Optical fingerprinting

Supercharged biomacromolecules can maintain their reordered structures induced, for example, by a fingertip touch, according to work by scientists in China and The Netherlands. Stimuli-sensitive materials respond to physical forces with structural phase transitions and this also applies to biopolymer-surfactant mixtures, the team reports. The system uses a complex of a supercharged polypeptide with a cationic surfactant. This viscous liquid adopts birefringence patterns after being touched and so can reveal details such as fingerprints.