New Deployable Adhesive Web-slinging Technology
Researchers at Tufts University have created a web-slinging adhesive technology in which a fluid material can shoot from a needle, immediately solidify as a string, and adhere to and lift objects. These sticky fibers, created at the Tufts University Silklab, come from silk moth cocoons, which are boiled in solution and broken down into their building block proteins called fibroin. The silk fibroin solution can be extruded through narrow bore needles to form a stream that, with the right adhesive additives, solidifies into a fiber when exposed to air.
Nature is the original inspiration for deploying fibers of silk into tethers, webs and cocoons. Spiders, ants, wasps, bees, butterflies, moths, beetles, and even flies can produce silk at some point in their lifecycle. Nature also inspired the Silklab to pioneer the use of silk fibroin to make powerful glues that can work underwater, printable sensors that can be applied to virtually any surface, edible coatings that can extend the shelf life of produce, a light collecting material that could significantly enhance the efficiency of solar cells and more sustainable microchip manufacturing methods.
However, while they made significant progress with silk-based materials, the researchers had yet to replicate the mastery of spiders, which can control the stiffness, elasticity, and adhesive properties of the threads they spin.
A breakthrough came about purely by accident. “I was working on a project making extremely strong adhesives using silk fibroin, and while I was cleaning my glassware with acetone, I noticed a web-like material forming on the bottom of the glass,” said Marco Lo Presti, research assistant professor at Tufts.
When the organic solvent wash was mixed in quickly, the silk solution rapidly created fibers with high tensile strength and stickiness. Dopamine and its polymers employ the same chemistry used by barnacles to form fibers that stick tenaciously to surfaces.
The next step was to spin the fibers in the air. The researchers added dopamine to the silk fibroin solution, which appeared to accelerate the transition from liquid to solid by pulling water away from the silk. When shot through a coaxial needle, a thin stream of the silk solution is surrounded by a layer of acetone which triggers the solidification.
Source: Tufts University