Scientists have achieved what they call the “holy grail” of soft robotics: creating flexible, four-legged robots that autonomously walk straight out of the 3D printers that make them.
The palm-sized devices, made entirely from soft plastic and powered by compressed air, represent a major breakthrough in manufacturing intelligent machines without electronic components.
Researchers at the University of Edinburgh developed an innovative upside-down printing technique using their new “Flex Printer” system—a low-cost, open-source platform that can be assembled for less than £400 using off-the-shelf parts. The achievement marks the first time anyone has successfully printed a robot capable of walking off the print bed immediately after fabrication.
Revolutionary Upside-Down Printing
The breakthrough came through printing ultra-flexible materials in an inverted orientation, which the team discovered enables entirely new capabilities for soft robotics manufacturing. Traditional 3D printing of flexible materials faces fundamental challenges—the ultra-soft filaments easily buckle and jam when pushed through heated nozzles, creating unreliable results.
“It used to take years to figure out how to print using these materials,” explained Maks Gepner, the lead engineer from the University’s Schools of Engineering and Informatics. “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.”
The upside-down approach solves multiple technical problems simultaneously. Gravity now helps stabilize vertical structures under tension rather than causing them to buckle under compression. This enables printing of thin membranes crucial for fluidic systems, while also allowing much longer unsupported spans without the sagging that typically ruins flexible prints.
Breaking Down Barriers
Soft robotics has enormous potential for applications in nuclear decommissioning, biomedical devices, and space exploration—environments where traditional rigid robots struggle. These flexible machines present no spark risk and remain unaffected by ionizing radiation or high magnetic fields, making them ideal for hazardous conditions.
However, progress has been limited by expensive, specialized equipment often costing over $100,000, extensive technical expertise requirements, and lack of standardized manufacturing processes. The Flex Printer addresses these barriers by democratizing access to the technology.
The team’s innovations include several key hardware modifications:
- Wider filament diameter: Using 2.85mm instead of 1.75mm filament makes the material about seven times harder to buckle, nearly eliminating jamming issues
- High-speed printing: Accelerations up to 10,000 mm²/s and travel speeds over 500 mm/s minimize material oozing without requiring complex retraction settings
- Specialized surfaces: Polyetherimide sheets provide excellent adhesion, eliminating the need for heated beds even when printing upside down
- Optimized cooling: Open design with large fans enables faster, more reliable printing of complex geometries
Walking Into the Future
The demonstrated robot incorporates embedded fluidic logic—essentially pneumatic circuits that control its movement without any electronic components. At its core lies a CMOS pneumatic ring oscillator that generates a three-phase pressure signal, coordinating the robot’s gait through “ligament” actuators that move each limb laterally and “foot” actuators that lift limbs off the ground.
What makes this achievement particularly significant is the robot’s bill of materials: just one line listing flexible TPU filament. This simplicity offers profound manufacturing advantages including supply chain resilience, fewer failure points, and potential for complete recyclability into new filaments—enabling a truly circular economy for robotics.
The robot operates at 2.25 bar pressure and successfully demonstrated walking off the print bed while still suspended upside down, then continuing to walk after being reoriented upright. This capability had been a long-sought milestone in the field.
Open Source Innovation
Rather than keeping their breakthrough proprietary, the Edinburgh team has made all designs publicly available through GitHub and established collaborative channels through the IEEE Technical Committee for Soft Robotics. They’ve also created “The Bestiary of Fluidic Machines”—an online repository for sharing reusable fluidic system components.
“Our hope is that this technology will help drive the next wave of research breakthroughs,” noted Gepner. “Without the long-standing manufacturing and design bottlenecks holding it back, we believe soft robotics is ready to make a major real-world impact.”
The open-source approach aims to foster community-driven innovation rather than competitive secrecy. First-time users can reportedly assemble the system and begin making robots within just a few days, dramatically lowering the expertise barrier that has historically limited the field.
Beyond the Laboratory
The implications extend far beyond academic research. Standardized, low-cost manufacturing could finally enable soft robotics to transition from laboratory curiosities to practical applications. The team envisions robots printed and deployed directly at point of use—whether in oil and gas facilities, nuclear cleanup sites, or even inside MRI machines where traditional electronics would fail.
The researchers acknowledge their work represents just the beginning of what they hope becomes a standardized foundry process for soft robotics, similar to how standardization enabled the microelectronics revolution. Future developments may include closed-loop printing control, multi-material capabilities, and further automation of maintenance procedures.
By solving fundamental manufacturing challenges, the Flex Printer platform could shift focus from figuring out how to make soft robots to exploring innovative applications that benefit society. The technology promises to transform not just robotics research, but potentially entire industries where gentle, adaptable machines could revolutionize human-machine interactions.
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