Researchers at Case Western Reserve University have developed a prototype of a miniature fuel cell with a volume of only five cubic millimeters, or the size of a pencil eraser. The new cell was produced using high-tech micro-fabrication techniques.
"The rash of new electronic products on the market over the last dozen years and the rush to further miniaturize these devices has driven the demand for this technology," said Robert Savinell, director of the Ernest B. Yeager Center for Electrochemical Science and associate dean of the Case School of Engineering.
Fuel cells are devices that directly convert the chemical energy in a fuel, such as hydrogen or methanol, into electricity. They can deliver more energy per volume and weight than batteries, even when including the volume and weight of the stored fuel.
In the future, automobiles will probably operate on fuel cells alone, or with a hybrid system using both batteries and fuel cells in which the battery provides power for acceleration and speed and the fuel cell provides energy for longer distances before re-fueling.
All of the major automotive manufacturers are currently developing fuel cells as replacements for the conventional automobile engine to take advantage of the high efficiency and environmentally clean aspects of fuel cells.
Savinell is working with co-researchers C.C Liu, the Walter R. Persons Professor of Sensor Technology at the Case School of Engineering; Morton Litt, professor of macromolecular science at the Case School of Engineering, Jesse Wainright, a principal researcher, and Lauri Dudeck an engineer. Several students and staff researchers are also involved.
The team uses microfabrication technology to print multiple layers of fuel cell components onto a substrate that will permit low-cost, high-volume production of fuel cells rather than building them by hand. The goal is to produce fuel cells in a manner similar to the way that many types of integrated circuits are currently manufactured.
"The concepts used in semiconductor processing make it possible to fabricate thousands or millions of devices as easily and in the same time as it takes to fabricate one component by conventional processes. We have created inks for each of the materials needed to create the fuel cell, and discovered how to screenprint those inks onto a structure to form a functioning device," said Savinell. "This new miniature fuel cell ripens the conditions to someday create micro-systems, i.e., fuel cells coupled with electronic circuitry, micro processors, sensors, and transmitters on a single silicon chip."
The prototype device uses hydrogen, safely stored in a low-pressure hydride, as a fuel. An advanced version of the fuel cell, which would use methanol as a fuel to provide far greater energy storage capability, is under development.
Savinell's research is funded by $2.2 million in grants and contracts from the Defense Advance Research Projects Agency (DARPA), an arm of the U.S. Department of Defense. He says the military will most likely see this new micro-system technology first.
"Through technology transfer, the military could conceivably couple our fuel cell with miniature sensors that detect motion or even chemical warfare agents, add a transmitter that sends a signal to a remote receiver, and give a soldier advance warning of any threat," said Savinell.
Savinell noted that for the commercial market, the new miniature fuel cell could be used in everything from automobiles to cell phones and computers. "The major portion of the weight and volume of a portable computer or cell phone is the battery system. The size of the power pack is a major limitation for portable electronic devices," he said.