(ORDO NEWS) — Researchers at the University of California, Los Angeles (UCLA) have developed a new material to create artificial muscles that are 10 times stronger and more flexible than natural muscles, the university said in a press release.
The scientists aimed to replicate the muscles, which could then be used to create soft robots and new tactile technologies. Materials scientists know of many soft materials that can do the double job of providing mechanical kickback while remaining viable under high stress conditions.
A class of materials called dielectric elastomers (DES) can provide both flexibility and strength, and are not only light in weight but also have high elastic energy density.
DES can be made from natural or synthetic compounds and are polymers that can change size or shape when an electric field is applied. This makes them ideal materials for making actuators, that is, machines that can convert electrical energy into mechanical work.
What then needs to be improved?
Currently, DES are made using either acrylic or silicone, and while they have been useful, they also have certain disadvantages.
DES made from acrylic can withstand high loads, but require pre-stretching and are not flexible. On the other hand, silicone muscles can be easily made, but they do not withstand high loads.
Working with the non-profit organization SRI International, the UCLA team used commercially available chemicals and an ultraviolet (UV) light-based curing process to improve acrylic-based DE.
The researchers were able to change the crosslinking in the material’s polymer chains to make DE softer, more flexible, and easier to build without losing toughness or strength.
Changes in the manufacturing process have allowed the researchers to create thin films of DES, which they call processable high performance dielectric elastomer (PHDE).
How can PHDE be used?
PHDE film is as thin as a human hair and equally light in weight. Layering these films could help researchers create miniature actuators that can act like muscle tissue and produce enough mechanical energy to power a small robot.
Soft materials have been layered before. However, the method used to do this involves the use of a liquid resin, which must first be applied and then cured.
This “wet” process can cause the drive to have jagged layers resulting in reduced performance. This is why the artificial muscles you may have seen in the past are only one layer thick.
UCLA researchers have also worked on this aspect and implemented a dry process in which PHDE films are laid in layers with a blade and then cured with UV light.
The simplified process has even allowed the researchers to make actuators that resemble spider legs that bend and then jump, or even curl up and then spin.
According to a press release, these new actuators can generate many times more force than biological muscles and are 3 to 10 times more flexible than their natural counterparts. In the course of the demonstration, the researchers showed that the drive could toss a ball up to 20 times its weight.
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