Researchers from the University of California, San Diego have developed a living neon sign that emits light from fluorescent bacteria. The bacteria light up when exposed to low levels of arsenic, allowing them to become illuminated in unison.
Described as biopixels, each unit contains between 2.5 - 60 million bacterial cells. These pixels can then be built into chips to create larger areas of light.
Hypothetically, the same system can be used to allow bacterial sensors to detect pollutants and other harmful chemicals, using colour and light as a warning indication.