Materials science

Jelly blocks that send a message

Glowing mosaics can be sliced and diced to change their encrypted content.

Information can be encoded in a mosaic of fluorescent gel cubes, and can be easily manipulated by changing the cubes’ positions.

Jonathan Sessler at the University of Texas at Austin and his colleagues devised a recipe for sticky gel cubes that glow red, blue or green when illuminated with ultraviolet light. When 25 cubes were pushed together, they adhered to form a rough square. The team programmed a smartphone to display a designated website when the phone detected a square with a particular colour pattern.

The researchers could mask the encoded information physically, by excising one gel cube, or chemically, by sprinkling the cubes with a compound that quenched their colours. The mosaic could also be cut and the cubes rearranged to form a pattern that triggered the display of a second website.

The soft gels could be incorporated into smart clothing, the authors say.