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Villeda-Hernandez et al. Soft Sci 2024;4:14 Soft Science
DOI: 10.20517/ss.2023.52

Review Article Open Access

Soft alchemy: a comprehensive guide to chemical

reactions for pneumatic soft actuation

Marcos Villeda-Hernandez 1 , Benjamin C. Baker 1 , Christian Romero 2 , Jonathan M. Rossiter 2 ,
Charl FJ. Faul 1,*
1
School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
2
School of Engineering Mathematics and Technology, and Bristol Robotics Laboratory, University of Bristol, Bristol BS8 1TW, UK.
* Correspondence to: Prof. Charl FJ. Faul, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK. E-mail:
charl.faul@bristol.ac.uk
How to cite this article: Villeda-Hernandez M, Baker BC, Romero C, Rossiter JM, Faul CFJ. Soft alchemy: a comprehensive guide
to chemical reactions for pneumatic soft actuation. Soft Sci 2024;4:14. https://dx.doi.org/10.20517/ss.2023.52
Received: 15 Nov 2023 First Decision: 27 Dec 2023 Revised: 31 Jan 2024 Accepted: 25 Mar 2024 Published: 29 Mar 2024

Academic Editors: Zhifeng Ren, Ramsés Valentin Martínez Copy Editor: Dong-Li Li Production Editor: Dong-Li Li

Abstract
Soft robotics has emerged as a transformative field, leveraging bio-inspired novel actuation mechanisms to enable
more adaptable, compliant, and sophisticated robotic systems. However, the portability of soft pneumatic
actuators is typically constrained by the tethering to bulky power sources. This review offers a thorough analysis of
autonomous power alternatives facilitated by chemical reactions for gas generation and absorption, a concept
analogous to biological energy conversion processes. These bio-inspired strategies propel soft pneumatic actuators
towards new horizons of autonomy and portability, essential for real-world applications. This comprehensive
review explores the critical intersection of gas evolution reactions (GERs) and gas consumption reactions (GCRs)
as a power source for pneumatic actuation in soft robotics. We here emphasize the importance and impact of bio-
inspired design, control, efficiency, safety, and sustainability within soft robotics to not only mimic biological
motions but to enhance them. This review explores the fundamentals of both pneumatic and chemically powered
actuation, highlighting the need for careful consideration of reaction kinetics. Additionally, this work highlights key
aspects of smart materials that draw from biological structures and response mechanisms, along with state-of-the-
art techniques for precise pressure modulation. Finally, we chart prospective development pathways and provide a
future outlook for bio-inspired soft robotics, emphasizing the transformative impact of integrating chemical
actuation methods. This exploration underlines the quest for further autonomy in soft robotic systems and points
towards the future opportunities in this exciting and fast-developing field.

Keywords: Soft robotics, chemistry, pneumatic actuation, design, chemical power source, oscillating systems,
chemical reactions, chemically driven pneumatic actuation

© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution 4.0
International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, sharing,
adaptation, distribution and reproduction in any medium or format, for any purpose, even commercially, as
long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and
indicate if changes were made.

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