Maximizing MEMs

To get the most of their MEM sensors, one manufacturer turned to Ideal Aerosmith to overcome the effects of temperature instability and harmful acoustic noise during calibration.

How we solved it.

the challenge

By nature, MEM sensors are, well, sensitive. That’s their job. Unfortunately, this can also make testing a rather complex process. A prominent manufacturer of navigation sensors asked the team at Ideal Aerosmith to help with the challenge. There were two main hurdles to overcome: First, the MEMs needed to be tested in an environment that had very little acoustic noise. This was a problem because liquid nitrogen (LN2) was needed to keep the process at a uniformly cool temperature, and the nozzle from which it was expelled produced a noise that exceeded the limits of the testing environment. The second problem was just as vexing, as the large quantity of LN2 entering the chamber in one location would cause a cold spot that required time to circulate evenly throughout the chamber. The resulting inconsistencies in temperature throughout the chamber would make tests unreliable.

In fact, locating a single LN2 injector was problematic in and of itself. The liquid tended to reach the table before it had time to dissipate into gas, causing problems as it came in contact with either the table top or other components. In addition, as the table’s outer axis rotated, the LN2 spray would be directed at different angles. This resulted in variations in cooling performance depending on the orientation of the chamber and table.

“We needed a quieter, more uniform way to inject the liquid nitrogen,” says Gary Kleven, director of engineering at Ideal Aerosmith. “We needed to create an environment that would result in more accurate test results.”

the solution

The Ideal Aerosmith engineering team didn’t overcome this challenge with a single solution. Just the opposite. The right answer was to disperse the LN2 with sixteen nozzles instead of one. “Rather than wrestling with a single nozzle on the centerline of the horizontal axis, we created a customized system with sixteen nozzles mounted around the roof of the chamber,” Kleven says. “It delivered the liquid nitrogen much more effectively.”

By injecting smaller quantities of LN2 directly into the airstream of the testing chamber’s fans, the system improved atomization of the liquid, eliminated pooling and significantly reduced unwanted hot and cold spots in the testing environment. At the same time, multiple smaller nozzles operate much more quietly than one large one.

the outcome

“More and more manufacturers are working to calibrate their MEM sensors to obtain better performance, and that requires carefully controlled temperatures and very low acoustic noise,” Kleven explains. “By creating a more reliable testing environment, we helped our customer to achieve their testing goals.”

That, in turn, will help the MEM manufacturer to reach their business goals. The successful project not only helped Ideal Aerosmith’s customer to overcome a hurdle in their production process, it ensured that manufacturing could be undertaken with confidence. That’s the power of great testing, and the advantage of choosing Ideal Aerosmith.

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