Engineers at Binghamton University have developed the first dissolvable battery powered by probiotics, addressing a critical challenge in the design of transient electronics. The device generates electricity for over 100 minutes before harmlessly dissolving, potentially enabling medical implants that monitor health conditions and then safely disappear without surgical removal.
The research, published in the journal Small, demonstrates how commercially available probiotic strains can generate electricity while maintaining complete biosafety—a significant advancement over previous bacterial batteries that required careful disposal to prevent environmental contamination.
Professor Seokheun “Sean” Choi from Binghamton University’s Department of Electrical and Computer Engineering has spent two decades developing disposable “papertronics”—electronic circuits fabricated on biodegradable paper substrates. The most persistent obstacle has been creating compatible power sources.
“Transient electronics can be used for biomedical and environmental applications, but they must disintegrate in a biosafe manner,” Choi explained. “You don’t want to have toxic residues inside your body. For transient or bioresorbable electronics, the key challenge is the power source—but most power sources, like lithium-ion batteries, include toxic material.”
Traditional bacterial fuel cells have shown promise but raised safety concerns about environmental release and potential ecological disruption, even for bacteria classified as biosafety level 1, which have generated questions about their impact if released into natural ecosystems.
Choi’s team turned to an established safe alternative: the same beneficial bacteria people consume daily in supplements and fermented foods. The research utilised a commercial blend of 15 probiotic strains, including familiar species such as Lactobacillus acidophilus and Bifidobacterium—microorganisms with well-documented safety profiles.
PhD student Maryam Rezaie led the investigation into probiotic electricity-generating capabilities. Initial results proved disappointing, as probiotics are Gram-positive bacteria with thick cell walls that limit electron transfer—the fundamental process needed for electricity generation.
Rather than abandoning the concept, the team engineered a specialised electrode using polypyrrole conjugated with zinc oxide nanoparticles. This created a porous, rough surface that dramatically improved bacterial performance by providing optimal conditions for attachment and growth.
The team’s most innovative advancement involves precise control over device activation and lifespan. By encapsulating the water-soluble paper substrate with EUDRAGIT EPO—a pH-sensitive polymer—they created batteries that activate only under specific acidic conditions.
This targeted approach offers versatility for different applications: • In neutral environments, the device remains stable and inactive • In acidic conditions such as the human stomach or contaminated soil, the protective coating dissolves • The pH-responsive design enables precise timing of activation • Operational duration can be tuned from 4 minutes to over 100 minutes.
The optimised device generates four microwatts of power with a current of 47 microamps and an open-circuit voltage of 0.65 volts. While modest by conventional battery standards, this output suffices for low-power sensors, temporary medical monitors, and environmental detection systems.
Scanning electron microscopy confirmed dense bacterial attachment to the modified electrode surface, providing direct evidence for enhanced electron transfer mechanisms. Electrochemical impedance spectroscopy demonstrated reduced charge-transfer resistance, validating the superior performance of the probiotic-electrode interface.
Deep Technical Analysis of Probiotic Electrochemistry
Fundamental Electrochemical Mechanisms
The transition from traditional bacterial fuel cells to probiotic-powered systems required overcoming significant electrochemical barriers. Gram-positive probiotics possess fundamentally different cell wall structures compared to the Gram-negative bacteria typically used in microbial fuel cells. The thick peptidoglycan layer in the cell walls of probiotics creates substantial resistance to direct electron transfer, necessitating innovative electrode engineering approaches.
Cyclic voltammetry measurements revealed distinct redox peaks when probiotics contacted the modified polypyrrole-zinc dioxide electrode, providing clear evidence of electron transfer capability. The research identified peak potential shifts with increasing scan rates, confirming the non-reversible nature of bacterial electron transfer processes. This irreversibility suggests probiotics favour reduced states or rapidly consume reduced species before re-oxidation can occur.
The breakthrough came through sophisticated surface modification techniques. The polypyrrole (PPy) matrix serves as both a conductive framework and a biocompatible interface, while zinc dioxide nanoparticles introduce catalytic sites that facilitate electron transfer. The resulting electrode exhibits: Increased surface area through controlled porosity, enhanced electrical conductivity via conjugated polymer networks, improved biocompatibility through biomimetic surface chemistry, and catalytic enhancement from nanoparticle integration
Surface characterisation using atomic force microscopy revealed roughness values optimised for bacterial adhesion. At the same time, X-ray photoelectron spectroscopy confirmed the successful incorporation of nanoparticles and the formation of chemical bonds between the polymer and metal oxide phases.
Among the 15 probiotic strains tested, Lactobacillus species demonstrated primary responsibility for electricity generation, while other strains enhanced the process by producing redox-active cofactors, including NADH and flavins. This synergistic community approach proved more effective than isolated bacterial strains, suggesting complex metabolic interactions optimize power output.
Metabolomic analysis identified specific pathways contributing to electrogenesis. Lactobacillus fermentation produces organic acids that create favourable pH conditions for electron transfer, while Bifidobacterium species generate cofactors that facilitate enzymatic electron transport chains. The research revealed that optimal power generation occurs when bacterial metabolism is synchronised with the electrode surface chemistry.
The EUDRAGIT EPO coating represents sophisticated pharmaceutical polymer technology adapted for electronics applications. This cationic copolymer responds to pH changes through alterations in its protonation state, which affects polymer solubility and permeability. At a neutral pH, the polymer forms a protective barrier that prevents premature device activation. As pH decreases below 5.5, progressive protonation causes polymer swelling and eventual dissolution.
The coating thickness directly correlates with activation timing, enabling precise control over the device’s lifespan. Polymer dissolution kinetics follow first-order mechanisms, allowing the mathematical modelling of activation profiles for specific applications. This predictable behaviour enables customization for diverse biomedical scenarios.
Moving from laboratory prototypes to practical applications requires addressing several engineering challenges. The horizontal interdigitated electrode configuration demonstrated optimal performance for single units, but series and parallel arrangements present complex impedance-matching requirements.
Power scaling follows predictable patterns: series connections increase voltage while maintaining current, and parallel connections multiply current while preserving voltage. However, bacterial loading effects create nonlinear scaling behaviours that require careful optimisation. Computational fluid dynamics modelling suggests optimal bacterial distribution patterns for multi-unit systems.
Manufacturing scalability depends on standardising electrode fabrication processes while maintaining the viability of biological components. The research identified critical process parameters, including polymer deposition conditions, nanoparticle distribution uniformity, and bacterial inoculation protocols that ensure consistent performance across production batches.
Advanced characterization techniques are revealing more profound insights into probiotic electrochemistry. Impedance spectroscopy across multiple frequency ranges identifies distinct time constants associated with different electron transfer mechanisms. Low-frequency responses correspond to bacterial metabolic processes, while high-frequency behaviours reflect electrode interface phenomena.
Genetic analysis of probiotic strains is identifying specific genes responsible for electron transfer capabilities. Some Lactobacillus strains possess cytochrome-like proteins that facilitate direct electron transfer, while others rely on mediator compounds. Understanding these genetic factors will enable the optimisation of strain selection for enhanced power generation.
The integration of advanced materials science with microbiology opens possibilities for engineered probiotic strains optimized for electrochemical applications. Synthetic biology approaches could enhance electron transfer efficiency while maintaining safety profiles essential for biomedical applications.
If the technology successfully scales beyond the proof-of-concept stage, applications could include temporary medical implants that monitor post-surgical healing, track drug delivery, or assess infection markers before dissolving harmlessly. Environmental sensors could detect pollution in remote locations without requiring retrieval, while security applications might enable truly disposable monitoring devices.
The complete device dissolution leaves only beneficial microorganisms that may improve local microbiomes rather than contaminating them. This represents a fundamental shift from viewing power sources as environmental liabilities to considering them biocompatible assets.
Choi acknowledges significant research remains ahead. “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 a single unit of a biobattery. I want to connect them in series or parallel to improve the power.”
Future work will focus on identifying specific probiotic strains with optimal electrochemical properties, understanding community interactions that enhance power generation, and developing multi-unit systems for practical applications. Testing in simulated physiological environments will be essential for biomedical applications.
The research represents early-stage proof of concept for addressing one of the most persistent challenges of transient electronics. By shifting from traditional toxic components to biologically benign probiotics, the team creates a foundation for sustainable electronics that could transform biomedical device design if development continues successfully.
TLDR:
- Engineers developed the first dissolvable battery powered by probiotics
- Device generates electricity for 100+ minutes before safely dissolving
- pH-sensitive coating enables activation only in acidic environments
- Could enable medical implants that disappear without surgical removal
- Uses the same safe bacteria found in yoghurt and health supplements
- Addresses major challenges in transient electronics power supply