The efficiency of microcontrollers, sensors, and various ICs has improved dramatically in recent years, and the Internet of Things is one major driving force behind that. A battery-powered IoT device needs to last a long time on a single charge, and because battery technology has remained fairly stagnant, that’s meant the only solution has been to improve efficiency. They’re so efficient that a new kind of paper battery may provide enough power for simple sensors.
This paper battery technology was developed by Seokheun Choi and his team at the State University of New York at Binghampton’s Department of Electrical and Computer Engineering. Unlike traditional batteries that store electricity in a chemical electrolyte, these rely on a special kind of bacteria called exoelectrogens. The bacteria are able to pass electrons through their cell membrane as part of their natural respiration process, and that process can be harnessed to provide a small amount of power.
To make the batteries, freeze-dried exoelectrogens are placed on a piece of paper with external electrodes. In that state, the bacteria are in a kind of stasis and will remain inactive. When moisture is added, the bacteria are revived and the battery starts working. Building the batteries is very inexpensive — just a few cents — and they’re much better for the environment than traditional batteries because they’re biodegradable. Unfortunately, the power output is too low to be practical for IoT right now, but Choi believes that can be improved with origami-style stacking techniques.