As a child, Hod Lipson lost Lego pieces constantly. Now the 39-year-old director of Cornell University's Computational Synthesis Lab can build replacement parts on the spot. Completed last year, Lipson's fabrication machine, called a "fabber," can print thousands of three-dimensional objects, everything from toy parts to artificial muscles, using dozens of materials, including PlayDoh, peanut butter and silicone, by following simple directions sent to it by a PC.

On March 7, 17-year-old high-school student Panna Felsen squared off against three stalwart competitors in the first-ever human-robot arm-wrestling match. Each of the robots was powered by a distinct variety of electroactive polymer, also known as artificial muscle. The contenders varied in size and shape, and their creators’ budgets ranged from $800 to roughly $250,000.

The competition was designed to promote the development of materials that could someday animate prosthetic limbs, shape-shifting airplane wings and a host of other devices.

Brain chips that enable us to control machines with our thoughts. Kidneys and lungs built to order in the lab. Pills to make you smarter and more creative. An implant that gives you a tan and protects against skin cancer. All these innovations are in development; some are already being tested on human subjects.

The next technological frontier will be our own bodies. Genetics, materials science, tissue engineering and nanotechnology are already yielding products to help the sick and injured, including a Band-Aid-like heart patch and the C-leg prosthesis for amputees.

In 1999, Yoseph Bar-Cohen of NASA's Jet Propulsion Laboratory challenged the engineering world to an arm-wrestling contest. Sort of, anyway. He doesn't plan on participating himself, and the arm, which will face off against a human opponent of middling strength, has to be robotic. The catch is, he's not asking for your standard metallic appendagethis robotic arm must be built with electroactive polymers (EAPs).

Last year more than 1 million Americans had their eyes zapped with lasers to free themselves from eyeglasses. For the majority, the procedure was a success-but not for everyone. People who are farsighted, for instance, don't generally have great results. Many experience side effects such as seeing halos around objects. And laser surgery won't help people who need reading glasses because their vision continues to deteriorate as they age. So Mohsen Shahinpoor of the University of New Mexico decided to come up with an alternative.