Ants are some of the most organized living things on the planet. They build highly sophisticated colonies for future generations, enslave other ants, pillage, maintain the nest, and send foragers out for food. And they do all this without speaking. Well, sort of.
Like many animals, ants communicate by pheromones. Step on an ant’s head, and the chemicals gushing from its glands will tell its friends to attack. Tiny bacteria also communicate on this molecular level. Now, a Canadian group of scientists say that bacteria, too, can send messages by chemicals, according to a study published in the open-access journal PLoS One. While work in this field has largely been theoretical to this point, researchers say that new practical knowledge of this method could dramatically increase channels of communication in human technologies that require sensing, with applications in everything from environmental monitoring to fighting cancer.
"In traditional communication devices, we use electronic signals. The idea behind molecular communication is that you use chemical signals," says Nariman Farsad, an electrical engineering PhD student at York University, who led the study. (He notes that electronic signals don’t always work in metallic structures, under rubble, or in water. They’re also inefficient on the molecular level.)
Farsad and a team of collaborators designed a tabletop experiment with a sensor at one end and a spray bottle of rubbing alcohol at the other. The sensor could register concentrations of the alcohol content, so the researchers assigned the spritzing a code: 1 meant a spritz, 0 no spritz. Through 5-digit codes assigned to letters, they managed to pass along a molecular message hammered out in modified Morse: O CANADA, they sprayed with national pride.
Say, for example, scientists develop nano-robots to search and destroy cancerous cells. Once a patient is injected, the sensor robot and the destroyer robot would need a way to communicate, and Farsad suggests they ought to do so by molecule.
He also sees urban health monitoring as a potential application. "It’s very challenging to use radio communication inside metallic structures, so you could put the chemical sensors in a bridge," Farsad said. "Another is urban search and rescue. Say there’s an earthquake, and you want to send a bunch of robots into the rubble to look for survivors. But once the robots go under the rubble, it’s hard to get a radio sensor under the rubble. The robots could communicate through chemical signals."
Farsad’s molecular communication still has a long way to go. So far, his team’s just demonstrated that it can work at a four-meter distance. But Farsad and his collaborators certainly aren’t the only ones who have thought about the promise of chemical messaging. The National Science Foundation has funded researchers at the Georgia Institute of Technology with a four-year, $3 million grant to study how bacteria communicate, and see if it can apply the findings to nanotechnology that can detect viruses and tumors.
The York University team happily admits they don’t have all the answers, and would love for other multidisciplinary groups to collaborate on applications. "We’re hoping our paper will attract more scientists," Farsad said.