A global view of the very small
In an engineering lab at the University of Puerto Rico, Mayaguez (UPRM), a student takes pictures of a nanomaterial by controlling a microscope with a computer. What makes this scene unique is that the microscope isn’t beside the computer or even in the next room. Rather, it’s located in the basement of the UW-Madison Materials Science and Engineering Building.
Unveiled in April, the new scanning transmission electron microscope, or STEM, is one of a handful of instruments of its kind in the United States. It’s used to take high-spatial-resolution images of the atomic structure and composition of a variety of materials. The microscope’s high spatial resolution is important because the distance between atoms in most materials is two to three Ångströms. (An Ångström equals 0.1 nanometer.) Previous microscopes had a resolution of two to three Ångströms, meaning researchers could barely make out any atoms at all.
However, the new STEM has a spatial resolution of less than one Ångström, meaning researchers can take images that show where every atom in a piece of material is located, as well as what elements the various atoms are.
“This microscope gives us a level of instrumentation on par with the world-leading federal laboratories and research universities,” says Associate Professor Paul Voyles, who with Animal Sciences Professor Ralph Albrecht and Geoscience Assistant Professor Huifang Xu led the effort to bring the STEM to UW-Madison.
The STEM will aid UW-Madison researchers working on advanced metal alloys, nanoelectronic devices, catalysis, biomacromolecules and other areas. In addition to serving researchers on campus, the STEM can be operated remotely, making it a global tool. Access to a STEM is crucial for the many catalysis and nanomaterials researchers at UPRM, so the institution partnered with UW Madison on the original acquisition grant from the National Science Foundation.
Additionally, the remote operating capabilities allow Voyles and others to train a larger number of researchers to use the STEM, further expanding its impact.
Mentor for inventors
Erwin W. Mueller Professor and Bascom Professor of Surface Science Max Lagally serves as a bridge between the UW-Madison laboratories where cutting-edge technologies are developed and the companies taking those devices to market.
“When I was in graduate school during the Sputnik era, the motivation in academia was to create more academics,” he says. “That’s changed tremendously in the last 25 years, when we realized there could be economic benefits to the state and nation by taking some of these technologies and turning them into reality.”
Lagally’s first experience with a spin-off company came in the mid-1990s, when a graduate student walked into Lagally’s office looking for a job. The student eventually wrote controls software for scanned-probe microscopes under Lagally’s direction, who co-founded nPoint Inc. to market the software. The company has evolved to produce motion and nanopositioning devices and now is established as one of the most reliable producers of these technologies in the world.
“I wanted to see if I could do something that people would pay money for,” says Lagally. Once he realized he could, he determined something else: He prefers research to business. “What is exciting to me are new ideas, developments and technologies — creating stuff,” he says.
However, Lagally remains committed to technology transfer, and in 2004 he and a group of colleagues patented a microfluidic deposition system capable of depositing drops, lines and even towers of various materials in minute quantities. Some of those colleagues, including Lagally and the student involved in the project, Brad Larson, licensed the technology from the Wisconsin Alumni Research Foundation and co-founded SonoPlot to take the technology to market.
Both nPoint and SonoPlot have a global network of sales and distributors, with base operations still in the Madison area. Lagally serves as a consultant at both, but his influence on entrepreneurs is far from limited to these two companies. His experience and extensive business connections make him a mentor sought by many students planning to start their own companies. “Max provided encouragement early on,” says Larson, who is now SonoPlot’s chief technology officer. “He was different from other professors who focused on basic science and said commercialization could come later. Max always pushed us to look at what the end uses of the technology were and how it would actually make an impact on people’s lives as a product.”
Finding the right path
A team led by Professor Chang-Beom Eom has developed a new approach for creating powerful nanodevices, and the discoveries could pave the way for other researchers to begin more widespread development of these devices.
Particular metal-oxide materials have a unique magneto-electric property that allows the material to switch its magnetic field when its polarization is switched by an electric field, and vice versa. These materials can be used as bases for a variety of magnetoelectric devices that act like signal translators capable of producing electrical, magnetic or even optical responses and can store information in any of these forms.
Essentially, Eom and his team have developed a roadmap to help researchers “couple” a material’s electric and magnetic mechanisms. As researchers run a current through a magnetoelectric device, electric signals follow the electric field like a path. The signals’ ultimate destination could be, as an example, a memory “bank” operated by a magnetic field. When the researchers switch the electric field, the signals encounter a fork in the path. Though both prongs of the fork head in a similar direction, one path is the correct one and will prompt the magnetic field to switch. This will allow the information carried by the signals to be stored in the bank. If the signals take the incorrect path, the magnetic state won’t switch, the bank remains inaccessible, and when the electric field turns off the information is lost.
The team also has developed a matrix that ensures the cross-coupling effect is stable, or non-volatile, which allows for long-term data storage. This matrix is then embedded in thin films.
These two discoveries — the correct path and the stabilizing matrix — will allow other researchers to study the fundamental physics of cross-coupling in materials and begin investigating how to turn the many possibilities of multifunctional devices into reality.