Though pacemakers require only small amounts of energy (about 1 millionth of a Watt), their batteries have to be replaced periodically, which means multiple surgeries for patients. Researchers have searched for ways to prolong battery life -- trying to generate energy to power a pacemaker using blood sugar, or the motion of the hands and legs -- but these methods either interfere with metabolism or require a more drastic surgery, such as passing a wire from the limbs to the chest area.
