Experts from the laboratory of controlled bionic systems at Sechenov University have developed artificial muscles based on polyvinyl alcohol hydrogel activated by alternating current. This issue was told to socialbites.ca at the First Moscow State Medical University named after him. Sechenov.
The developed muscles consist of actuators; these are parts of the mechanism that can contract, bend or expand. Previously, actuators had low response speed and could easily fail when the electrical voltage was exceeded.
To solve these problems, scientists have developed actuators based on polyvinyl alcohol hydrogel activated by alternating current. When exposed to alternating current, the ions do not move towards the electrodes, but oscillate in place, so that the entire hydrogel is heated evenly and the shape of the actuator changes. It takes about three seconds to achieve the desired effect.
“Hydrogels consist of a polymer of polyvinyl alcohol and water. When we apply alternating current to the hydrogel, water ions begin to vibrate locally, causing the entire hydrogel to heat up. As a result of heating in a certain temperature range, water suddenly turns into a gas and separates from the hydrogel. When the flow stops, water is quickly reabsorbed. The hydrogel is covered with an elastic, sealed shell that expands like an inflated balloon during the process. Tarek Dayyub, senior researcher at the laboratory of controlled bionic systems, explained to socialbites.ca: In order for the expansion to occur linearly, we used two types of external reinforcing mesh: woven and spiral.
To control the change in shape, scientists used an elastic material and two types of external reinforcing mesh with special weaving geometry. A spiral web actuator can stretch up to 60%, while a woven web actuator can contract more than 20%.
It turns out that the muscles are light and quiet, have good mechanical properties and can withstand heavy loads. These will be useful not only for creating bionic prosthetics and rehabilitation devices in the medical field, but also for tasks in soft robotics and the aerospace industry.
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