Tufts Team Paves the Way for Large-Scale 3D-Printed Soft Robots

Imagine a world where anyone can print custom medical devices for themselves or their community using inexpensive desktop printers, such as a personalized pressure cuff. Or a robot that looks and moves like a fish that could unobtrusively monitor underwater populations. Or a soft robotic hand that could grip objects in a more human-like way. A Tufts team in the Nemitz Robotics Group is working to make bio-inspired robots and systems easier to manufacture through improved 3D printing techniques. The researchers addressed important 3D printing limitations in a recent Advanced Science paper titled, “Pellet Printing for Soft Robotic Devices.”  

While there are exciting possibilities in the world of soft robotics, scaling up fabrication remains a challenge. Many soft robots use an approach called soft lithography, which requires skilled operators and custom molds and is typically limited to specialized labs. The items must be extensively post-processed and assembled manually, resulting in long manufacturing times.

3D printing offers a faster and more cost-effective alternative to traditional manufacturing, but most existing systems are optimized for relatively stiff materials and face significant challenges when processing soft elastomers. Current approaches to printing soft materials often suffer from issues such as inconsistent material deposition and stringing. In this work, the Tufts group demonstrates that Fused Granulate Fabrication (FGF), an existing technique, can be adapted into a reliable strategy for soft material printing by addressing these limitations. FGF is similar to the widely-used Fused Filament Fabrication (FFF) method, but instead of using filament, it directly melts thermoplastic pellets and extrudes them through a nozzle for printing.

First author and Ph.D. student Yijia Wu worked with Assistant Professor Markus Nemitz, master’s student Ju-Hung Chen, undergraduate seniors Ariana Olivares, Katherine Kostak, and Stefan Pedicone, (all E26), and Ph.D. candidate Savita V. Kendre (all of the Department of Mechanical Engineering) to test the compatibility of soft robotic projects with desktop FGF printing. The group evaluated different materials and strategies to optimize printing.

They showcased their approach through three unique 3D-printed systems: a soft robotic hand, a robotic fish, and a blood pressure cuff monitor.  Each device was fabricated in a single print within less than a day and produced monolithically, meaning no post-assembly was required.  All three systems were printed using commercially available thermoplastic pellets. The results demonstrate that FGF can serve as a practical and scalable platform for the fabrication of soft robotic systems.

Each demonstrator tested a different aspect of soft robotics. With an intricate internal network of fifteen pneumatic actuators acting as joints, the hand was able to grasp items including a football, a tennis ball, and a screwdriver, highlighting its ability to adjust grip strength. The fish tested airtightness for potential underwater applications. Researchers compared the cuff with a commercially available blood pressure cuff and found similar performance, suggesting that FGF-printed soft robotics could be useful in medical devices.  

Beyond these three examples, the work primarily establishes the underlying methods that make reliable soft-material FGF printing possible. These advantages lay the foundation for future applications in wearable devices, assistive technology, prosthetics, and related areas. While FGF still requires further refinement, this work represents a significant step toward making large-scale soft robotic systems practical and scalable. 

This new printing technology will be introduced in Nemitz’s course ME0193: Printable Robotics in Fall 2026, where students design, fabricate, and test their own 3D-printed soft robotic systems. The course emphasizes fluidic sensing, control, and actuation, enabling students to create fully integrated, non-electronic soft robots using advanced additive manufacturing techniques. 

The Nemitz Robotics Group in the Department of Mechanical Engineering specializes in the design and implementation of scalable robotic systems. Many of their swarm robotics technologies are tailored for extreme environments to enable critical applications such as cave rescues and explosive ordnance disposal. 

Learn more about the Nemitz Robotics Group.