World's smallest pacemaker is activated by light

Smaller than a grain of rice, new pacemaker is particularly suited to the small, fragile hearts of newborn babies with congenital heart defects. Tiny pacemaker is paired with a small, soft, flexible wearable patch that sits on the patient's chest. The wearable patch detects irregular heartbeats and automatically emits pulses of light. The light then flashes on and off at a rate that corresponds to the correct pacing. After the tiny pacemaker is no longer needed, it dissolves inside the body.