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Microscope probe-sharpening technique improves resolution, durability

A simple new improvement to an essential microscope component could greatly improve imaging for researchers who study very small things, from cells to computer chips, according to Joseph Lyding, a professor of electrical and computer engineering at the University of Illinois.

Lyding led a group that developed a new microscope probe-sharpening technique. The technique is described in research published this week in the journal Nature Communications.

In this video, Lyding explains the new microscope probe-sharpening process.


champaign probe

A traditionally etched tungsten STM probe, sharpened to a 1nm point after bombarding it with ions. Photo credit: Joseph Lyding.

Scanning probe microscopes provide images of tiny structures with high resolution at the atomic scale. The tip of the probe skims the surface of a sample to measure mechanical, electrical or chemical properties. Such microscopes are widely used among researchers who work with tiny structures in fields from nanotechnology to cellular biology.

To shape tips, researchers shoot a stream of ions at the tip. The material sputters off as the ions collide with the tip, whittling away the probe.

One day in the lab, after a tip failure, Lyding decided to apply a matching voltage to the tip to deflect the incoming ions, according to the university. When a voltage is applied to a sharp object, the electrical field gets stronger as the point narrows. Therefore, ions approaching the sharpest part of the electrified tip are deflected the most.

“This causes the ions to remove the material around that sharp part, not on the sharp part itself, and that makes it sharper,” Lyding said. “You preserve the point and you sharpen what’s around it.”