Chemo-driven soft pneumatic actuation
: from catalysts to neutralisation reactions for oscillating pneumatic systems

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Pneumatic actuators are extensively studied in soft robotics as they are facile, low-cost, scalable, robust and exhibit compliance similar to many systems found in nature. The challenge is to harness, high energy density, chemical, and biochemical reactions to generate sufficient pneumatic pressure for controlled and biocompatible actuation of soft systems.
This study identifies and proposes a variety of gas evolution reactions (GERs) and gas consumption reactions (GCRs) as reversible power sources for soft robotic actuators. It marks the first successful coupling of both GER and GCR in actuating pneumatic soft actuators while controlling actuation over reaction rates and final pressure for efficient oscillating actuation.
Furthermore, the research introduces a catalytic FDM filament with embedded platinum nanopartocles (PtNPs) for enhanced soft pneumatic actuation, improving catalytic activity and reusability compared to commercial and synthesised dispersed nanopowders. The synthesis and characterisation of sub-3 nm PtNPs in a polymeric matrix achieve higher catalytic activity by optimising the surface-to-volume ratio of the nanoparticles. The fabrication of 3D structures with catalytic properties using additive manufacturing enables complex geometries for diverse soft robotic applications.
Moreover, an in-depth investigation of the photoreduction mechanism and in-situ generation of PtNPs in a thermoplastic polyurethane (TPU) matrix is conducted, providing insights for further development of catalytic materials. Creating high surface area structures enhances catalytic properties using the direct ink writing (DIW) method, expanding potential applications in soft pneumatic actuators. TPU Ninjaflex 3D-printed bellow-type pneumatic soft actuators demonstrate chemical resistance and mechanical suitability for coupling with the evaluated GERs and GCRs.
The thesis highlights significant progress in coupling GERs and GCRs, paving the way for innovative power sources in the soft pneumatic actuators field. This work represents a significant step towards more autonomous, versatile soft pneumatic systems driven by chemical reactions aided by smart functional materials using a variety of additive manufacturing methods.
Date of Award3 Oct 2023
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorCharl F J Faul (Supervisor), Richard S Trask (Supervisor) & Michael Dicker (Supervisor)

Keywords

  • soft robotics
  • soft actuator
  • Chemically-driven
  • Chemical reactions
  • gas evolution reactions
  • pneumatic actuators

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