Originally Published MPMN January/February 2008

NEED TO KNOW

Researchers Apply CAD to Nanostructures

Daniel Grace

An automated technique for nanomanu­facturing could allow engineers to apply macro techniques on the nano scale, according to researchers from Duke University (Durham, NC; www.duke.edu). Researchers Rob Clark—a professor of engineering—and Matthew Johannes—who recently received his doctoral degree from Duke—have adapted a long-standing computer-aided design (CAD) and manufacturing process to reproduce 3-D nanosized structures with features on the scale of single molecules.

Researchers used the traditional language of macroscale milling machines to guide an atomic force microscope (AFM). The system reliably produced nanometer-scale silicon oxide nanostructures through a process called anodization nanolithography, in which oxides are built on semiconductor and metallic surfaces by applying an electric field in the presence of trace amounts of water.

AFMs can produce images and manipulate individual atoms and molecules and, to date, have been the preferred instrument for those seeking to create two-dimensional patterns on metals and semiconductors on the nano scale.

“In the past, a researcher would start with a JPEG image, say, and then program the AFM to do the replicate mapping,” says Johannes. “Our advance has been to take a visualized 3-D structure, enter all the parameters, and replicate that on the nanoscale.” The resulting structures were approximately 80,000 times smaller than the diameter of a human hair.

The main challenge was controlling the conditions, Johannes says. Humidity, voltage, and scanning speed had to be regulated precisely, and the researchers were reliant on sensors to guide the otherwise invisible process.

Though manufacturing plants of the future might operate similarly to those today, the products produced could be extraordinarily different, particularly in the medical sector. “The holy grail of nanomaterial research is moving from single-tip arrays to multiple-tip arrays, with each array working in parallel and being programmed with unique functionality,” says Johannes. “Once there is that kind of massively differentiated array, it could lead to significant new medical technology, particularly with biosensors and lab-on-a-chip systems.”

Johannes says the researchers plan to make the AFM design specifications and software available free online.

Copyright ©2008 Medical Product Manufacturing News