Engineers at Stanford University have demonstrated a tiny self-propelled device that can travel through the bloodstream in a controlled manner, potentially leading to a diagnostic and drug delivery revolution. 
The new device was presented by electrical engineer Ada Poon at the International Solid-State Circuits Conference (ISSCC) in San Francisco, California.
A common problem faced by implantable medical devices is a power source. A common workaround is to supply power wirelessly using inductive currents, avoiding the need for a bulky battery. Conventionally, high frequency radio waves are believed to conduct poorly in human tissue, so low frequency waves are used instead. However, these low frequencies require much larger coils, and therefore a bulkier device. Poon discovered, using the power of math, that high-frequency radio waves conduct in human tissue much more effectively than previously thought, and thus was able to engineer a much smaller device that is able to deliver equivalent power. Now Poon is deciding the best way to propel this remarkable device through the bloodstream. One concept involves using alternating electrical currents to make the device wobble back and forth to propel itself almost like a microscopic kayak. There are many possible applications for this new device concept, including delivering drugs and as a diagnostic tool.
Press release: Tiny, implantable medical device can propel itself through bloodstream