Engineers shrink microscope to dime-sized device
This is dramatically shrinking the size—and, hopefully, the price tag—of a high-tech device commonly used to characterize material properties.
"A standard atomic force microscope is a large, bulky instrument, with multiple control loops, electronics and amplifiers," said Dr. Reza Moheimani, professor of mechanical engineering at UT Dallas. "We have managed to miniaturize all of the electromechanical components down onto a single small chip."
Moheimani and his colleagues describe their prototype device in this month's issue of the IEEE Journal of Microelectromechanical Systems.
An atomic force microscope (AFM) is a scientific tool that is used to create detailed three-dimensional images of the surfaces of materials, down to the nanometer scale—that's roughly on the scale of individual molecules.
The basic AFM design consists of a tiny cantilever, or arm, that has a sharp tip attached to one end.
As the apparatus scans back and forth across the surface of a sample, or the sample moves under it, the interactive forces between the sample and the tip cause the cantilever to move up and down as the tip follows the contours of the surface. Those movements are then translated into an image.
"An AFM is a microscope that 'sees' a surface kind of the way a visually impaired person might, by touching.
You can get a resolution that is well beyond what an optical microscope can achieve," said Moheimani, who holds the James Von Ehr Distinguished Chair in Science and Technology in the Erik Jonsson School of Engineering and Computer Science. "It can capture features that are very, very small."
The UT Dallas team created its prototype on-chip AFM using a microelectromechanical systems (MEMS) approach.
"A classic example of MEMS technology are the accelerometers and gyroscopes found in smartphones," said Dr. Anthony Fowler, a research scientist in Moheimani's Laboratory for Dynamics and Control of Nanosystems and one of the article's co-authors.
"These used to be big, expensive, mechanical devices, but using MEMS technology, accelerometers have shrunk down onto a single chip, which can be manufactured for just a few dollars apiece."
The MEMS-based AFM is about 1 square centimeter in size, or a little smaller than a dime.
It is attached to a small printed circuit board, about half the size of a credit card, which contains circuitry, sensors and other miniaturized components that control the movement and other aspects of the device. ■
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