Researchers pioneer techniques to lubricate mi...( ing in their lab...)

"Since we were already using the AFM to investigate data storage devices, it seemed natural to try new applications," Bhushan said. "Friction and wear are big problems for MEMS, so I thought, why not us an AFM to study them?"

A typical AFM needle has a radius of only 50 to 100 nanometers -- a fraction of the width of a human hair. To the needle's sensitive touch, bumpy landscapes only a few atoms thick feel as expansive as mountains and valleys.

The AFM needle detected bumps on the surface of the rotor and the surrounding casing. The bumps, which ranged in size from 11 nanometers to 100 nanometers, were a normal result of the chemical process that shapes the tiny parts out of silicon, Bhushan said. Bumps on the rotor were rubbing against bumps on the casing, causing friction.

These measurements were twice as accurate as any produced by other means, Bhushan said.

The researchers were also able to gauge the amount of friction inside the motor by measuring the force required for the needle to nudge the central rotor into motion. Other researchers have tried calculating friction from indirect measurements, such as the loss of electric current flowing over a MEMS structure, but this is the first time anyone has directly measured the frictional
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Contact: Bharat Bhushan
Bhushan.2@osu.edu
614-292-0651
Ohio State University
26-Mar-2001