Supercooled Liquid that Glows When Touched Has Electronic Applications

A new material developed at the University of Michigan stays liquid more than 200 degrees Fahrenheit below its expected freezing point, but a light touch can cause it to form yellow crystals that glow under ultraviolet light. Even living cells sitting on a film of the supercooled liquid produce crystal footprints, which means that it's about a million times more sensitive than other known molecules that change color in response to pressure. The material could have applications as a new kind of sensor for living cells, while the mechanism behind its unusual properties may guide the development of electronics and medicines. In addition to the unusually broad temperature range for the supercooled liquid state, the group found that it crystallized when rubbed with a stylus, changing from dark red to bright yellow. The rubbing broke the stalemate between the two ways for the molecules to connect, allowing the side chains to link up. At room temperature, the thicker supercooled liquid crystallized only where the stylus made contact, allowing the researchers to write messages such as 'shear-triggered crystal.'