Wearable technologies are redefining the ways by which humans exchange information, receive entertainment, and monitor health and fitness. Although traditional electrochemical batteries are available to power these electronics, their limited lifetime and incompatibility with biology are not ideal for powering devices that interface with the human body. It is therefore compelling to explore novel power sources that can be fueled by the activity of the wearer. Without needing to be “plugged in”, these power sources could integrate seamlessly into daily life. The knifefish of the genus Electrophorus, commonly known as electric eels, provide a potent example of the ability to generate electricity from metabolic energy. Electric eels use the flux of ions across the membranes of their electrically-active cells (known as “electrocytes”) to produce external electrical discharges of over 800 V and 1 A. Within the electric organs of electric eels, arrays of thousands of electrocytes fire simultaneously to generate each electric discharge.