Pellet-based 3D Printing of Soft Thermoplastic Elastomeric Membranes for Soft Robotic Applications

2025-03-26

AI Summary

Soft robotics urgently requires ultrashort, highly extensible, and gas-tight thin-film materials. Method: This study pioneers pellet-based fused deposition modeling (FDM) of ultrashort thermoplastic elastomer (TPE) granules—bypassing conventional filament constraints—through process optimization and multimaterial co-printing (TPE granules + rigid filaments). Contribution/Results: We fabricate gas-tight films (0.2–1.2 mm thick) with elongation at break up to 1320%. We introduce a “film-based soft actuator integrated design paradigm,” unifying actuation, tactile sensing, and adaptive envelopment within a single monolithic structure. The resulting 180°-bending actuator achieves a blocking force 238 times its own weight; the tactile suction cup enables pre-contact detection and adaptive sealing grasp, significantly enhancing soft robots’ interaction capability in unstructured environments.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Machine Learning: Large Multimodal Models (LMMs)
• Philosophy and Ethics of AI: Safety, Robustness & Trustworthiness

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

Additive Manufacturing (AM) is a promising solution for handling the complexity of fabricating soft robots. However, the AM of hyperelastic materials is still challenging with limited material types. Within this work, pellet-based 3D printing of very soft thermoplastic elastomers (TPEs) was explored. Our results show that TPEs can have similar engineering stress and maximum strain as Ecoflex OO-10. These TPEs were used to 3D-print airtight thin membranes (0.2-1.2 mm), which could inflate up to a stretch of 1320%. Combining the membrane's large expansion and softness with the 3D printing of hollow structures simplified the design of a bending actuator that can bend 180 degrees and reach a blocked force of 238 times its weight. In addition, by 3D printing TPE pellets and rigid filaments, the soft membrane could grasp objects by enveloping an object or as a sensorized sucker, which relied on the TPE's softness to conform to the object or act as a seal. In addition, the membrane of the sucker was utilized as a tactile sensor to detect an object before adhesion. These results suggest the feasibility of 3D printing soft robots by using soft TPEs and membranes as an interesting class of materials and sensorized actuators, respectively.

Problem

• Exploring pellet-based 3D printing for soft thermoplastic elastomers (TPEs).
• Developing airtight thin membranes for soft robotic applications.
• Combining soft TPEs with rigid materials for sensorized actuators.

Innovation

• Pellet-based 3D printing of soft TPEs
• Airtight thin membranes with 1320% stretch
• Combined soft TPEs and rigid filaments