Friction measured on microdevices

Before microdevices can be developed into medical implants and other microscopic products, developers must first understand how friction, wear, and other forces operate on such a small scale. Bharat Bhushan, a professor of mechanical engineering at Ohio State University, is using an atomic force microscope to answer questions about wear and friction on such a small scale. Atomic force microscopes record the shapes of objects by dragging a tiny needle with a radius less than 100 nm across the surface of an object. Bhushan used the microscope on the surface of a micromotor's rotor and surrounding casing. He detected bumps between 11 and 100 nm that resulted from chemical process used to make the micromotor work for a biomedical application, and determined that the bumps on the rotor caused friction when they rubbed against the casing. When Bhushan tried lubricating the motor with a synthetic lubricant, the lubricant gummed up the tiny motor. But when they baked the motor and lubricant combination at 150C, the lubricant became a smooth layer hat allowed free movement.

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