"One of the real difficulties in diagnosing illness is looking at an image and having it tell you something meaningful about what's going on with injured or sick cells," he said. "But if you could see that a cell was producing the wrong kind of protein based on the change in electrical resistance, you could more easily determine what was going wrong in a patient's body. Once you understand how things work, it's much easier to combat or fix things that are wrong."

Hawkins, Oliphant and Stephen Schultz, also on the engineering faculty, developed the prototype, which is described in "Applied Physics Letters." They wrote the paper, along with Hongze Liu, a graduate student. The project involved a team of undergraduate engineering students, as well.

Because they're seeing things that can't otherwise be observed, they don't know what it will ultimately mean. They expect that it could open many doors in biology and medicine for research and discovery.

A professor of biophysics at the Mayo Clinic College of Medicine, James P. Greenleaf, called it a "very important and novel method of imaging" and said it provides information that usually can't be imaged.

To create an image with the prototype, engineers put a sample on a flat aluminum-coated silicone wafer that sits in a container filled with water. A tiny probe goes in right above the sample and moves across it like a scanner attached to a computer, but this probe takes voltage measurements. Since electrical current is resisted differently by different things, it creates an image of light and dark hues. Cancer shows up much darker than healthy tissue.

A new generation of both the instrument and the probe are being created even as this one is being introduced.

---

E-mail: lois@desnews.com