Microscope probe-sharpening to improve imaging

A simple new improvement to an essential microscope component has been developed to greatly improve imaging for researchers, Laboratory Talk reports.

Joseph Lyding, a professor at the University of Illinois, led a group that developed a new microscope probe-sharpening technique. The technique is described in research published in the journal Nature Communications.

According to The Engineer, 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 structures in fields from nanotechnology to cellular biology.

According to the university, labs can spend hundreds of thousands of dollars on an elegant instrument, for example, a scanning tunnelling microscope (STM) or an atomic force microscope (AFM), yet the quality of the data depends on the probe.

Conventional techniques to sharpen probes involve bombardment of the tip with a stream of ions that cause the probe material to sputter off, AZoNano writes.

During one such probe-sharpening exercise, Lyding decided to apply an equivalent voltage to the tip to ward off the incoming stream of ions. Electric field is stronger around sharp objects. So the maximum deflection of ions was at the tips, which resulted in the removal of material around the tip while keeping the tip intact otherwise.

Lyding's team demonstrated the process by using an ion gun and was able to sharpen a 100 nm STM probe to 1 nm. In order to prevent further deterioration of the sharpened probe, the team applied a coating of hafnium diboride commonly used for silicon semiconductors. The metallic coating paved the way for durable and stable probes. The researchers have received a patent for their new and improved probes and are ready to commercialise the same.