The flow sensor is made up of a heater that raises the temperature of the fluid at one point in the flow stream. Two heat sensors downstream detect this hot spot as it passes by. From this measurement the flow rate can be calculated.
The device has been bench tested successfully and is being scaled down for mass production, Huff reported at SPIEs Smart Structures and Materials Symposium in San Diego earlier this month.
The field of microelectromechanical systems and micro fabrication research has led to the development of micro devices which have feature sizes down to a micrometer or less. The field, which developed from integrated circuit fabrication techniques, has recently expanded into the medical device market.
"No company wants to build hospital infusion pumps any longer, since the whole health care system is striving to keep people out of hospitals," Huff said. "Drug delivery systems should be based on ambulatory delivery."
Medical care has already begun to feel the influence of microelectromechanical systems. Ten-dollar disposable blood pressure instruments with microscopic pressure sensors are replacing conventional $600 devices that, while reusable, cost another $50 to sterilize and tune up before each use.
About 20 million miniature blood pressure sensors are now being used each year, in addition to other downsized pumps and sensors. But there are still no closed-loop systems on the market that can regulate themselves without a doctors intervention.
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Contact: Frank Blanchard
fb@whitaker.org
703-528-2430
Whitaker Foundation
20-Mar-1997