Mark Megahan
Researchers on the razor’s edge of high tech design engineering at MIT came up with a way to whip up a batch of muscles in the lab for aerial micro-robots. They’re proudly showing off what they can do with “low-voltage, power-dense and high-endurance artificial muscle-like actuators.”
Elastomer wing muscles
Microbots equipped with these artificial muscles have extensively improved payload. The MIT design allows a device which weighs about one-fourth that of a penny, equipped with four insect-like wings, to “hover for twenty seconds.”
That might not sound like much but it’s “the longest ever observed by this kind of robot.” Each wing gets it’s own actuator.
Each of the microbot’s muscles is “constructed from layers of elastomer fastened between two extremely thin electrodes and then wrapped into a squishy cylinder.”
When voltage is applied to the electrodes, the elastomer contracts causing “mechanical strain” which flaps the wings.
The scientists won’t have to send their microbots to they gym to build their muscles. They found out “the bigger the surface area the actuator has, the less voltage is demanded.”
That led to the use of “as many ultrathin layers of elastomer and electrode as they could.” The end result was optimized as “record-breaking insect-sized flying microrobots.” A little cosmetic work and you might think one was a dragonfly. DARPA will be working on that challenge.
Reinventing the wheel
At MIT they love to think so far outside the box there is no box. Reinventing the wheel is an everyday occurrence for them so they can avoid repeating mistakes of the original design. This time, they reinvented “parts of the fabrication process.”
To get to the point they could start spinning muscles in the lab, first they had to “form an actuator of 20 layers, each of which is 10 micrometers in thickness (about the diameter of a red blood cell).” After that, they “had to overcome a major issue caused by the spin coating process.” Air bubbles kept popping up which they cured through an extra “vacuuming process immediately after the coating, while the elastomer was still wet.”
What they ended up with was a more efficient design which lets them “build soft actuators that operate with 75 percent lower voltage than previous versions while carrying 80 percent more payload.”
In practical terms, that means “artificial muscles with fewer defects, increasing the power output.” The new design works so well that the payload is up by more than 300 percent. It also lasts a lot longer.
Now that they have a working model, microbots powered by artificial muscles weighing less than a gram far “exceed the performance of rigid robots.”
They already have plans to improve the design even further by building the actuators in a cleanroom to “eliminate issues caused by dust and air pollution and allow them to use methods that are more precise than spin coating.“
