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Robotic Lenses Controlled by Muscles

Soft robotic lenses that can zoom in and out at the blink of the human eye have been developed by a research team from the University of California San Diego (UCSD). With potential for ultimate integration into glasses or even within artificial eyeballs, the system could have a range of possible applications in the medical world.

Dr Shengqiang Cai, Associate Professor, Department of Mechanical and Aerospace Engineering, UCSD, said:

“The system developed in our work has the potential to be used in visual prostheses and adjustable glasses. If the soft robotic lens can be integrated with glasses, the glasses can be simply tuned by eye motions.”

The prototype system responds to the electric signals generated around the eyes during movement, called electrooculographic signals. Patches of monitoring electrodes are attached to the skin around two eyes: signals generated by the motion of the eye muscles are designed to mimic how the human eye works.

If the wearer blinks twice, the lens zooms in and out; if they look left, right, up or down, the lens follows. Dr Cai explained:

“The signals generated by the eye movement are used, after signal processing, to control the way of applying voltage to different regions of electroactive polymers. The voltage-induced deformation of the electroactive polymers determines the action of the robotic

A Soft Option

The soft lens itself is made up of salt water encased within two electroactive elastomer films that act like muscles. They can expand, contract, or change their structure when an electrical potential is applied. This enables the lens to look in four directions and change its focal point. Because the lens is made of soft materials, it can change its focal length by as much as 32%.

The project started roughly two years ago, with the aim of creating a proof-of-concept demonstration of a human-soft machine interface. The next steps, said Dr Cai, are to improve the system by developing wireless communication between the human eye and robotic lens and reducing the size of the lens. He added:

“We also intend to look at other types of human-soft machine interfaces, such as EEG [electroencephalogram] signal-controlled, soft robotic grippers. I hope our demonstrations will be interesting to potential industry partners, who can make use of some of our ideas to create novel products in a few years.”