For decades, the U.S. Defense Department has been implanting remote-control electrodes inside flying insects during their pupae stage (caterpillar) so that when they metamorphose into winged creatures (moths) their flight can be controlled by wireless neural stimulation. Now researchers at the University of Michigan are perfecting self-powered video, audio and gas sensors so the tiny cyborgs can perform reconnaissance during military surveillance, monitor hazardous environments and assist first-responders in search-and-rescue missions.
The Defense Advanced Research Project Agency (DARPA) has been funding cyborg insect development that combines wireless transmissions to neural implants that allow humans to control insects' flight patterns the same way a horse is guided by reins. Called the Hybrid Insect Micro Electromechanical System (Hi-MEMS), the technique installs wireless implants before birth, so that the insects accept human-directed flight control commands as if they were a part of their natural nervous system.
Insects are fitted with sensors powered by piezoelectric generation from muscle movement as well as thermal harvesting of body heat. (Source: University of Michigan)
In addition to flight control, the Hi-MEMS program has been experimenting with tapping into the native sensors already a part of insect physiology, such as training bees to use their olfactory senses to locate explosives, mines and chemical weapons. By harnessing natural olfactory sensors (nose) powered by biochemical storage (fat), military surveillance controlled by bio-actuators (muscle) can be performed by insects that appear to be normal.
However, for many reconnaissance tasks, a different complement of sensors and actuators is needed other than those built in to the insect. Hi-MEMS has several projects under way to install resonant piezoelectric, magnetic- and thermo-electric-generators, as well as non-resonant broadband energy scavengers. And to power tiny MEMS sensors for video, audio and gas sensors, a University of Michigan team recently displayed its designs for energy harvesting devices that convert muscle motion into usable energy to power the MEMS.
Called energy scavenging by University of Michigan Prof. Khalil Najafi and doctoral candidate Erkan Aktakka, the researchers claim that their techniques aim to make insect cyborgs into useful tools for reconnaissance.
"We could potentially power cameras, microphones and other sensors and communications equipment that an insect could carry," said Najafi. "We could then send these 'bugged' bugs into dangerous or enclosed environments."
One of the most promising energy harvesting approaches being tried by the researchers is tapping into the strong wing muscles, using tiny piezoelectric coils to generate electricity that powers on-boards sensors and a radio transmitter. Harvesting kinetic energy from wing motion kept a tiny battery charged for powering video, audio and gas sensors that stream back data to the operators controlling the insect's flight. The tiny coiled piezoelectric generator was machined from bulk piezoelectric material using a femtosecond pulsed laser at the University of Michigan's Lurie Nanofabrication Facility.