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'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
"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
Department of Bioengineering