It's not speedier than normal, but it sure is powerful. By implanting enzyme-coated electrodes into a snail, researchers have turned the invertebrate into a tiny fuel cell. The enzyme coating one electrode triggers a chemical reaction that consumes glucose produced by the snail and generates electrons. A different enzyme coating the other electrode takes spare electrons and gives them to positive ions in the snail's hemolymph, the invertebrate equivalent of blood. Together, these reactions created a voltage difference between the electrodes of a little more than 0.53 volts, generating power of a few microwatts, the researchers report in Journal of the American Chemical Society. (For comparison, the power generated by the solar cells in calculators and watches often are measured in microwatts.) The snail-based fuel cell—the first such implant to operate for an extended time without harming its host animal, the researchers claim—provided power for months, with power dropping when the glucose supply lagged and then surging again after the snail rested or ate. Improving the efficiency of chemical reactions at the electrodes could garner more power. Future generations of such fuel cells could power pacemakers or insulin pumps, for example, eliminating the need to change batteries regularly. Or, the electricity generated by similar implants in creatures such as worms or insects could one day power spy cameras or tiny microphones, or drive sensors that monitor the environment. In the meantime, watch what you say: The snails may be listening.
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