The new muscle for cars.

One of the stranger and more promising technologies that SRI (Menlo Park, CA), the wide-ranging technology development firm, is developing For automotive applications is artificial muscles. Dubbed "muscles" because they perform work in a similar manner to their biological namesakes, they are actually films of electroactive silicone or acrylic polymers that flatten and stretch up to three times their original size in the presence of an electric current. SRI originally developed them for use in lightweight military robots that can slither over mines without setting them off, or hover quietly like hummingbirds to spy on enemies. That's when researchers found that electroactive polymers far outdistanced other technologies when it came to power to weight ratios. In addition the polymers are cheap to produce (dollars per pound), can perform well at both very high and very low temperatures and tolerate exposure to moisture, fuels and oil. All of which make them tailor-made for the automotive environment.

Peter Marcotullio, SRI's director of business development, says that electroactive polymers can replace the dozens of conventional valves, motors, pumps and dampeners on cars at the same cost and at a Fraction of the weight. "Artificial muscles weigh about 1/50 of a solenoid that produces a similar amount of energy," he says, "and about 1/30 the weight of an electric motor." He estimates that replacing electric motors alone with artificial muscles could save about 50 pounds per vehicle.

And in an industry where engineers wage pitched battles over ounces, that's a very persuasive number.

In the engine room, Marcotullio says that SRI's polymers offer the potential of achieving what solenoids have been unable to do--a camless engine. Not only are they far more energy efficient, but they offer adjustable proportional movement, unlike solenoids' limited on/off modes. "Artificial muscles can remove the need for cams and actuate based on engine characteristics, or ambient temperature or power vs. economy' settings," he says, "making the engine completely tunable and infinitely variable." That may be a bit of a stretch, at least in the near-term. But any technology that can plausibly offer greater flexibility and drastically less complexity than current variable valve timing systems deserves a serious look.

Marcotullio says that eletroactive polymers also can be used to replace audio speakers. The polymer versions would weigh far less, and allow greater design flexibility. "Designers can put the speaker anywhere they want, in any shape they want on any surface they want," he promises.

SRI is currently working on artificial muscle projects for about a dozen OEMs and Tier 1 suppliers in the automotive industry. Though he won't divulge any details or customer names, Marcotullio says project areas include: interiors, suspensions, engines and exhaust systems. In addition, a lot of the research is focusing on active noise and vibration dampening activities. The first vehicle to utilize the artificial muscle technology is set to debut in the 2007 model year. It could be the beginning of a whole new definition for the term "muscle car."