Scientists use synthetic muscles to control eyelids, restore ability to blink

Surgeons have demonstrated the use pf artificial muscles to control eyelids, restoring the ability to blink for those suffering from facial paralysis.

Scientists at the Medical Center of the University of California Davis used a technique that employs a combination of electrode leads and silicon polymers to activate the synthetic muscles. The development could potentially pave the way for the use of synthetic muscles to control other parts of the body.

The development could benefit patients who suffer from combat-related injuries, stroke, nerve injury or partial paralysis.

"This is the first-wave use of artificial muscle in any biological system," said Travis Tollefson, a facial plastic surgeon in the UC Davis Department of Otolaryngology, in prepared remarks. "But there are many ideas and concepts where this technology may play a role."

The technology at the center of the development is the electroactive polymer artificial muscle, or EPAM, which researchers believe they can use to create "a long-lasting eyelid blink that will protect the eye and improve facial appearance."

In the artificial muscle, developed by SRI International in the 1990s, electroactive polymers reproduce the function of human muscles by expanding and contracting based on variable voltage input levels. When a current is applied, electrostatic attractions cause the artificial muscle to expand, pulling its outer layers together. The muscle contracts when the charge is removed, flattening the shape of the sling and triggering a blink.

Blinking is a necessary function for eye maintenance. The lid wipes the surface of the eye clean and spreads tears across the cornea, which prevents the development of corneal ulcers that can eventually cause blindness.

Current eyelid paralysis treatment involves either harvesting a muscle from the leg for use in the face -- which requires six to 10 hours of surgery -- or suturing a small gold weight inside the eyelid to harness the power of gravity for blinking.

The UC Davis researchers instead used an eyelid sling mechanism made of muscle fascia or implantable fabric that blinks when actuated by a battery-powered artificial muscle.

Testing on cadavers, the researchers found that the force and stroke required to close the eyelid with the sling were within the range of the artificial muscle, and that the results showed potential for realistic movement.

While reanimating faces is the first step -- it's relatively easy to do compared to other areas of the body -- patients suffering from other types of paralysis could benefit, such as those who can no longer control their bladder or children born without the ability to smile.

The scientists estimate the technology will be available for patients in the next five years. Their findings are published in the January-February issue of the Archives of Facial Plastic Surgery.

This post was originally published on Smartplanet.com