UCLA design could power MEMS

Advanced Battery Technology, Apr 2003

Bruce Dunn, a materials science professor from the UCLA Henry Samueli School of Engineering and Applied Science, believes a radical new design for a lightweight, rechargeable battery - a design based on three-dimensional geometry - will provide power to a host of microelectromechanical systems, or MEMS, so small that traditional batteries cannot be used. They would have to fit inside devices smaller than the width of a human hair and still provide long-lasting power.

The UCLA-led team proposes changing from two-dimensional sheets of electrodes to rods arranged in a three-- dimensional array in which hundreds of rods are stacked next to each other like tubes on a flat-bed truck. Each rod is only a thousandth of a centimeter in size.

This design keeps the battery compact and provides a short travel distance for the ions. "A more efficient path for the movement of ions means less power loss and a longer-- lasting battery," Dunn says.

The group is currently designing a battery five millimeters in size, which presents significant design challenges. "We're going to use fairly well-known lithium battery materials," Dunn says. "The hard part is fabricating it into a structure."

UCLA professor C.J. Kim, from the department of mechanical and aerospace engineering, is an expert in micromachining techniques. He and his students are creating silicon chips to be used as molds. The electrode materials are placed in the molds, left to harden, and finally the silicon mold is etched away, leaving behind the three-dimensional battery electrode structure.

Batteries this small are necessary to run MEMS device,, used in the medical, automotive, and aerospace industries, i.e.. doctors could use implantable devices that deliver drugs or protect transplanted cells. Other devices could be used to automate blood, tissue and cellular analysis at much lower costs than conventional techniques.

This five-year collaborative effort is funded by a $4 million grant from the Office of Naval Research and includes researchers from the University of Florida, the University of Utah, and other UCLA faculty members, including chemistry professors Fred Wudl and Sarah Tolbert.

Visit www.uclanews.ucla.edu.