Carol Livermore, an associate professor of mechanical engineering, is among the pioneers of a new field: tiny energy-storing devices known as super springs.
Made of carbon nanotubes, or hollow tubes of carbon about 10,000 times thinner than a human hair, the devices could lead to smaller, longer-lasting power sources with some advantages over current batteries and other power systems. For example, this could mean that one day you could run a leaf blower without the fumes and noise.
“Any fifth grader knows that you can stretch an elastic band, store energy in it, and release that energy for some purpose — like hitting the kid in the chair next to you,” says Livermore. The principle behind her elastic band example also applies to the springs that run watches, mouse-traps, and ballpoint pens.
However, the materials like steel and rubber used in conventional springs have low energy densities, meaning they can’t store much energy for their size and weight. “That’s why you have to wind a mechanical watch every couple of days,” says Livermore.
She and colleagues have found that carbon nanotubes, in contrast, should have very high energy densities, potentially over 1,000 times those of steel and close to those of the best batteries. They also have high power densities — they can release a large amount of energy quickly. And, unlike batteries, which become harder to recharge over time, the energy stored in super springs should stay constant. Livermore says: “Think of your grandmother’s watch. It’s likely that the spring still works, and how many times has it been ‘recharged’ [rewound]?”
Livermore and her team have applied for a patent on the general technology, and are beginning to fashion nanotubes into demonstration devices. They’ve actually used super springs, for example, to run a mechanical watch and be the operative part of a miniature slingshot. Much work remains, however, before commercial applications are realized, she says. After all, “carbon nanotubes were only discovered about 20 years ago and are still a relatively new material.
“I get particularly excited about learning how the world works and putting [that knowledge] to good use,” says Livermore, who seems to have found her niche exploring and creating ultra-small systems.