Case Study

Optics And MEMS Combine For Unique Accelerometer

Suzanne Finch, Director,

Public Relations and Marketing

Center for Commercialization of Advanced Technology (CCAT) Program, San Diego State University, 5250 Campanile Dr., San Diego, CA 92182-1933; (619) 594-7221, e-mail: sfinch@foun-dation.sdsu.edu, Internet: www.ccatsandiego.org.

MICROELECTRICAL-MECHANICAL-SYSTEMS

(MEMS) technology may be best known for the millions of chips used in millions of airbag systems in commercial vehicles. But the technology has broad capabilities for such applications as signal routing, antenna switching, and phased-array systems. And the engineers with the United States Navy and the Space and Naval Warfare Systems Center ( SPAR-WAR, www.spawar.navy.mil) have found a way to combine MEMS and electro-optical technologies to form one of the world’s most unique and sensitive accelerometers. Part 1 of this Case Study will explore the roots of this innovative MEMS/optical sensor technology and how the Center for Commercialization of Advanced Technology (CCAT) Program helped start a company to bring the technology to market.

One of the developers of the new accelerometer technology, Dr. Richard Waters, started working at SPAWAR in 1999, already familiar with accelerometers based on MEMS technology. Although MEMS

accelerometers can accurately measure acceleration in navigational vehicles, and can also be used for measurements of other types of movements, including vibration and velocity, Waters knew the technology was costly and these types of accelerometers were still too expensive for most applications. From his work as a scientist and his academic studies, he was able to envision an accelerometer based on Fabry-Perot interferometer technology that could offer equal or greater performance at a lower cost.

A Fabry-Perot interferometer, which filters specific optical wavelengths, is typically found in wave-length-division-multiplex (WDM) optical communications systems where it serves to separate differ-ent-wavelength channels, although not commonly built into an accelerometer. Still, Waters envisioned the possibilities of combining the two technologies, proposing that a device with both technologies could be fabricated with proven microelectronic processes employed by the semiconductor integrat-ed-circuit (IC) industry in order to lower costs for volume production while also achieving the dimensional tolerances required by MEMS devices.

Waters secured internal funding from SPAWAR in 2000 to fund a proof-of-concept project. By 2001, he had built several working devices that could demonstrate his concept. As Waters had theorized, it was

possible to deliver a working, accurate MEMS accelerometer using Fabry-Perot interferometer technology.

While proving the technology was a surprise, the bigger surprise was that the performance was far better than anyone had anticipated. As Brad Chisum, formerly of SPAWAR, recalls: “In fact, it was a device that achieved world-record sensitivity right out of the box.” Chisum met Waters in March of 2003 while both were working at SPAWAR. Waters was working on the device design team and Chisum was working on the project’s manufacturing team. “It intrigued me from the beginning because it this was the first time I’d seen something completely different from what I’d been exposed to,” says Chisum. “It wasn’t the extra button on a cell phone, it was a completely brand new concept and the versatility of its applications.”

Next month, this two-part Case Study will conclude with details on the founding of Omega Sensors and how the fledgling technology company was aided by financial support from San Diego’s Center for Commercialization of Advanced Technology (CCAT) Program.

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