Fundamentals and working mechanisms of artificial muscles with textile application in the loop

Abstract

Natural muscles, that convert chemical energy derived from glucose into mechanical and thermal energy, are capable of performing complex movements. This natural muscle power was the only way to perform mechanical work in a targeted manner for millions of years. In the course of thousands of years of technical development, mankind has succeeded in harnessing various physical and chemical phenomena to drive specific mechanical processes. Wind and water power, steam and combustion engines or electric motors are just a few examples. However, in order to make the diversity and flexibility of natural motion patterns usable for machines, attempts have been made for many years to develop artificial muscles. These man-made smart materials are able to react to environmental conditions by significantly changing their shape or size. For the design of effective artificial muscles that closely resemble the natural original, the usage of textile technology offers great advantages. By means of weaving, individual actuators can be parallelized, which enables the transmission of greater forces. By knitting the maximum stretching performance can be enhanced by combining the intrinsic stretching capacity of the actuators with the structural-geometric stretching capacity of the fabric. Furthermore textile production techniques are well suited for the requirement-specific, individual placement of actuators in order to achieve the optimal geometry for the respective needs in every load case. Ongoing technical development has created fiber based and non-fibrous artificial muscles that are capable of mimicking and even out-performing their biological prodigy. Meanwhile, a large number of partly similar, but also very different functional principles and configurations were developed, each with its own specific characteristics. This paper provides an overview of the relevant and most promising technical approaches for realising artificial muscles, classifies them to specific material types and explains the mechanisms used as well as the possible textile applications.

Electroactive Polymer-Based Composites for Artificial Muscle-like Actuators: A Review

“…The ratio of each component in the electrostrictive graft elastomers and the preparation conditions have the main effect on the obtained properties. For example, a higher obtained elongation at constant electric field strength can be achieved by increasing the ratio of the polar grafted groups or by increasing the material crystallinity by annealing it for a long time [41]. In reference [42], the authors investigated poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) as an active layer in the soft actuators.…”

Continuous textile manufacturing method for twisted coiled polymer artificial muscles

“…6 While shape-memory alloys or polymers, pneumatic, hydraulic, and dielectric elastomer actuators are established actuator types in the field of soft robotics, they all have significant drawbacks. 7 For example, they may require large peripheral equipment or be limited in maximum strain, force, or durability. 8 Fiber-based (textile-processable) actuator materials are particularly interesting for biomimetic structures as they allow the use of established, highly effective textile manufacturing techniques 9 and can be very similar to human muscle tissue with bundled muscle-like actuators and a soft tissue or elastomer matrix around them.…”