Get this: A cockroach has been turned into a fuel cell.
A team at Case Western Reserve University led by Michelle Rasmussen and Daniel Scherson has tapped into the metabolic system of a cockroach to produce electricity. This isn't the first time anyone has tried building a cyborg bug of sorts. A University of Michigan team tried it using piezoelectric materials. What's interesting here is that Rasmussen's group used the insect's own body chemistry to produce electricity.
When a cockroach eats, it produces a sugar called trehalose, which is broken down by one set of enzymes in the cockroach's blood, called haemolymph. It takes several steps for different enzymes to finish breaking down and converting sugars for food, but in the last step, electrons are released.
By inserting a wire into the cockroach, the scientists were able to tap into the electrons and harness the electricity. The amount of power isn't huge, only about 50 to 60 microamperes per square centimeter at 0.2 volts. But it's a proof of principle that shows that an insect's own body could be used to power tiny devices, such as sensors and microphones into places that would be otherwise out of reach.
And in case you're concerned by the little roach's comfort, inserting the wire doesn't hurt it, in part because cockroaches don't have blood vessels. They have an "open" circulatory system, which simply bathes organs in haemolymph. Consequently there is no pressure, so puncturing a cockroach with an electrode isn't as much of a problem as it is for a vertebrate.
Trehalose is present in the circulatory systems of many insects, and some have even higher concentrations than cockroaches do. It's also present in mushrooms. The team tested shiitakes, and got current from there as well.