UCLA material scientists have developed a novel material and manufacturing method for producing artificial muscles that are stronger and more flexible than real muscles. They collaborated with colleagues at the nonprofit scientific research organization SRI International.
According to Qibing Pei, a professor of materials science and engineering at UCLA Samueli School of Engineering and the corresponding author of a study that was just published in Science, “creating an artificial muscle to enable work and detect force and touch has been one of science and engineering’s grand challenges.”
A soft material must be able to produce mechanical energy and endure significant levels of strain in order to be considered for use as an artificial muscle. It must also be able to maintain its form and strength after several work cycles.
Dielectric elastomers (DE), which are lightweight materials with a high elastic energy density and have been researched for application in the construction of artificial muscles, have caught the attention of researchers due to their superior flexibility and toughness.
Dielectric elastomers are electroactive polymers—large molecules that, when stimulated by an electric field, may change size or shape.
They may be used as actuators, transforming electric energy into mechanical work to operate machines.
Dielectric elastomers are often made of silicone or acrylic, however, both materials have drawbacks. Standard acrylic DEs are rigid and need pre-stretching, even though they can generate high actuation strain. Silicones can withstand moderate strain but are less costly to make.
Using easily accessible chemicals and an ultraviolet (UV) light curing procedure, the UCLA-led research team developed an improved acrylic-based material that is more flexible, adaptable, and simple to scale without sacrificing strength and durability.
The elastomers became softer and more flexible when the researchers altered the crosslinking between polymer strands. The creation of additional hydrogen bonds is encouraged by acrylic acid, which increases the material’s flexibility.
In order to work as an actuator by turning electrical energy into motion, the resulting thin, processable, high-performance dielectric elastomer film, or PHDE, is then positioned between two electrodes.
With a thickness of around 35 micrometers, each PHDE film is as thin and light as a human hair, and when numerous layers are stacked together, they produce a minuscule electric motor that can function like muscle tissue and provide enough energy to power motion for tiny robots or sensors.
