Jun 1, 2002
by Anton Zuiker
They are cutting-edge machines smaller than your fingernail. They have become crucial to the safe operation of bigger, complex machines like automobiles and airplanes. They’re known as MEMS, short for microelectromechanical systems. And researchers at the Cleveland Clinic are actively working on ways to use MEMS technology for the most complex machine of all – the human body. Soon, a patient will not only arrive at the Clinic in a vehicle whose efficient operation is made possible by MEMS, when she goes home from the Clinic, she may well have such a device implanted inside her to monitor her recovery.
The pursuit of the small could be the source of big innovations at the Clinic. And Shuvo Roy and Aaron Fleischman are the hospital’s dream team, for their job is just that: dreaming up ways to apply MEMS technology to biomedical needs.
In their labs at the Clinic’s Lerner Research Institute, Roy and Fleischman are working with a vascular surgeon to develop sensors for monitoring the minute pressure changes within an aneurism. An implantable device now in the works will monitor the healing process after a spine fusion. Another effort is seeking ways to fit smart sensors onto surgical instruments, which could then differentiate whether a surgeon is cutting through soft tissue or a blood vessel. Indeed, it is MEMS for surgical tools and implantable devices that Roy and Fleischman expect to have the most impact on hospital patients not just at the Clinic but worldwide.
Roy and Fleischman studied MEMS at Case Western Reserve University, where both earned doctorates in electrical engineering and computer science. As they were finishing their research at CWRU, they each received multiple job offers and were set to part, Roy to the West Coast, Fleischman to the East. But then Fleischman heard back from the the biomedical and engineering department at the Cleveland Clinic, and, honoring his pact with Roy, asked the Clinic to hire his research partner as well. Since late 1998 the two have collaborated at the BioMEMS Laboratory, part of the Clinic’s Lerner Research Institute that annually spends $39 million on various medical research.
“MEMS is cutting-edge technology for the aeronautical and automotive fields,” says Roy. The goal of the BioMEMS team is to bring that technology to medicine. Roy predicts their research and development of MEMS devices will have a global impact within five-to-ten years.
Today’s automobiles are equipped with MEMS accelerometer sensors that react swifty to abrupt deceleration, triggering the inflation of airbags. Sensors near the engine measure pressure and temperature and monitor fuel consumption. Airplanes also rely on MEMS for many functions, from keeping the cabin pressurized to measuring airspeed to detecting ice build-up on the wings. Traditional electronics, and even MEMS made of silicon, wouldn’t last long inside a planes’s gas turbine engines, which can heat to 1500 degrees Centigrade. The research that Roy and Fleischman did at CWRU looked for ways to develop new MEMS from matericals such as silicon carbide that could be deployed inside those engines to monitor their performance and to help ensure correct fuel-to-air ratios by monitoring the chemical mixture of the exhaust, as well as to sound the alarm if any part begins vibrating more than it should..
Roy’S research suggested MEMS technology for “smart” ice-detection systems to warn pilots when an airplane’s wings are beginIng to freeze. His work was also used by NASA in considering ways to keep the space shuttle from icing up in orbit, and Roy helped the agency develop new sensors for its Mars probes as they hurtle through the harsh environment of space. At the Clinic, Roy isn’t working with icy spaceships or hot engines, but the human body isn’t any more welcoming of the tiny systems.
“I made the transition from one harsh environment to a different kind of harsh environment,” says Roy. The body is a much tougher setting to deal with, he says, becausE, unlike automobiles and jet engines, it has an active defense mechanism in its immune system which attempts to kill and destroy interlopers, regardless of whether they’ve been sent to help heal the body (think of the 1968 film The Fantastic Voyage.) Because of that hunt-and-destroy defense, bioMEMS devices must be coated with chemicals, biological material or polymers acceptable to the body. “These are not trivial problems,” says Roy.
In addition to the challenges of coating implantable devices, MEMS developers are also striving to find safe methods of telemetry that can allow a device to send signals to a receiver outside the body. “We need to address them not only because the technology is cool but because it must be safe for the patient.”
The proximity of the Clinic, CWRU and NASA-Glenn Research Center create a unique opportunity for collaboration here, says Roy, and thus give Cleveland a leg up on this kind of research and development. CWRU’s “clean room”, a dust-free and temperature-controlled lab space, is where Roy, Fleischman and other members of the Ohio MEMS-net consortium assemble their devices. A spin-off division of NASA became the Glennan Microsystems Initiative, which, among its goals, aims to develop tools for minimally invasive surgery. While most MEMS technology companies are based on the West Coast, Ohio might be considered the center of the bioMEMS field: Each September, Ohio State University hosts the pioneering BioMEMS and Biomedical Nanotechnology World Conference.
In a paper published last October in the journal Neurosurgery, Roy and Fleischman predicted the transformation of neurosurgery through MEMS technology. Possible uses include intracranial pressure-monitoring systems, spine monitoring systems, and neural prostheses that could control epileptic brain activity. Similarly, says Roy, the deep brain stimulation surgery performed at the Clinic (Live, January 2001) might very well evolve to include an implanted MEMS device to better control the involuntary movements of Parkinson disease.
Healthy persons might meet MEMS, too. Already such small devices are being used in sleep movement studies, where subjects wear “tilt monitors” to record nighttime tosses and turns. Athletes might use these sensors to control their posture, says Roy. “Not all bioMEMS systems have to be implanted,” he adds. MEMS sensors have been built into a sleep vest that can warn parents when a baby susceptible to Sudden Infant Death Syndrome has stopped breathing. A healthy John Glenn, when he returned to space a few years ago, swallowed a bioMEMS pill that, as it worked its way through his gut, monitored the effects of weightlessness on his inner spaces.
Other researchers are applying mathematical models of ants and other animals to bioMEMS. Swarm theories that look at how these creatures, incapable of certain behavior on their own but able, as a community, to operate in ways that clearly show intelligence, might lead to smart devices that can mobilize a microscopic army to surround a tumor and destroy it. Drug-delivery devices could pinpoint areas of the body for drug therapy; one device can already dispense minuscule, but precise, doses of painkillers to treat lower back pain.
“We figure out how to solve problems,” says Roy. The Cleveland Clinic, he says, will never be in the business of selling its MEMS products (a technology transfer office passes on prototypes to start-up companies). “MEMS doesn’t refer to one technology. It’s a way of making things small and smart.” Some of Roy’s creations will be as small as a grain of rice.
A recent Clinic breakthrough, though it didn’t come out of the BioMEMS lab, won national attention earlier this year when Dr. Jay Yadav, an interventional cardiologist, announced the development of a thumbnail-size implantable heart monitor that, once anchored on the heart wall, will relay information about pressure changes in the heart’s chambers to a computer or monitor outside the body by the use of wireless telemetry. Technology that helps a plane engine run smoothly will help diseased hearts maintain optimal performance.
This R&D work isn’t cheap, notes Roy. But once a device has been designed and tested, millions can be manufactured at a relatively inexpensive cost, much like the mass-produced microchips that run our personal computers. The Pittsburgh-based MEMS Industry Group estimates that by 2004, there will be five MEMS devices for every person in the U.S.
And, if Roy and Fleischman are successful in the lab, many of those devices will be in or on Americans quietly monitoring patients’ health as they leave the hospital.
Anton Zuiker ☄
© 2000 Zuiker Chronicles Publishing, LLC