Materials scientists have recently developed a variety of cutting-edge materials that can be used to create new technologies such as soft robotics, controllers and smart textiles. Among these materials are artificial muscles, structures that mimic biological muscles in shape and potentially improve robot movement or make it possible to design clothing that can adapt to a variety of weather conditions.
A group of scientists from Jiangnan University in China have created new artificial muscles based on free-standing, single-stranded wool yarn as part of an ongoing effort focused on textile-based soft actuators. artificial muscles, Smart Materials and Structures It can be used to quickly and inexpensively build bent actuators that can sense and respond to humidity in their environment, as described in an article published in
According to Fengxin Sun, one of the study's authors, “textiles range from microscales (eg, molecular chains and cluster structures) to macroscales (eg, fiber morphology and textile architectures).” “It is still difficult to realize a thread-based artificial muscle with a free-standing and single-helix design with a simple and environmentally friendly manufacturing technique.”
The main goal of Sun and colleagues' recent work was to address some of the problems that often arise when constructing artificial muscles from yarn (i.e., spun yarn). Most importantly, previous research has shown that it is extremely difficult to reliably twist the thread to create self-contained artificial muscle structures without the use of potentially dangerous chemicals or methods.
However, Jiangnan University researchers were able to pinpoint an environmentally acceptable treatment method for the reliability of single-stranded-strand-based muscle production. Manufacturing methodologies combine plasma etching with UV light, a plasma processing procedure often used to build integrated circuits.
This processing method can reduce energy loss from wool fibers by improving the training performance of artificial muscles. It is also efficient, adaptable and easy to use, making it ideal for the industrial production of these muscle-like structures.
Sun stated that the wool yarn artificial muscles he and his team developed exhibit reversible torsional motion when exposed to alternating moist and dry environments. “Due to the increased hygroscopic expansion of highly spun wool after wetting, the yarn muscles exhibit an extraordinary torsional motion. The reshaped disulfide meshes provide the wools with a solidified helical topology that gives the woolen yarns a “shape memory effect”.
Thanks to the creative design and production method the researchers used, the yarn that forms the artificial muscle structure can regain its original spiral shape when dried, eliminating the need for an external spring integration. In preliminary experiments, moisture sensitive, reversible and high humidity actuation performance of single helix-based muscles was demonstrated.
Surprisingly, Sun and colleagues' manufacturing process is also environmentally friendly because it does not require any hazardous or chemical additives. Its artificial muscles can be used to develop more environmentally friendly technologies and smart fabrics because wool is naturally biodegradable and reusable.
We use the inter-bond effect of reformed disulfide bridges in the helical structure state of the wools to stabilize the twists added to the yarn muscles through UV light illumination and autooxidation. Single helical structures are typically thought to be unstable and prone to twisting without external torsion bonding. This method significantly improves the running performance of woolen yarn muscles and is completely harmless to the environment.
Future work by this team of scientists could serve as an inspiration for the creation of new thread-based actuators and synthetic muscles for robots that can be made large-scale, cost-effectively and sustainably.
They have also produced single-stranded wool yarn that can be used to make textiles for smart clothing, smart camping equipment, and other smart textiles that are comfortable, breathable, non-toxic, and good for the skin.
To realize the mass production of yarn muscles for practical use in smart textiles and to encourage technological innovations, Sun said, “In the next phase of our research, we will explore the path to industrial production of our artificial muscles.”
Imagine a garment with threads that can cleverly change the air grips on the fabric to adapt to a variety of weather conditions. We hope to find affordable versions of these clothes in our daily lives.”