Bioengineers are developing microelectronic devices
that could lead to
amazing medical breakthroughs, including rudimentary sight recognition
for the blind and, for the paralyzed, the ability to reach and grab.
WHEN C.L. MAX NIKIAS, dean of the University of Southern California
(USC) college of engineering, speaks of the prospects of implantable
microelectronic devices to help alleviate human suffering and treat
incurable diseases, he sounds almost biblical. Our very ambitious
goal is to help the blind see, the paralyzed walk, and to restore the
function of memory, Nikias says.
The technology behind these devices is still in its infancy. The steps
being taken now are within the realm of preventing muscle atrophy through
electrical stimulation, and regenerating tissue damaged by disease.
And despite Nikias's hope, no one is predicting that paraplegics
will have full use of their muscles any time soon.
But the prospect of great medical breakthroughs from this bioengineering
research is more than just wishful thinking. So real are the prospects
that the National Science Foundation recently awarded a five-year, $17
million grant to fund the new Biomimetic MicroElectronic Systems (BMES)
Engineering Research Center at USC. The center will be a collaborative
effort among USC, The California Institute of Technology, and the University
of California-Santa Cruz (UCSC).
The desire to alleviate the worst in human suffering has always been
of paramount importance to scientists in the engineering and medical
community. Work in the past has been primarily auxiliary in naturefrom
high-tech wheelchairs and breathing aids for paraplegics to chirping
traffic signals to help the blind cross the street safely. The BMES
project will undertake research that might eventually lead to a better
understanding of how the brain and physical tissue work together, and
perhaps lead to cures for currently incurable maladies.
The BMES project is very much a collaborative effort, combining the
skills of biomedical engineers, electrical engineers, and research physicians.
For engineering students at the three schools, the prospect of hands-on
biomedical engineering research in the groundbreaking project is exciting.
What we are going to have in the research project is the ability
for students to come and see patients, says Mark Humayun, professor
of ophthalmology, biomedical engineering, and cell and neurobiology
at USC, and the director of BMES. My focus in teaching in this
field is to tell students, solve this human suffering.' We
want students to see how blind people suffer and get through life; we
want them to see the real consequences of a person confined to a wheelchair.
This is a powerful motivator for students. That's what drives innovation.
That's what drives medical breakthroughs. Researchers like
Humayun, who has a background in medicine and engineering, are the backbone
Though helping the blind see and the lame walk are long-term goals,
the research during the next five years will concentrate on three test-bed
projects: a retinal prosthesis that could reverse cell degeneration
caused by eye diseases; an injectable microelectronic stimulator to
aid stroke victims; and a cortical silicon chip prosthesis to take over
the function of neurons lost to disease or injury.
Gerald Loeb, a professor of biomedical engineering at USC, has been
working on a microelectronic device called a BION, short for bionic
neuron. BIONs are tiny glass capsules about the size of a grain of rice,
implantable within tissue with a 12-gauge needle, and activated by a
radio signal through inductive coupling from a coil worn by the patient.
BIONs produce an electrical stimulus that is capable of 3,000 different
commands per second.
The initial research centers on using electrical stimulation from BIONs
to rebuild the strength in the muscles of stroke victims. Eventually,
researchers would like to use BIONs to help paraplegics walk. About
the last thing that will be done with this technology is the possibility
of making paraplegics walk, says Loeb. People in wheelchairs
face many life-threatening complications, things like pressure sores,
deep vein clots, pneumonia from not being able to cough properly, and
bowel and bladder function.
Loeb believes the alleviation of these life-threatening symptoms through
the electrical stimulation of the afflicted tissues is the best prospect
for the first generation of BION research. Researchers hope that future
generations of BIONs will restore function to paralyzed hands, arms,
USC biomedical engineer Rahman Davoodi is studying computer simulations
of moving human limbs. The research might lead to an understanding of
how much electrical stimulation of a muscle or a nerve is needed to
make a hand grip or a leg stand.
SIGHT TO THE BLIND
THE RESEARCH INTO a retinal prosthesis for people who have lost sight
to disease involves an implantable microelectronic device that stimulates
the inner-layer neurons of the retina. The patients wear a pair of high-tech
glasses that receive, code, and transmit images over a wireless connection
to the implant. Electrical power is also supplied to the microelectronic
implant through this connection.
Wentai Liu, a professor of engineering at UCSC, says that early clinical
trials have been promising, allowing some patients to follow light and
recognize some objects. The major problem in designing the 5 mm by 5
mm retinal implant has been trying to manage the heat it will generate.
The eye is extremely sensitive to heat. Liu says a temperature rise
of even one degree can damage tissue in the eye.
We have to be very careful of the issue of heat, Liu says.
The eye has such a limited space, so the size of this has to be
very small, and the heat generated has to be managed. But we are learning
many things through the research, especially about the interface technology
that allows the microelectronics to receive data and power from a remote
source, and the ability to interact with living tissue.
The researchers all caution that the microelectronic technology being
studied within the BMES project might only work with patients who once
had movement in limbs or could see but have lost those abilities to
accident or illness. The promise of using these tiny devices, however,
combined with research into the brain activity that controls such basic
human neuromuscular functions, is fostering genuine optimism.
We can now do some crude movement through external electrical
stimulation of muscles that have been damaged by spinal cord injuries,
says Patrick Jacobs, an expert in exercise physiology with the Miami
Project, a nonprofit research group founded by NFL Hall of Fame linebacker
Nick Buoniconti, after his son, Marc, suffered a spinal cord injury
in a college football game. The microelectronic approach using
the BION is a very interesting approach, and we see it as very exciting
The ideal way to reverse these injuries would be to interface the microelectronic
implants with the patient's brain activity. Though such a solution
is not now visible on the horizon, there is some promising research
in that direction. Research at Duke University, led by Miguel Nicolesis,
a professor of neurobiology and co-director of the Duke Center for Neuroengineering,
found that monkeys could control robotic arms using signals from their
brains and visual feedback on a video screen.
In the experiments, the Duke team implanted an array of microelectrodes,
each smaller than a human hair, into the frontal and parietal lobes
of the brains of two female rhesus monkeys. They were first taught to
use a joystick to move the robotic arm, but eventually learned to use
signals from their braintransmitted through the microelectrodesto
move the robotic arm without the joystick.
There is certainly a great deal of science and engineering to
be done to develop this technology and to create systems that can be
used safely in humans, Nicolesis said in a recent interview. However,
the results so far lead us to believe that these brain-machine interfaces
hold enormous promise to restore function to paralyzed people.
Like all medical research, the work being done to make the blind
see, and the paralyzed walk will come in phases. The first phase
will involve alleviating some of the debilitating medical problems,
and eventually may lead to rudimentary sight recognition or the ability
to use electrical stimulation to reach and grab. Later, maybe decades
in the future, will come the technology to create an interface between
patients' undamaged brains and their damaged physical tissue.
There will no doubt be spin-off technology through the BMES research
into these microelectronic devices, and there will be many business
opportunities for biomedical companies that can bring these breakthroughs
to the medical marketplace. But the real excitement of the project,
according to Steve Kang, dean of the Baskin School of Engineering at
UCSC, will be the educational breakthroughs for students, as well as
patients. We will be doing educational outreach in this research,
from undergrads to kids in elementary school, Kang says. We
want to impart upon these students the real excitement that comes when
technology impacts human health. There is nothing more important that
we, as engineering educators, can do than to help our students improve
the human condition.
Dan McGraw is a freelance writer based in Fort Worth,
He can be reached at firstname.lastname@example.org.