In all cases, it is believed that the animals sense chemicals that humans emit through body odor or breath. The mix of chemicals can vary depending on a person’s metabolism, which is thought to change when we get sick. But dogs are expensive to train and care for. And it has proven extremely difficult to create a device that mimics a dog’s nose, says Debajit Saha, one of the scientists behind the last workthat has not yet been peer-reviewed.
“These changes are almost in parts per trillion,” said Saha, a neural engineer at Michigan State University. This makes them difficult to pick up, even with the most modern technologies, he adds. But animals have evolved to interpret such subtle changes in smells. So he and his colleagues decided to “hijack” an animal brain instead.
THANKS TO THE RESEARCHERS
The researchers chose to work with grasshoppers because these insects have been well studied in recent years. In a preliminary setup, they surgically exposed the brain of a living grasshopper. Saha and his colleagues then placed electrodes in the lobes of the brain that receive signals from the insects’ antennae, which they use to sense smells.
The team also cultured three different types of human oral cancer cells, as well as human mouth cells that were cancer-free. They used a device to capture gas emitted by each of the cell types, and delivered each of these to the antennae of the grasshoppers.
The locusts’ brains responded differently to each of the cell types. The recorded patterns of electrical activity were so clear that when the team puffed the gas from one cell type onto the antennae, the recording alone allowed them to correctly identify whether the cells were cancerous.
It’s the first time a live insect brain has been tested as a cancer-detecting tool, Saha says.
Natalie Plank, who is developing nanomaterial-based health sensors at the Victoria University of Wellington in New Zealand, thinks the work is ‘super cool’. “The potential of just being able 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 brain recordings from multiple grasshoppers and combined their responses. It currently takes recordings from 40 neurons to get a clear signal, meaning the system needs between six and ten locust brains. But Saha hopes to use electrodes that can record from more neurons, giving him recordings from the brain of a single grasshopper. He also hopes to be able to use the brain and antennas in a wearable device, which can then be tested on real people.