In all cases, the animals are thought to be sensitive to chemicals that are released by body odor or breath. The combination of chemicals can vary depending on a person’s metabolism, which is thought to change when we get sick. But training and caring for dogs is expensive. And a device that mimics a dog’s nose has proved extremely difficult to create, says Debajit Saha, the scientist behind the latest work, which has not yet been peer-reviewed.
“These changes are in parts of a trillion,” says Saha, a neural engineer at Michigan State University. This makes them difficult to choose despite having sophisticated technologies, he adds. But animals have evolved to interpret such subtle changes in scent. So he and his comrades decided to “hijack” the animal’s brain instead.
Researchers chose to work with locusts because these insects have been well studied in recent years. In the initial setup, they surgically exposed the brain of a live locust. Saha and his colleagues then inserted electrodes into the lobes of the brain that receive signals from the insect’s antennae, which they use to detect odors.
The team also developed three different types of human oral cancer cells as well as human oral cells that were cancer free. They used a device to get the gas emitted by all kinds of cells, and deliver each of them to the locust antennae.
The locust brain responds differently to each type of cell. The pattern of electrical activity recorded was so different that when the team puffed gas from one type of cell onto the antenna, they were able to correctly identify whether the cells were cancerous just by recording.
For the first time, the brain of a living insect has been tested as a means of detecting cancer, says Saha.
Natalie Planck, who is developing nanomaterial-based health sensors at Victoria University of Wellington, New Zealand, thinks the work is “super cool”. “The ability to breathe on something and then know if you’re at risk for cancer is really powerful,” she says.
In the experiment, the team took recordings of multiple locust brains and collected their responses. It currently takes recordings from 40 neurons to receive a clear signal, which means the system needs six to 10 locust brains. But Saha hopes to use electrodes that can record from more neurons, which will allow him to get recordings from a locust’s brain. It also hopes to be able to use brains and antennas in a portable device, which can then be tested on real people.