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Smart Gels

Toyo One of the most popular labs at MIT is the one directed by Toyoichi Tanaka, whose polymer gels have shown their potential to transform the technology of medicine, energy, food production and manufacturing.

Born and raised in Japan, Tanaka received his higher education at the University of Tokyo, where he earned a B.S. (1968), M.S. (1970), and D.Sc. (1973), in Physics. In 1975, he joined the faculty of MIT, where he has risen to the rank of Professor of Physics as well as Morningstar Professor of Science.

Tanaka's field of expertise is gels. A gel is typically a mixture of a polymer "matrix," that is, a chain of individual molecules, and a fluid "solute," in a ratio of about 1:30. The obvious example is Jell-O™, which has a matrix of gelatin in a solute of sugar water. However, synthetic gels can be made in which the polymers are very tightly bonded---with sometimes surprising results.

In the mid-1970s, Tanaka discovered that certain synthetic (polyacrylamide) gels had remarkable properties: for example, they responded to minute changes in their environment by drastically swelling up or changing color. Any substance will respond to its environment to some extent; but Tanaka learned to fine-tune his gels to undergo radical changes, or "phase transitions," when they encounter either a chemical or a change in conditions (temperature, light, electricity, magnetism, etc.).

At this stage, Tanaka's gels have valuable applications because they can expand and contract up to 1,000 times their original volume in response to predictable stimuli: for example, these gels could be used as artificial muscles, set in motion by a specific electrical pulse. More importantly, the polymers in the gels can capture or expel specific substances as they grow or shrink, so that the gels could be used, for example, as super-sponges to absorb and immobilize toxic waste, or as molecular filters of various sorts.

The more complex stage of Tanaka's research has been to develop "smart" gels which imitate proteins by recognizing conditions and responding to their environment. For example, smart gels can be fine-tuned to draw humidity from the air when it is over a given temperature, or even to release insulin when the glucose level around them drops below a given point.

By 1992, Tanaka had earned eight patents for his gels. In the same year, he and a partner founded Gel Sciences, Inc., in order to market SmartGel products. Their first effort was a liner for shoes and skates, which is pliant until it encounters the body heat of the foot; then it firms up to provide custom-molded support. More recently, the firm has focused on medical applications of the gels, such as long-lasting eyedrops and sunscreen; and numerous drug delivery systems are in production.

Meanwhile, Tanaka continues his research at MIT, while technologists in many disciplines monitor his progress carefully: in 1996, Tanaka won both the R&D 100 Award and Discover Magazine's Editor's Choice for Emerging Technology Award. Although Toyoichi Tanaka has been the world's leading expert on gels for almost 20 years, it is clear that his greatest success is still to come.

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