Professors David Blaauw and David Wenzloff of the Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, are designing millimeter-scale, ultra-low-power sensing systems that can be injected into the body through a syringe. Unlike other similarly-sized radios, these new devices are able to broadcast through the human body to an external receiver. The technology came from the group of researchers in the Michigan Integrated Circuits Lab that was responsible for the Michigan Micro Mote (M3), currently the world’s smallest computer.

Once a device is implanted in the body, it needs to not only 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.

A novel antenna design allows this computer 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.

The team is collaborating with researchers at the university’s medical school to test the device.

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