Profs. David Blaauw and David Wenzloff are designing millimeter-scale ultra-low-power sensing systems that can be injected into the body through a syringe. Unlike other radios of this size, these new devices are able to broadcast through the human body to an external receiver.
This device came from a group of researchers in the Michigan Integrated Circuits Lab responsible for the Michigan Micro Mote(M3), currently the world’s smallest computer. This platform has enabled a variety of sensors that can fit inside the human body, made possible by several breakthroughs in ultra-low power computing.
Once a device is implanted in the body, its ultimate usefulness depends not only on its ability to assess essential information, but to transmit that data to someone who can act on it. A typical radio would need an antenna larger than the M3 to transmit more than a few centimeters, and more power than could be generated from the tiny battery alone.
Thanks to a novel approach to antenna design, the computer was able to send radio signals 50 centimeters (or nearly 20 inches) away – which is easily sufficient to reach a receiver outside the body. To achieve the burst of power needed to transmit the data, the team integrated a capacitor into the device that is able to gradually build up a sufficient amount of power from the tiny battery before passing it along to the antenna, enabling data transmission in periodic bursts.