- BY Dan McGraw  

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 nature—from 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 of BMES.

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, and legs.

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 research.”

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 brain—transmitted through the microelectrodes—to 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, Texas.
He can be reached at dmcgraw@asee.org.