barrier has been the inability to spray, instead of spin, such wires.

Singer's Hybrid Micro/Nanomanufacturing Laboratory, in collaboration with engineers at Binghamton University, revealed the fundamental physics to create such sprays. With methylcellulose, they have created ‘forests’ and foams of nanowires that can be coated on 3D objects. They also demonstrated that gold nanoparticles could be embedded in wires for optical sensing and coloration.

The research was published in Materials Horizons.

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