Pellet Printing for Soft Robotic Devices

Area of Science:

• Robotics
• Materials Science
• Additive Manufacturing

Background:

• Traditional soft robotic device fabrication methods (manual, additive manufacturing) face limitations in material choice and post-processing.
• Existing techniques struggle with scalability and material versatility for complex soft structures.

Purpose of the Study:

• To demonstrate Fused Granulate Fabrication (FGF) as a scalable and versatile method for rapid prototyping of soft robotic devices.
• To overcome challenges in printing airtight pneumatic soft structures using FGF.
• To establish material selection guidelines for FGF based on rheological properties and performance.

Main Methods:

• Utilized a screw-based extruder for Fused Granulate Fabrication (FGF) of thermoplastic pellets.
• Implemented hardware optimization and a material-centered printing strategy to address extrusion inconsistencies and stringing.
• Conducted extrusion and oozing tests to develop material-specific performance profiles linked to rheological descriptors.

Main Results:

• Achieved reliable 3D printing of airtight pneumatic soft structures at high volumetric flow rates (up to 5 mm³/s).
• Demonstrated FGF's capability to process a wide range of materials, including soft elastomers (Shore 6A).
• Fabricated pneumatic actuators showed durability exceeding 100,000 bending cycles, with mechanical performance comparable to silicone elastomers.

Conclusions:

• FGF offers a cost-effective, scalable, and versatile alternative for digital fabrication of large-scale, airtight soft robotic devices.
• The developed material-specific guidelines facilitate material selection for optimized FGF printing.
• FGF enables the use of commercially available thermoplastic pellets, expanding material accessibility for soft robotics.