Engineers have created a highly effective way to paint complex 3D-printed objects, such as lightweight frames for aircraft and biomedical stents, that could save manufacturers time and money and provide new opportunities to create “smart skins” for printed parts.
Conventional sprays and brushes can’t reach all of the nooks and crannies in complex 3D-printed objects but the new technique coats any exposed surface and fosters rapid prototyping. The technique is a more efficient way to coat not only conventional objects but even hydrogel soft robots. The coatings are robust enough to survive complete immersion in water and repeated swelling and de-swelling by humidity.
The engineers discovered new capabilities of a technology that creates a fine spray of droplets by applying a voltage to fluid flowing through a nozzle. This technique — electrospray deposition — has been used mainly for analytical chemistry. But in recent decades, it has also been used in lab-scale demonstrations of coatings that deliver vaccines, light-absorbing layers of solar cells, and fluorescent quantum dots (tiny particles) for LED displays.
Using the approach, engineers are building an accessory for 3D printers that will, for the first time, allow automated coating of 3D-printed parts with functional, protective, or aesthetic layers of paint. The technique features much thinner and better-targeted paint application using significantly fewer materials than traditional methods. That means engineers can use cutting-edge materials, such as nanoparticles and bioactive ingredients, that would otherwise be too costly in paints.
Next steps include creating surfaces that can change their properties or trigger chemical reactions to create paints that can sense their environment and report stimuli to onboard electronics.