Super-accurate sensors for fighting crime, medical devices, and environmental testing

Purdue researchers have developed the first self-calibrating MEMS. These super accurate sensors or actuators could be used to fight crime and improve medical devices.
Written by Boonsri Dickinson, Contributing Editor

You might not know what MEMS technology is, but we've all used it. Our gadgets have these micro electromechanical systems embedded in them.

Inside each Nintendo Wii video game, iPhone, or airbag there is some kind of systems-on-a-chip that makes it tick. The chip is made from silicon substrate (using microfabrication) and has integrated mechanical elements, sensors, actuators, and electronics parts. Fortunately to work in these commercial applications, the MEMS technology doesn't need to be that accurate.

But it's really hard for the sensor to measure small forces, which can limit its wide-spread use in other high tech areas.

Purdue researchers discovered a way to measure these incredibly small forces using a new technique called electro micro metrology, or EMM for short. The idea is to have these sensors self-calibrate.

"For the first time, MEMS can now truly self-calibrate without any external references," Jason Clark, a Purdue engineering professor, said in a statement.

"That is, our MEMS are able to determine their unique mechanical performance properties. And in doing so, they become very accurate sensors or actuators," he said.

This nose-on-a-chip could help sniff out criminal activity, improve medical devices, and detect environmental contaminants.

I know from personal experience how difficult these MEMS are to work with. When I was an undergraduate at the University of Florida, I was working with a graduate student who was making a lab-on-a-chip (a type of MEMS) for my senior project. I think I waited an eternity for him to make the "perfect" MEMS.

It took me some time to realize that the device would never be perfect.

Unfortunately, perfection matters. Any little variation in the width of the channel could influence how stiff the structure actually is, which can directly affect its performance.

Just "a 10 percent change in width can cause a 100 percent change in the microstructure's stiffness," Clark said.

MEMS are really sensitive. If the sensors could measure really small forces, scientists would know more about things like van der Waals forces and have a way to manipulate data storage and control nanoassembly.

Indeed, self-calibration is critical. In situations when the temperature or air conditions change, the MEMS sensors need to be able to take accurate measurements and reset themselves accordingly.

That said, Clark is now creating an atomic force microscope-on-a-chip that could make the device smaller and cheaper. In a way, the AFM has revolutionized nanotechnology.

But that was just a start. Imagine what this self-calibrating MEMS could do.

Photo: Jason Vaughn Clark, Purdue University Birck Nanotechnology Center

This post was originally published on Smartplanet.com

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