Engineers Develop Electronic Brakes for Skis

Feb. 22 -- At age 3, Ian Hussey hasn't quite developed a healthy sense of fear on the slopes.

"He doesn't like to slow down, he doesn't like to turn, he just likes to go straight ahead — fast," said Dianne Hussey about their son.

When his parents take him skiing at Sugarloaf Mountain in Kingfield, Maine, they need to hold him back with a harness. As early as next year, they might have another option: built-in brakes.

Victor Petrenko, an ice engineer at Dartmouth College's Ice Research Lab in New Hampshire, has developed an electronic braking system that can keep skis and snowboards within a pre-set speed limit.

The system uses a network of wires that are embedded into the bottom of the ski and activate charges across the snow surface. Those charges interact with charges on the snow's surface to slow the skis.

"You can adjust the addition of resistance from nothing to very high," said Petrenko. "It's not like you turn on the power and the skis stop, it happens gradually by slowly increasing the charge."

Making Skis Stick

In the one-foot-long prototypes that Petrenko and his colleagues have tested on miniature indoor laboratory ski slopes, a sensor fitted to the boards monitors the skis speed over the ice. Once the skis accelerate beyond a pre-set speed, the brakes gently activate.

The idea works thanks to the ability of ice to hold a charge and to the fact that opposites attract in the realm of physics.

One set of wires on the skis triggers a negative electric charge, which clings to positive charges on the surface of the snow. Another set fire positive charges, which attract negative charges on the snow's surface.

Petrenko explains the actual contact between ski and snow occurs only on tiny microscopic ridges on the snow's surface. When a voltage is applied between the ice and ski, the electric current crosses these tiny bumps and melts them.

As the charged is released, the water refreezes against the ski's surface and the force required to break that bond helps hold the skier back.