This neon sign is made of millions of living fluorescent Escherichia coli, a rod-shaped bacterium that lives in our intestines. Biologists and bioengineers at University of California, San Diego, synchronised them to glow at the same time.
Why is this important?
It may seem silly but, according to project director Dr. Jeff Hasty, their new bio-display will lead to the creation of gadgets that may save your life one day:
These kinds of living sensors are intriguing as they can serve to continuously monitor a given sample over long periods of time, whereas most detection kits are used for a one-time measurement. Because the bacteria respond in different ways to different concentrations by varying the frequency of their blinking pattern, they can provide a continual update on how dangerous a toxin or pathogen is at any one time.
In the future, we would be able to place one of these future devices on a subway, a public place or a factory and constantly monitor for the presence of pathogens and other harmful substances.
What are they made of?
Their largest bio-chips contain 50 to 60 million fluorescent E. coli cells, which result in about 13,000 biopixels, while the smallest ones have about 2.5 million, around 500 pixels.
How did they make them to glow in sync?
According to Hasty, "many bacteria species are known to communicate by a mechanism known as quorum sensing, that is, relaying between them small molecules to trigger and coordinate various behaviours." However, the quorum is too slow. It has too much latency and it propagates slowly from colony to colony.
But they discovered that the colonies can synchronise using a gas signal. That's the mechanism they used in their microfluidic chip to turn all the colonies into a controllable display.
How long until we see this technology in real products?
Hasty says that we may see the first gadget within five years, a hand-held sensor that would be able to detect "concentrations of various toxic substances and disease-causing organisms in the field." [UCSD]