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Miniaturizing Monitoring Equipment Using MEMS Sensor
Omron provides solution for Magee Scientific's Handheld Aethalometer®
Design News Staff -- Design News, October 13, 2009
The Aethalometer®, manufactured by Magee Scientific of Berkeley, CA, is an instrument that uses optical analysis to determine the mass concentration of "Black Carbon" particles collected from an air stream passing through a filter. In the past, these rack-mounted instruments were large and bulky. Magee's AE42 measures 11 × 12 × 8 inch. They collect data from installations located around the world, but these only give scientists limited, local samplings. To further complete the picture, scientists require a very small portable Aethalometer. A significant reduction in size required some clever engineering and component sourcing. One of the major size reduction obstacles to overcome was finding a small, lightweight, highly accurate flow sensor with low power consumption.
SIZE & POWER RESTRAINTS: The body of the D6F-P measures just 10 mm (0.40 inch) high × 23.3 mm (0.91 inch) wide × 27.2 mm (1.07 inch) deep, and with a weight of just 8.4 gm, it fell within the size and weight restraints set forth by Magee. Designed with ease of installation in mind, Omron developed the D6F-P with both the input and output ports on the same side to facilitate the connection of tubing. Magee engineers studied the device and cleverly designed the AE51 with these ports mating directly to their manifold without the need for tubing. Since the new miniature device was to be battery-powered, current consumption was a concern. Drawing just 15 mA maximum while operating on 5V dc, the D6F-P once again proved to be a very efficient device.
ACCURACY & REPEATABILITY: Since the AE51 relies on calculating the exact amount of air for a given time, the flow sensor would have to be very accurate. The D6F-P has a flow range/pressure range of +1.0SLM (+0.84 H20), with an accuracy of ±5 percent F.S. maximum and ±2 percent F.S. typical. This performance would deliver Magee the precise flow readings they required to obtain reliable measurements. Additionally, since the D6F-P's are individually pre-calibrated at the factory for high repeatability, Magee Scientific's finished device calibration time was kept to a minimum.
MAGEE SCIENTIFIC'S REACTION: "Omron's D6F-P was instrumental in the development of the AE51. This technology enabled us to meet our goals in developing this micro-product," says Dr. Tony Hansen, president of Magee Scientific. This Aethalometer is so small that it can be strapped on the user's belt, freeing them up to do other work. It can also be tethered to weather balloons allowing for upper atmosphere readings. The D6F-P is one of a complete line of MEMS flow sensors offered by Omron.
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Miniaturizing Monitoring Equipment Using MEMS Sensor
