For years, scientists have been experimenting with "biobots." Example include insects fitted with various electronic systems that can harvest kinetic energy from their wings, those that use the Xbox's Kinect interface to follow a set path, and those put to work mapping building interiors. Now, engineers at Washington University in St. Louis are developing a method to tap into the highly-tuned olfactory system of locusts, using them like tiny cyborg sniffer dogs to detect the smell of chemicals used in explosives.

Leading the project is Baranidharan Raman, Associate Professor of Biomedical Engineering at WUSTL, who has previously conducted research into the sensory systems of locusts. Those studies determined how the insects' brains light up in response to olfactory stimuli, and found that even when clouded by other smells, locusts are able to single out odors they've been trained to identify.

Since the locusts' natural chemical-sensing system is far more powerful than any artificial ones, Raman plans to harness the power of that nose, attaching miniature electronics to the insects that monitors their brains and determines, through their neural activity, which chemical compounds the locusts are detecting.

"Why reinvent the wheel? Why not take advantage of the biological solution?" says Raman. "That is the philosophy here. Even the state-of-the-art miniaturized chemical sensing devices have a handful of sensors. On the other hand, if you look at the insect antenna, where their chemical sensors are located, there are several hundreds of thousands of sensors and of a variety of types."

Raman and the team will steer the locusts in flight using techniques similar to how scientists were able to remotely control cockroaches. Previous studies have shown that locusts will naturally turn away from sources of heat, so the researchers plan to develop a plasmonic "tattoo" that can be applied to the insects' wings, which will generate mild heat on command and allow the team to steer the bugs in the desired direction. These tattoos will be made of a biocompatible silk, and contain plasmonic nanostructures that can collect samples of chemicals in the environment for later study.

Raman says that the canine olfactory system is still top-dog for security and medical applications, but notes that the effort and time required to train them, as well as the difficulty in retrieving the information from their more developed brains, can be a hurdle. With more research, locusts could prove a viable alternative for some applications.

"We expect this work to develop and demonstrate a proof-of-concept, hybrid locust-based, chemical-sensing approach for explosive detection," says Raman.