Volume 12, Number 2, 2003
Doug Buttrey's office is on the third floor of UD's Colburn Lab, but when a visitor comes to tour his research facility, the associate professor of chemical engineering immediately takes the elevator to the basement of neighboring Spencer Lab. Buttrey is working with some of the most high-tech, expensive equipment on campus, and he and his research team are located in the lowest part of the building.
"That's where electron microscopes need to be, as it's the most stable part of the building," Buttrey says. "This equipment operates at such a high level of precision that it's sensitive to the slightest nuances of movement and vibration--for example, from researchers talking in the lab or traffic passing by outside. If it moves by a nanometer [one-millionth of a millimeter], that's a lot."
Minor changes in temperature or humidity also affect the instruments, so the electron microscope lab is sealed and its environment carefully controlled. Formally known as the W.M. Keck Electron Microscope Facility, the lab was established in early 2001 through a generous grant from the W.M. Keck Foundation and matching funds from the University.
The electron microscopes in Spencer Lab--including the newest one, which arrived just a few months ago from Japan--are used for materials science research throughout the College of Engineering, as well as for work in other fields, including physics, chemistry and agriculture, according to Chao-Ying Ni.
Ni is in charge of the day-to-day operation of the electron microscopy facility for the College. He works with about 50 graduate students and numerous faculty members who use the lab for a variety of projects in nanotechnology and biotechnology. The lab is overseen by a committee made up of Buttrey; Ni; Darrin Pochan, assistant professor of materials science and engineering; and Ian "Rick" Hall, associate professor of mechanical engineering.
"Anyone who's interested in the morphology, structure and composition of materials at the atomic or molecular level, ranging from biomedical applications to chemical processing and colloidal science, needs the type of information that this equipment can provide," Ni says.
Electron microscopes are similar to the more familiar light, or optical, microscope, but they are capable of far higher resolution. Optical microscopes magnify objects using a series of glass lenses and a beam of light that either travels through a sample from below or reflects it from above. Their magnification capabilities are limited by the wavelength of light used, and even the best ones can usefully magnify objects only about 2,500 times.
To detect items smaller than the wavelength of visible light (roughly 500 nanometers), an electron microscope instead focuses an electron beam (with a wavelength less than one-hundredth of a nanometer, or smaller than an atom) to create an image of the sample being studied. Because of this difference, electron microscopes can attain useful magnification of the order of about 1 million, meaning that some instruments are capable of imaging individual atoms.
X-ray detectors on these high-end scopes enable heavy elements to be separated out from lighter ones. "We can, for example, see exactly where the cadmium is in a given sample by conducting a computer analysis of the image," Buttrey says.
The cost of electron microscopes ranges from several hundred thousand dollars to more than $1 million. A single specialized sample holder can cost $50,000, and an X-ray detector can add another $80,000 to the price tag.
The cost is well worth it in terms of what the technology enables scientists and engineers to do, Buttrey says.
The College's electron microscope lab has five instruments. Three, including the newest one, are scanning electron microscopes (SEMs), in which the electron beam strikes the sample and bounces back. The other two, including the most advanced one, are transmission electron microscopes (TEMs), in which electrons pass through the sample. The transmission type is larger and operates at a much higher voltage. The latest versions of both types of microscopes are highly computerized and feature digital controls and multiple computer screens on which images can be displayed to show the composition of the sample.
The new TEM cost a total of about $1.5 million, much of it funded by the W.M. Keck Foundation. The newest SEM, which cost almost $500,000, was funded by the National Science Foundation's Major Research Initiative.
The technology has numerous applications, including industrial use and medical research.
"For example, the element osmium is highly toxic when it forms an oxide and would be lethal if inserted directly into the human body," Buttrey says. "But, if it can be put inside a protective coating, it can be safely used in probes and drug-delivery systems. Electron microscopy can help us determine just how the materials actually interact at the atomic level."
The College's electron microscopes are being used for more than research. When a new instrument is added to the lab, an earlier generation is kept as a teaching tool.
The most significant recent instructional advance was the addition of optional remote-control capability to the two newest instruments (one TEM and the other SEM), which gives faculty members the ability to demonstrate electron microscopy to groups of students in the classroom. "It's not practical to have large groups in the lab, but it is practical to project images from the lab to the classroom," Buttrey says.
With the remote control, an extremely fast Internet 2 connection enables the microscope to be operated from the Engineering Computer-aided Active Learning Classroom, known as eCALC, where 26 workstations allow students and instructors to work in teams. The electron microscope can be demonstrated in eCALC, so that several students learn to use the equipment at the same time. The same web-based feature permits researchers to collaborate with colleagues at other locations.
In addition, the educational use of the College's electron microscopes extends beyond the University, with outreach to students in middle and high schools. Buttrey has developed a set of easy-to-understand presentation and demonstration materials to show kids what can be done with these high-tech tools and to get them excited about math and science. He says he is especially interested in reaching teachers.
"If we talk to a group of 50 children, we've reached 50 children," he says. "But, if we can talk to 50 teachers, we can reach 50 times as many youngsters, and they're the University students of the future."
More information about the electron microscope lab is available on the web at [http://www.che.udel.edu/REQKeckFclty.jsp].