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Development of a prototype battery at Binghamton University in New York State was prompted by a sci-fi inspired question: “Could electronics disintegrate into nothing in real life?”
Professor Seokheun ‘Sean’ Choi has researched disposable ‘papertronics’ for the last 20 years, but the hardest part part of making ‘transient electronics’ is the battery.
“Transient electronics can be used for biomedical and environmental applications, but they must disintegrate in a biosafe manner,” said Choi, a faculty member at the Thomas J Watson College of Engineering and Applied Science.
“You don’t want to have toxic residues inside your body. That type of device is called bioresorbable electronics. For transient or bioresorbable electronics, the key challenge is the power source — but most power sources, like lithium-ion batteries, include toxic material.”
Choi and his student research team took lessons from their previous research into biobatteries and applied that knowledge to the new idea of using probiotics, live microorganisms that offer health benefits when ingested but are otherwise harmless to the environment and humans.
A previous dissolvable microbial fuel cell was developed by Maedeh Mohammadifar during her time as a Binghamton student.
“We used well-known electricity-producing bacteria, which is within biosafety level one, so it is safe – but we were not sure what would happen if these bacteria were released into nature,” Choi said. “Whenever I made presentations at conferences, people would ask: ‘So, you are using bacteria? Can we safely use that?’”
Current PhD student Maryam Rezaie led the latest research using a premade blend of 15 probiotics.
“It’s well documented that probiotics are safe and biocompatible, but we were not sure if those probiotics have electricity-producing capability,” Choi said. “There was a question, so she did a lot of experiments on that.”
Early results proved unpromising, he added, but “we didn’t give up. We engineered in an electrode surface that might be preferable to the bacteria, using polymer and some nanoparticles to hypothetically improve the electrocatalytic behavior of probiotics and give them a boost.”
The modified electrode was porous and rough, which reportedly offered “excellent” conditions for bacteria to attach and grow, improving the microorganisms’ electrogenic capability. Coating the dissolvable paper with a low pH-sensitive polymer – meaning that it will work only in an acidic environment, such as the human digestive system – increased the voltage output and the duration that the battery operated.
A single module outputs 4 microwatts of power, 47 microamperes of current, and an open-circuit voltage of 0.65V. Although they produced only a small amount of power, Choi said the experiments are a proof of concept for him and future students to build on.
“Other research must be done,” he said. “We used probiotic blends, but I want to study individually which ones have the extra electric genes, and how synergistic interactions can improve the power generation. Also, in this research we developed in a single unit of a biobattery. I want to contact them in series or parallel to improve the power.”
The work was published in Small.
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