University of Utah scientists have developed a tiny instrument that characterizes the way living cells respond to electricity.

As blood cells pass through the microelectronics device, "we can get electrical information about the cell," says A. Bruno Frazier, assistant professor in the departments of bioengineering and electrical engineering.Minute samplers built by Frazier and his lab crew allow them to make a profile of the cells' responses over a range of electrical frequencies. "Eventually, you get a fingerprint for each type of cell . . . And it turns out, by doing this you can tell differences between cells."

The device can differentiate between a white blood cell and a red blood cell. It can tell if a cell's responses are normal. It can even recognize a cancerous cell.

"We're the only people in the world doing it," he said last week during a tour of research and development labs in the Merrill Engineering Building.

Other miniaturized devices the U.'s bioengineers developed allow the mixing of minute amounts of chemicals, provide inexpensive sampling for pollution control and help map brain activity. Most of the work is funded by industry.

In the laboratory of Room 2490, Frazier showed an instrument that was a shiny square about the size of a dime. He slid it under a microscope so its details could be seen. The microscope's screen glowed with a branching design - tubes, openings and mixing chamber.

Formed as a square, the instrument has five receptacles, or ports, on each side that funnel fluids into a central reaction chamber. The openings are so small you could line up nearly 50 of them to an inch. The device allows mixing 20 different chemicals in the chamber.

"This particular device is on silicon," he said. "Doesn't have to be. We do a lot of work with plastic and glass also."

The device lets researchers analyze the reactions that result when minute quantities of chemicals are mixed, as in creating new drugs.

Ian Papautsky, a graduate student in bioengineering, is working with an array of pipettes, or tubes, that are used to take samples. Instead of openings arranged along the sides of a square, the array looks like a comb for some ridiculously tiny head.

"It's a micro-scale instrument for fluid handling," he said. It can draw in samples of fluid through the pipettes, or take fluid from a larger syringe and then force it out through the pipettes.

"We could load DNA samples into a micro-scale analysis system."

Made of nickel or palladium, the arrays are fabricated in another lab downstairs in Merrill Engineering, using techniques such as etching, photo lithography and metal deposition.

"We've made arrays that vary from five to 10" tubes, Papautsky said. "But we could have as many as 100 of those."

Why scale down instruments?

The smaller a blood sample taken from a patient, the better. Also, Frazier said, some analytical systems are small and their samples must be on the same scale. "Otherwise it floods the system."

Many of the instruments are inexpensive because they are little. When no longer needed they can be thrown out.

Also, in running its analysis, a large system might take 10 to 100 times as long as its mini-counterpart.

One device has hairlike wires trailing off the chip. "They're for interfacing with the brain, mapping the brain," Frazier said.

Scientists can use it to study the brains of laboratory rats, and the animals' brain structure can be correlated to the human model. By stimulating target neurons and observing the reactions, they can draw up precise maps of the brain.

"It has applications to artificial limbs," Frazier said.

When researchers know exactly what parts of the brain control which muscles, they may be able to build an interface that ties a person's brain to a mechanical limb. The prosthesis could move in response to the same commands the brain gives to a living limb.

Someday, Frazier believes, "you can use your brain to control your artificial limb."

Downstairs, in the Hedco Microelectronics Laboratory, students and professors fabricate integrated circuits, sensors and microscopic instruments. Recently, the National Science Foundation awarded a $2 million grant that went toward installing a new "clean room" and microelectronics fabrication gear.

"We have probably $10 million, $20 million worth of equipment here to do our research," he said.