Scientists build dissolving batteries from gut bacteria

The researchers created the world’s first soluble battery powered by the same probiotics in yogurt and health supplements.

The equipment is built on water-soluble paper and can generate electricity for more than 100 minutes, and then dissolve harmlessly into the environment. This development solves the key challenge of transient electronic devices, namely creating power sources that disappear without leaving toxic residues. This innovation could allow new medical implants to monitor health and then dissolve safely in the body, eliminating the need for surgical removal.

The study, published in Small Journal, shows how 15 commercially available probiotic strains produce electricity while maintaining intact biosafety, a major advance in previous bacterial batteries that require careful treatment to prevent environmental pollution.

The fantasy of transcending the impossible mission

From spy movies to science fiction, the concept of self-destructive electronic devices has long captured imagination. However, there is a fundamental obstacle to creating real-world transient electronics: power supply.

“Transitonic electrons can be used in biomedical and environmental applications, but must be decomposed in a biosafety way,” said Seokheun “Sean” Choi, professor in the Department of Electrical and Computer Engineering at Binghamton University. “You don’t want to have toxic residues in the body. This type of device is called bioabsorbent electronics. The key challenge for transient or bioabsorbable electronics is power, but most power sources, such as lithium-ion batteries, include toxic materials.”

Traditional bacterial fuel cells have shown promise but can cause safety issues. Even bacteria classified as biosafety level 1 raise questions about environmental release and potential ecological destruction.

Probiotic solution

Cui’s team turned to an unexpected data: the same beneficial bacteria people consumed daily in supplements and fermented foods. The probiotic mixture of 15 therapies includes familiar names such as Lactobacillus and Bifidobacterium species, namely microorganisms with good safety and documented health benefits.

“There is sufficient literature to prove that probiotics are safe and biocompatible, but we are not sure if these probiotics have the ability to produce electricity,” Choi explained. “There is one problem, so she did a lot of experiments on it.”

The initial results proved disappointing. Probiotics are Gram-positive bacteria with thick cell walls that have limited ability to deliver electrons, which is the basic process required to generate electricity. Most bacterial fuel cells rely on Gram-negative species that evolve specifically for efficient electron transfer.

Engineering enhancement

Instead of giving up on this concept, doctoral student Maryam Rezaie designed a solution. The team developed a specialized electrode using polypyrrole (PPY) bound to zinc dioxide nanoparticles, resulting in a porous, rough surface that significantly improves bacterial performance.

Choi noted: “We did not give up. We designed the electrode surface using polymers and some nanoparticles, which may be preferable to bacteria.”

Cyclic voltammetry measurements show that when probiotics contact evidence of modified electrode-electron transfer energy, obvious redox peaks are found. The enhanced surface provides optimal conditions for bacteria to attach and grow, thereby significantly increasing its power generation potential.

Controlled dissolution technology

The team’s most innovative advancement involves precise control of device activation and lifespan. By encapsulating water-soluble paper substrates with Eudragit EPO, a pH-sensitive polymer, they create batteries that are activated only under specific acidic conditions.

This targeted approach has significant versatility. In a neutral environment, the device remains stable and inactive. However, under acidic conditions, such as contaminated areas, human stomach or contaminated soil-protective coating dissolves, exposes paper substrates and activates probiotics.

pH response design solves a variety of engineering challenges. When applying liquid electrode material, it prevents premature dissolution during the manufacturing process, achieves precise activation times and allows fine-tuning of operation duration from 4 minutes to over 100 minutes.

Technical performance and innovation

The optimized device generates a 4 micron power supply with 47 micro currents and an open circuit voltage of 0.65 volts. Although modest to conventional battery standards, this output is sufficient for low-power sensors, temporary medical monitors and environmental detection systems.

This study reveals fascinating insights into the electrochemistry of probiotics. Of these 15 strains, Lactobacillus species appear to be primarily responsible for power generation, while other strains may enhance the process by producing redox-active cofactors such as NADH and FLAVINS. This collaborative community approach is more effective than isolated bacterial strains.

Scanning electron microscopy confirms dense bacterial attachment to modified electrode surfaces, providing direct evidence for enhanced electron transfer mechanisms. Electrochemical impedance spectroscopy further demonstrates reduced charge transfer resistance, thus verifying the excellent performance of the probiotic-electrode interface.

Respond to irreversible challenges

A key finding from detailed electrochemical analysis: probiotic redox reactions exhibit largely irreversible behavior and have obvious reduction peaks, but weaker oxidation peaks. This suggests that bacteria favor reduced state or rapid reduction of species consumed before reoxidation, a finding that is of great significance to optimizing future designs.

The study also shows that the peak potential transfer as the scanning rate increases, confirming the irreversibility of the bacterial electron transfer process. This basic understanding enables more complex electrode engineering and bacterial community optimization.

Real-world applications

These implications go far beyond laboratory demonstrations. Temporary medical implants can monitor postoperative healing before harmless dissolution, track drug delivery or evaluate markers of infection. Environmental sensors can detect contamination in remote locations without retrieval. Security applications can enable a truly one-time monitoring device.

The horizontal interpolated electrode configurations demonstrated in the study have excellent scalability. Power outputs can be customized for a particular application by adjusting the electrode length or combining multiple units in a series or parallel arrangement.

Perhaps most importantly, dissolving a complete device will only leave behind beneficial microorganisms – which may actually improve the local microbiome rather than the organisms that contaminate them.

expect

Choi admitted that this represents an early proof of concept and conducted major research. “Other studies have to be done,” he said. “We used a mixture of probiotics, but I wanted to study separately which ones have additional electrical genes, and how synergistic interactions can improve power generation. And, in this study, we developed it in a single unit of biomaterials. I wanted to connect with them in series or parallel to improve power.”

Future work will focus on identifying specific probiotic strains with the best electrochemical properties, understanding community interactions that enhance power generation, and developing multi-unit systems for practical applications. Tests performed in simulated physiological environments and animal models are essential for biomedical applications.

As instant electronics evolved from science fiction to clinical reality, probiotic-driven batteries offer a unique biocompatibility solution to the most enduring challenges in the field, suggesting that sometimes state-of-the-art technology draws inspiration from micro-communities already living within us.

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