Electricity is also generated in each cell. Professor Seokheun Choi simulates this process with bacteria. His small energy harvesters provide electricity for weeks.

Batteries without lithium and rare earths – something like that would make battery technology far more environmentally friendly. One way to get there are “bio-accumulators”. They mimic the way normal cells generate energy. This is usually done by breaking down glucose. When the sugar is broken down by enzymes, electrons are also released in the process. Seokheun Choi, a professor at Binghamton University’s Thomas J. Watson College of Engineering and Applied Sciences, has found that the interaction of bacteria can generate enough energy to power devices.

Week-long operation

So far, his team has used two bacteria to generate the energy for biobatteries. The problem: These batteries only had a lifespan of a few hours. In a new version, three bacteria were used. All three bacteria work sequentially in separate chambers. “A photosynthetic bacterium produces organic food that is used as a nutrient for the other bacterial cells below. Below is the electricity-producing bacterium, the middle bacterium produces some chemicals to enhance electron transfer,” Choi said. This variant now supplies electricity for weeks.

Autonomous small devices

The three cells are housed in a square with an edge length of three centimeters and a height of about one centimeter, the so-called energy harvester. The cubes can be scaled as desired, like Lego bricks they can be connected to each other until they deliver the desired voltage and current. The field of application of the bio-batteries should be small, smart devices or robots that operate independently in areas without a power supply. In the “Internet of Things”, wireless sensor networks are being set up that are used in remote and difficult environments. These sensors have to work without a power supply and also without regularly changing an empty battery.

“Thanks to artificial intelligence, we will have an enormous number of intelligent, standalone, always-on devices on very small platforms. How do you power these miniaturized devices? The most demanding applications will be the devices that operate in unattended environments. We can’t go there going to swap out the batteries, so we need these miniaturized energy harvesters.” The next step is the development of self-healing modules that can independently repair damage. The long-term goal is an extreme miniaturization of the technology. “We call this ‘smart dust’ and a few bacterial cells can generate energy in it. We can scatter it wherever we need it.”

The emphasis of the technique is on “small”. The photosynthesis of the first layer of bacteria provides the energy input, the high energy requirements of an electric car will not be covered in this way.

What: Binghamton