Wednesday, September 7th, 2011

A Polymer That Turns Voltage Into Movement Is Moving Computer Gamers


Electroactive polymers that expand or contract when voltage is applied have been under development for a couple of decades, often referred to as artificial muscles because they were initially expected to move the arms of robots. They may yet do that but the first electroactive polymer (EAP) application on the market is moving computer game players – physically and even emotionally.

Diagram of electroactive polymer actuator.

Applying voltage to elastomeric EAP film flattens it, and expands it horizontally.

What EAPs provide to players using touch-screen game systems is haptic (sense of touch) feedback directly linked to the game features. If something explodes or shakes, the player feels it, and really excited gamers at this year’s Consumer Electronics Show (CES). Other feedback systems use preset vibrations old hat to gamers. The EAP-based feedback was so much more realistic that it wowed them They said it took their gaming to a whole new level.

The gamers were playing on an Apple iPod Touch, but the thrills were supplied from the Mophie Pulse case holding the iPod, which not only sends haptic feedback to the player’s hands, but adds stereo speakers to compound the effects.

The magic that lets the Mophie Pulse thrill the gamers is an EAP-based technology system called ViviTouch from Artificial Muscle Inc. (AMI; Sunnyvale, CA), a subsidiary of Bayer MaterialScience, which developed and supplies the EAP material. In the early 1990s, several government agencies approached SRI International (Menlo Park, CA), then known as Stanford Research Institute, looking for a more efficient actuation technology than the electro-magnetic type then commonly used in robotics.

Diagram of ViviTouch EAP actuator in iPod Touch

The ViviTouch actuator containing the EAP material is a fraction of a millimeter thick.

The resulting technology, now commercialized exclusively by Artificial Muscle Inc., consists of a thin layer – tens of microns thin – of dielectric EAP film sandwiched between electrodes. Voltage is applied across the electrodes, causing them to attract each other, which contracts the film’s thickness and expands its area. Response time is fast and, compared with other technologies, the EAP achieves significant motion with less power.

AMI uses cast films of silicone or polyurethane that are tens of microns thin, which is very thin indeed.

Artificial Muscle says the entire ViviTouch package is only a fraction of a millimeter thick, which makes it easy for designers to customize the EAP technology for their applications. The company is currently collaborating with partners in sectors including medical products, vehicle control panels and GPS touchscreens, Braille, and consumer electronics such as mobile computing handsets/smartphones and tablets. AMI expects more mobile computing and video game products to launch in the next year.

The Economist magazine’s Technology Quarterly of September 3, 2011  duly noted the many opportunities for electroactive polymer as a replacement for motors, particularly in small applications like mobile devices or autofocus  lenses. It also noted how, like any motor, artificial muscle could be used in reverse, transforming movement into electricity.

Dirk Schapeler, CEO of Artificial Muscle, tells us that reversing the process to create energy from kinetic motion is another AMI development, and that the company is currently developing EAP generators to harness both wind and wave energy.

We can add ViviTouch to the long list of emerging technologies in which plastics is the key enabler.

Mophie Pulse adds haptic feedback to iPod Touch for gaming.

The Mophie Pulse cradling the Apple iPod Touch brought new level of tactile feedback to gamers and drew two best-in-show awards at the Consumer Electronics Show.

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