It takes six of these muscles, arranged like the spokes of a bicycle wheel, to turn the shaft of the motor in continuous rotary motion. The muscles are attached to a central foam ring around the shaft. This foam ring is designed to replace the ratcheting mechanism used in previous devices that used electroactive polymers (EAPs) to create rotation. The new motor doesn't require any rigid pieces, greatly expanding the possibilities for artificial muscle use. For example, instruments using EAP muscles could perform less invasive surgeries, as they could squeeze through small incisions.