Electronic tongue analyzes flavors.

An artist may complain that a critic's taste is only in his mouth. But University of Texas (Department of Electrical and Computer Engineering, Engineering Science Building 143, Austin, TX 78712) engineers and scientists have now successfully placed it on a silicon chip. Using chemical sensors, the researchers have designed an electronic tongue that mimics the real thing. In some ways it has outdone Mother Nature. The device has the capacity to analyze the chemical composition of a substance as well.

Like its natural counterpart, the device has the potential to distinguish between a dazzling array of subtle flavors by combining the four elements of taste: sweetness, sourness, saltiness and bitterness. Researchers have used the device to analyze fruit juices, soft drinks and wine. Some companies have shown an interest in the work.

The e-tongue, which has the potential to incorporate hundreds of chemical microsensors on a silicon wafer, will find a multitude of uses. The food and beverage industries could develop it to rapidly test new food and drink products to compare them with tastes that are popular with consumers. But the artificial tongue can also be used to analyze cholesterol levels in blood, cocaine in urine or toxins in water. The U.S. National Institutes of Health recently gave the Texas group $600,000 to develop a version of their tongue that might replace several medical tests done on blood and urine with one fast test.

The tongue research began in 1996 when electrical and computer engineers first considered the concept. The scientists had already designed a nose to sniff out iodine, but soon realized that many chemicals don't evaporate.

The collaboration has incorporated the work of chemists who have used polymer microbeads to synthesize DNA and its proteins. The team attaches four well-known chemical sensors to the minute beads and places the beads in micro-machined wells on a silicon wafer. Like a human tongue, the wells mimic the tongue's many cavities that hold chemical receptors known as taste buds. Each bead, as a tongue's receptor, has a sensor that responds to a specific chemical by changing color. One turns yellow in response to high acidity and is purple under basic conditions.

The sensors respond to different combinations of the four artificial taste elements with unique combinations of red, green and blue, enabling the device to analyze several different chemical components simultaneously. This is where the group employed the expertise of chemists who developed the dye photochemistry.

From the silicon tongue, the group hopes to create a process to make artificial tongues more cheaply and quickly, so that they can be placed on a roll of tape, for example, used once and thrown away. The researchers have submitted a series of scientific publications demonstrating the use of their artificial tongue and have applied for several patents.

Further information. Dean Neikirk; phone: [phone]; fax: [phone]; email: [e-mail].