Monolithically Printed Pneumatic Proprioceptive Actuator with Integrated Optical Waveguide Using a Single Material.

Area of Science:

• Soft robotics
• Biomimetic engineering
• Materials science

Background:

• Muscle tissues integrate force generation and proprioceptive feedback through fibers, spindles, and connective tissues.
• Existing soft robotic actuators often lack integrated sensing capabilities, limiting their functional complexity.
• Monolithic fabrication of integrated actuation and sensing remains a significant challenge in soft robotics.

Purpose of the Study:

• To develop a single-material fabrication method for monolithic pneumatic proprioceptive actuators (MPPPAs).
• To leverage thermoplastic polyurethane (TPU) for creating integrated, reliable soft robotic components.
• To demonstrate the actuation and proprioceptive sensing capabilities of the fabricated MPPPAs.

Main Methods:

• Utilized fused deposition modeling (FDM) 3D printing with thermoplastic polyurethane (TPU).
• Developed a continuous printing process to create airtight chambers and embedded optical waveguides.
• Optimized printing parameters to ensure chamber integrity and waveguide stability.

Main Results:

• Achieved highly densified, airtight chambers with minimal leakage (0.85% at 200 kPa).
• Demonstrated robust proprioception from optical waveguides with <0.5% drift over 5000 bending cycles.
• MPPPAs exhibited reliable actuation-sensing performance with sensing errors below 1.82%.

Conclusions:

• The proposed FDM-based monolithic printing method enables streamlined fabrication of MPPPAs.
• The developed actuators show high reliability and accuracy in both actuation and proprioceptive sensing.
• This advancement contributes to the development of more sophisticated and reliable soft robotic systems.