UCLA materials scientists and colleagues at the nonprofit scientific research institution SRI International have created a novel material and manufacturing technique for generating artificial muscles that are stronger and more flexible than organic muscles.
“Creating an artificial muscle to enable work and detect force and touch has been one of science and engineering’s grand challenges,” said Qibing Pei, a materials science and engineering professor at UCLA Samueli School of Engineering and the corresponding author of a study published recently in Science.
To be evaluated for use as an artificial muscle, a soft material must be able to output mechanical energy and stay viable under high-strain circumstances — that is, it must not quickly lose its shape and strength after repeated work cycles.
While several materials have been studied for use in the fabrication of artificial muscles, dielectric elastomers (DE) — lightweight materials with high elastic energy density — have piqued the curiosity of researchers due to their superior flexibility and durability.
Dielectric elastomers are electroactive polymers, which are big molecules that may alter size or form when activated by an electric field.
They may be employed as actuators to power machinery by converting electric energy into mechanical work.
The majority of dielectric elastomers are constructed of acrylic or silicone, however, both materials have disadvantages. While standard acrylic DEs may produce significant actuation strain, they are inflexible and need pre-stretching. Silicones are less expensive to produce, but they cannot resist tremendous strain.
The UCLA-led research team used widely accessible chemicals and an ultraviolet (UV) light curing procedure to generate a better acrylic-based material that is more malleable, tunable, and easier to scale without sacrificing strength and durability.
While the acrylic acid promotes the formation of additional hydrogen bonds, making the material more moveable, the researchers also altered the crosslinking between polymer chains, making the elastomers softer and more flexible.
The resulting thin, processable, high-performance dielectric elastomer film, or PHDE, is then placed between two electrodes to operate as an actuator by converting electrical energy into motion.
Each PHDE film is as thin and light as a human hair, with a thickness of roughly 35 micrometers, and when many layers are piled together, they form a microscopic electric motor that can operate like muscle tissue and create enough energy to power motion for small robots or sensors.
