Berkeley Engineering Home
Volume 2, Issue 2
Feb/March 2002

Outline List

In This Issue
Organic Transistors and the Death of the Bar Code

A Digital Doctor on Your Wrist

The Art of Engineering, The Engineering of Art

From Russia With Love: Isotopes and the Future of Semiconductors

Berkeley Engineering History: Howard Grant Graduates




Lab Notes, Research from the College of Engineering

A Digital Doctor On Your Wrist

Prof. Budinger with ultrasound machine David Pescovitz photo

Professor Thomas F. Budinger checks his pulse with an ultrasound machine. His heartrate speeds up when he's fishing for Trophy Brown Trout on the rivers of New Zealand. (Click for larger image.)

Tomorrow's wristwatches may tell you much more than the time. Department of Bioengineering chair Thomas F. Budinger is developing a wrist-worn biomonitoring alert system that will not only transmit a digital call for help if you've fallen but also detect when it's time for a nap or if your "last meal was cooked in old fat, like a fast food hamburger."

As part of the medical alert research component of the Center for Information Technology Research in the Interest of Society (CITRIS), Budinger and his colleagues are hoping their biomonitoring system could save some of the 300,000 lives lost each year from cardiac arrest in this country while bringing peace of mind to those who worry about their loved ones suffering heart attacks, strokes, or dangerous falls while home alone.

"Many people worry about loved ones who are at risk," says Budinger, who is also a senior scientist and head of the Center for Functional Imaging at Lawrence Berkeley National Laboratory and a professor in the Department of Electrical Engineering and Computer Sciences. "If your grandmother has a device, falls down, and doesn't hit the reset button, you want to know about it. So you and all her relatives are served by this kind of system."

Wristwatches containing tiny accelerometers, devices that measure direction and speed of motion, have already been developed by Precision Control Design Inc. (PCD), a private sector collaborator on the Berkeley research.

One of the Berkeley team's tasks is to characterize the accelerometer signature of a person falling as compared, for example, to plopping down in an easy chair. The next step is to outfit the watch with a wireless transceiver to signal an emergency response network in the event of trouble. Budinger is also exploring ways to link the radio transceiver with local area networks and Global Positioning System technology or other automatic location identification systems to precisely pinpoint where help should be dispatched.

"If you have cardiac arrest and you're not resuscitated within six minutes, you can start writing off brain cells in a big way," Budinger says.

Budinger's pet project, however, is to bring an unprecedented level of sensitivity to a wristwatch biomonitor. While a traditional electrocardiogram (EKG) measures the electrical activity of the heart, Budinger believes that studying the actual pressure waveform of blood flowing through the body reveals much more about an individual's physiological state.

"Let's say the accelerometer detects that the person has fallen and is not moving," he says. "Looking at the waveform of their pulse pressure could tell you if the person has a heart beat and possibly is entering a state of shock.

Imagine that the heart is a water balloon and the rest of the cardiovascular system is another water balloon, Budinger explains. Squeezing the "heart balloon" causes the other balloon to expand with liquid. When the pressure on the heart balloon is reduced, the viscoelastic energy is put back into the fluid. The return of the fluid to the heart balloon creates a second pulse.

"That's how your coronaries fill," says Budinger, who is conducting the waveform research with LBNL colleague Jonathan Maltz. "And certain drugs and fatty meals stiffen the system," altering its compliance and the resulting pulse pressure waveform.

Concurrent with designing a wearable system to track the pulse waveform, Budinger is learning the physiological language of waveform variations. The aim, he says, is to translate what specific variations in a waveform signify about someone's health status and their daily physical activity.

"The underlying human physiology of all of this is our current area of investigation," Budinger says.

Once Budinger's insights into pulse waveforms are proven out, the multiple elements of the biomonitoring system can further be integrated to divulge even more details about the wearer's physiological state. Basic activity monitoring technology has already been incorporated in commercial wristwatch devices called actigraphs, including those manufactured by PCD and sold by companies like Ambulatory Monitoring Inc. to help evaluate sleep disorders. By adding pulse waveform and heartrate data and measurements of the wearer's alertness throughout a "personalization period," the wristwatch could become a "human gas gauge." This kind of device, Budinger says, is of great current need by patients undergoing chemotherapy or rehabilitation away from the hospital.

An advanced biomonitor could eventually also be used in crisis situations like those of September 11, he adds, to keep tabs on emergency workers' vital signs and level of fatigue.

"By tuning the device to the individual, the watch could tell you how much fuel is left in your tank," he says.


Thomas F. Budinger's home page

Department of Bioengineering

Lab Notes is published online by the Public Affairs Office of the UC Berkeley College of Engineering. The Lab Notes mission is to illuminate groundbreaking research underway today at the College of Engineering that will dramatically change our lives tomorrow.

Lab Notes is written by David Pescovitz.
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