Original source: Materials Today
Engineers have developed a method for spraying extremely thin wires made of a plant-based material onto 3D objects. These plant-based wires could find use in wide range of potential applications, including N95 mask filters, devices that harvest energy for electricity and even artificial human organs.
The method, which is described in a paper in Materials Horizons, involves spraying methylcellulose, a renewable plastic material derived from plant cellulose, onto 3D 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 Singer, an assistant professor in the Department of Mechanical and Aerospace Engineering at Rutgers University-New Brunswick. “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.”
Thin wires (nanowires) made of soft matter have many applications. They include such natural organelles as the cilia that keep our lungs clean and the setae (bristly structures) that allow geckos to grip walls, while similar wires have been used in small triboelectric energy harvesters. Future applications may include strips laminated onto shoes to charge a cell phone and a door handle sensor that turns on an alarm.
While people have known how to create nanowires since the advent of cotton candy melt spinners, controlling the process has always been limited. The main barrier has been the inability to spray rather than spin such wires.
Singer’s Hybrid Micro/Nanomanufacturing Laboratory, in collaboration with engineers at Binghamton University, has now uncovered the fundamental physics required for spraying nanowires. With methylcellulose, they have created ‘forests’ and foams of nanowires for coating onto 3D objects. They also demonstrated that gold nanoparticles could be embedded in the nanowires for optical sensing and coloration.