The tiny, soft robot walks right away after being printed. (Image Credit: University of Edinburgh)
For the first time, University of Edinburgh researchers used an open-source, customized 3D printer to create soft, tiny robots that walk after being printed. The platform can be used as a tool to address challenges associated with designing, fabricating, and adopting soft robotics. The robot doesn't require electronics or assembly to move. Instead, it relies on compressed air to walk off the print bed.
The four-legged robot is printed in just nine hours using a system called the Flex Printer, made of off-the-shelf components. This bot is made of soft, flexible thermoplastic polyurethane (TPU). The process starts off with a solid TPU filament that melts before being deposited through a print nozzle one layer at a time to form the robot's structure.
However, working with TPU is challenging as it's extremely soft. Instead of forming straight, smooth lines during printing, the material can bend unpredictably on either side. The team compares this extrusion process to pushing on a piece of string. In addition, gravity causes the molten TPU to pull downward before it turns into a solid. If this sagging occurs, it can prevent TPU layers from connecting and fusing, which presents a problem when attempting to print structures.
The team addressed the buckling by using a wider, sturdier TPU filament measuring 2.85 mm. This made the extruded material seven times more resistant to buckling. In a bit of a surprising twist, the team solved the sagging issue by flipping the 3D-printing process so that it prints from underneath.
Rather than extruding the TPU downward on a print bed, the Flex Printer deposits the material upward onto it, where the material sticks until it's detached. This works perfectly for the 3D printer since the TPU layers can press against the one above it, effectively fusing. After printing is complete, the setup is turned over to position the robot upright.
The robot is connected to a pneumatic ring oscillator that sends pulsating air bursts at 32.6 psi through its internal channels. As a result, the airflow activates two ligament actuators in both legs, forcing them to move side to side. Meanwhile, an additional actuator in the foot lifts the leg off the surface.
Even though the robot is just a proof-of-concept, the team hopes the open-source technology can progress soft-bodied robot development for applications like search and rescue, medicine, and exploration.
"Using our new platform, anyone can now easily print things which were previously thought to be impossible. This is a game-changer for engineers and artists alike. Our hope is that this technology will help drive the next wave of research breakthroughs. Without the long-standing manufacturing and design bottlenecks holding it back, we believe soft robotics is ready to make a major real-world impact," said University of Edinburgh engineer Maks Gepner.
Have a story tip? Message me at: http://twitter.com/Cabe_Atwell