After taking a new approach to developing an effective "electronic tongue" that mimics human taste, scientists in Illinois are reporting development of a small, inexpensive, lab-on-a-chip sensor that quickly and accurately identifies sweetness — one of the five primary tastes. It can identify with 100 percent accuracy the full sweep of natural and artificial sweet substances, including 14 common sweeteners, using easy-to-read color markers. This sensory "sweet-tooth" shows special promise as a simple quality control test that food processors can use to ensure that soda pop, beer, and other beverages taste great, — with a consistent, predictable flavor.The new sensor, which is about the size of a business card, can also identify sweeteners used in solid foods such as cakes, cookies, and chewing gum. In the future, doctors and scientists could use modified versions of the sensor for a wide variety of other chemical-sensing applications ranging from monitoring blood glucose levels in people with diabetes to identifying toxic substances in the environment, the researchers say.
"We take things that smell or taste and convert their chemical properties into a visual image," says study leader Kenneth Suslick, Ph.D., of the University of Illinois at Urbana-Champaign. "This is the first practical "electronic tongue" sensor that you can simply dip into a sample and identify the source of sweetness based on its color."
Researchers have tried for years to develop "electronic tongues" or "electronic noses" that rival or even surpass the sensitivity of the human tongue and nose. But these devices can generally have difficulty distinguishing one chemical flavor from another, particularly in a complex mixture. Those drawbacks limit the practical applications of prior technology.Suslick's team has spent a decade developing "colorimetric sensor arrays" that may fit the bill. The "lab-on-a-chip" consists of a tough, glass-like container with 16 to 36 tiny printed dye spots, each the diameter of a pencil lead. The chemicals in each spot react with sweet substances in a way that produces a color change. The colors vary with the type of sweetener present, and their intensity varies with the amount of sweetener.