A team of researchers from the University of Texas at Austin has developed a device that mimics the function of the human tongue. The electronic device contains a 3 x 3 array of polyethylene glycol/polystyrene beads bearing chromogenic indicator molecules. These molecules, which act as "taste buds," are inside micromachined wells patterned after the tiny cavities that hold taste buds in the human tongue. When exposed to different solutions, the beads change to intensities of red, green and blue, and a charge-coupled device records the changes. The indicator molecules are selective, responding to the presence of simple sugars, pH, pH plus Ca2+, and pH plus Ca2+ and Ce3+.