Relating automobile shock absorbers and chocolate bars would seem to be stretching the bounds of credulity, but research on this relationship is ongoing. James Steffe, Ph.D., a Michigan State University professor of agricultural engineering, and Christopher Daubert, Ph.D., then a graduate student in the same field, now teaching at North Carolina State University, found that when a moderately high electric field is applied to molten Hershey bars, an almost instantaneous change occurs: the thin chocolate liquid becomes a stiff gel. This warm, tasty fluid is transformed into a semisolid within a few thousandths of a second after the electric field is applied, and it reverts to a liquid just as fast when the power is shut off. This behavior is called electrorheology, or the study of changes in the viscosity of fluids in response to electricity.
Liquids that undergo this change are called “smart liquids” because they can continuously and rapidly respond, through computer controls, to changes in a machine’s environment, including the potholes that disrupt the smooth ride of a car over a road. This capability, named the “Winslow effect” for its discoverer, Dr. Willis M. Winslow, has been under experimentation by various automobile groups with the goal of developing an electrorheo-logical fluid that could be used for clutching in automatic transmissions. Other suggested uses include ultra-fast hydraulic valves with no moving parts, vibration isolation devices to make submarines and automobiles quieter, high-speed control actuators for airplanes and robots, and fast-acting valves for ink-jet computer printers.
Automotive Engineering magazine predicted eight years ago that such applications could become a $20-billion-a-year business. According to Dr. Kathleen Habelka, a chemist who participated in such testing, pure research in electrorheology is being pursued actively in Japan, but funding has practically dried up in the U.S. — Barbara A. Johnston
[New York Times. 1996. Chocolate: The Stuff of Shock Absorbers? Sept. 24.]