UCLA to develop rotating MEMS | Microtech Ventures

by R. Colin Johnson
Contributing Editor, MEMS Investor Journal

Newcomers usually expect that MEMS devices like gyroscopes have internal rotating gymbals similar to their life-sized counterparts. Unfortunately, so far no commercial MEMS chips employ moving parts that are not tethered. Now researchers at the University of California at Los Angeles (UCLA) have received a four-and-a-half-year $5.5 million award from the Defense Advanced Research Projects Agency (DARPA) to get past this obstacle.

"One of the challenges we are facing is that you can't have electrical wires protruding from an object that rotates endlessly," said UCLA professor Chang-Jin Kim. Kim, who is principal investigator on the DARPA project, is performing the work with fellow UCLA professors Ken Yang, Eric Chiou, Sungtaek Ju, Jason Woo and an engineer at MEMS maker Innovative Micro Technology (IMT), Chris Gudeman.

The micron-scale, freely rotating, yet electrically connected devices will be used for sensing and communications in DARPA's Information Tethered Micro Automated Rotary Stages program (ITMARS). The goal of ITMARS is to fabricate a MEMS device that can freely rotate while being electrically connected to both signal and power sources. The device will be used for position-measuring instruments that achieve superior accuracies compared to those obtained today by non-MEMS optical rotary stages.

UCLA was awarded the grant because of its previous successful fabrication of a five-millimeter-sized rotary stage using metallic liquid droplets as the "ball bearings" which provided both lubrication and physical support. So far, however, the researchers have not yet attained precise control of the rotating device with electrical signals. Thus, the team’s first goal is to electrostatically drive the device with nearby electrodes whose synchronized signals are timed to precisely rotate the part into any desired position.

The electrical driving circuitry to control the position of the rotor will be located on an integrated circuit that is located below the MEMS device. Capacitive sensors will track the position of the rotor as it turns under control of the electrostatic drivers. Once the concept is proven, the rest of the program will be spent to optimize the device for precision, size and low-power operation.