Unleash your inner energy [human-body-based power sources]

As microelectronic devices get smaller and smaller, engineers are searching for novel ways to power them. One perhaps surprising option is the human body. With every breath, every heartbeat, and every step taken, the body is converting energy from one form to another. This article looks at efforts to harness this energy for use as a power source for devices from wristwatches and mobile phones to implantable biomedical devices and sensors.