Researchers in Toronto and Waterloo, Ont., are working on a way of using micro-electromechanical systems (MEMS) in a device that could help detect and treat cancer more effectively by scanning the human body.
Toronto’s Princess Margaret Hospital, part of the University Health Network associated with the University of Toronto, is working on the Endoscopic Coherent Optical Microscope (ECOM), which would use a technique called optical coherence tomography (OCT). Optical coherence tomography uses a directed beam of light to scan body tissue. Dr. Alex Vitkin, a member of the ECOM team and an associate professor in the University of Toronto’s Department of Medical Biophysics, explained that this can be an alternative to performing a biopsy, which means removing a small section of tissue and analysing it in a laboratory.
Using OCT instead of a biopsy is not only cheaper and more convenient, Dr. Vitkin says, but is an option in some cases where a biopsy is not possible.
One of the challenges facing the ECOM team, though, was building a device to direct the beam of light that would be tiny enough to be used inside the body. OCT can be used in the intestines and potentially even in blood vessels. An optical fibre carries the light to the area to be scanned, but there must be a way of directing the beam. This device is called an endoscope, and those available today are about a centimeter in diameter — too big for many potential uses.
Enter Dr. John Yeow. As a graduate student researching MEMS at the University of Toronto, Dr. Yeow heard about the problem from another graduate student over coffee about four years ago. He set to work on applying MEMS to creating a smaller endoscope.
Micro-electromechanical systems are made the same way as silicon chips — by depositing layers of material on a silicon substrate — but they have microscopic moving parts. Dr. Yeow’s device includes a tiny mirror — about 1.4 by 1.7 millimetres — which is controlled by the electronics on the device. The entire unit, when completed, will be less than half a centimeter in diameter, he said.
Yeow — who is now at the University of Waterloo — used software called MEMS Pro, developed by a North Carolina company called MEMScap Inc. and provided through the Canadian Microelectronics Corp., a government- and industry-backed body based in Kingston, Ont., that supports microsystems research across the country. CMC also arranged for the prototype design to be produced at a fabrication facility at Cornell University in Ithaca, N.Y.
CMC supports researchers by supplying them with state-of-the-art technology and acting as a broker with fabrication facilities to help get designs produced, explained Sonya Shorey, CMC’s manager of communications. In some cases CMC can reduce fabrication costs by arranging for several researchers’ designs to be produced as part of a single silicon wafer. The organization does not provide researchers with direct funding — the ECOM project is supported by the Natural Sciences and Engineering Research Council, the Canadian Institutes for Health Research and other government funding bodies.
Having built a prototype, the researchers now have to package and optimize the technology, Dr. Yeow said. Within two years they hope to test it on laboratory animals at Princess Margaret and Saint Michael’s Hospital in Toronto, and after that will come human trials — probably in about four years, Yeow said.
Vitkin said the ECOM could improve cancer diagnosis by scanning larger areas of tissue than can be tested in a biopsy, reducing the chances of missing malignant tissue. Dr. Yeow added that the device will be “”minimally invasive,”” causing less stress and discomfort for patients.
MEMS research has been going on since the 1960s, with the first commercial applications appearing around 1990, and MEMS devices are used in such areas as vehicle emission systems, computer printers and medical applications. Research firm InStat/MDR of Phoenix, Ariz., has projected sales of MEMS devices will grow to about US$9.6 billion by 2006.
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