Taking wireless to a new level, Alyssa Apsel seeks to build integrated system of tiny radios

Think "microchip" and what comes to mind? A computer, perhaps a cell phone or maybe an iPod. But Alyssa Apsel likes to remind people that microchips, or integrated circuits, pervade nearly every aspect of life -- not just the ones most obvious to most people.

"Everything has a chip in it," says Apsel, Cornell associate professor of electrical and computer engineering. "Everything. It's not just the things you think of. It's your coffee maker, toaster, watch, car, thermostat -- everything."

Apsel's lab at Cornell designs circuits for electronic devices, which are getting smaller, faster and more efficient by the minute. She envisions next-generation circuits to have shrunk to the most infinitesimal of length scales, but with higher efficiency and more predictable properties. Mainly, her lab deals with mixed-signal electronics, or those with both analog and digital properties.

Currently, one of her lab's projects is building a network of radios, tinier than any the world has seen, in which each radio consumes 1,000 times less power than today's radios.

Through this network, a user would be able to transmit a signal between several radios, not just one transmitter and one receiver, as is the standard today. The radios would be so small -- millimeters by millimeters -- that they could fit on a sticker, and so efficient that their power supplies would never need recharging.

A system like this could be applied to health-care monitoring; for example, in an EKG machine. Patients now need to be wired to an EKG machine with patches that monitor signals from the heart and send them to a central location.

"Perhaps if you were able to put these radios on the patches themselves, and they'd be very, very small, someone could walk around the environment, and these patches could communicate to each other and also perhaps to a central node," Apsel explained.

Apsel, who teaches a graduate-level course in data conversion and previously taught an analog circuit design course, notes that her research field is still dominated by men. She surmises that may be due, in part, to circuits-based courses being taught in ways that might be unappealing to women. She was fortunate to have a professor at Swarthmore College -- who happened to be female -- and whose enthusiasm for the subject got Apsel hooked on circuits.

"I think the things women are good at are actually fairly well suited to analog circuit design," Apsel said.

Circuits are extremely complicated things that don't always operate in a "nice, well-behaved way," she said. They have all kinds of strange behaviors, but in the end, a designer can either break those devices down to functional blocks or see the system as a "whole intermingled thing."

As a result, there is a lot about circuit design that Apsel sees as intuitive -- even creative.

"It's not just math," she said. "I think if you look at circuits as a mathematical problem alone, you will inevitably never be able to design circuits well. And I think that's a misunderstanding a lot of people have."

It's best to begin to understand how fields and charges interact with each other within a system, and to systematically eliminate pieces that are not needed; simplicity and elegance are key.

"That's the hardest thing to teach," she said.

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