UCLA materials scientists and colleagues at the nonprofit scientific research institute have developed a new material and manufacturing process for creating artificial muscles that are stronger and more flexible.
One of the grand challenges of science and engineering is the creation of artificial muscles to enable work and detect force and touch.
For a soft material to be considered for use as an artificial muscle, it must be able to output mechanical energy and remain viable under high-strain conditions. The lightweight materials with high elastic energy density have been of interest because of their flexibility and strength.
When stimulated by an electric field, dielectric elastomers can change in size or shape. Electric energy can be transformed into mechanical work with the help of them.
Silicone and acrylic are two materials that have drawbacks. Pre-stretching and lack of flexibility are some of the drawbacks of traditional acrylic DEs. Silicones can be made, but they can't handle high strain.
The UCLA-led research team used commercially available chemicals and an ultraviolet light curing process to create an improved acrylic-based material that is more flexible and simpler to scale. The researchers adjusted the crosslinking between thepolymer chains to make the material softer and more flexible. PHDE is sandwiched between two electrodes to convert electrical energy into motion.
When multiple layers of PHDE film are stacked together, they become a miniature electric motor that can act like muscle tissue and produce enough energy to power motion for smallrobots or sensors. PHDE films ranged from four to 50 layers.
Pei said that this flexible, versatile and efficient actuator could open the gates for artificial muscles in new generations ofrobots, or in sensors and Wearable tech that can more accurately mimic or even improve humanlike motion and capabilities.
Artificial muscles fitted with PHDE are three to ten times more flexible than natural muscles.
Multilayer soft films are usually made using a wet process. The process can result in layers that are not evenly distributed. This is the reason why single-layer DE films are the only ones that have been successful.
The UCLA research involves a "dry" process in which the films are layer by layer using a blade and then UV-cured to hardened. The device can support more complex movements if the energy output is increased.
The PHDE's flexible and durable nature, along with the simplified process, allow for the manufacture of new soft actuators capable of bending to jump, like spider legs. The PHDE actuator can toss a ball 20 times heavier than the PHDE films. A glimpse of how artificial muscles could be used in the future can be seen with the expansion and contraction of the actuator.
Soft robots with improved mobility and endurance could be the result of the advance. The manufacturing process can be used to make other soft thin-film materials.
More information: Ye Shi et al, A processable, high-performance dielectric elastomer and multilayering process, Science (2022). DOI: 10.1126/science.abn0099. www.science.org/doi/10.1126/science.abn0099 Journal information: Science
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