Power sources used in devices that operate in or around biological tissue must strike a delicate balance: they need to be flexible and non-toxic, yet powerful enough to support demanding technologies such as medical devices and soft robotics. Researchers at Penn State University have found inspiration in a rather “shocking” source: electric eels.
The team has developed a novel fabrication method that layers multiple types of hydrogels—a water-rich material capable of conducting electricity—in a pattern that mimics the ionic processes electric eels use to generate electrical bursts. This innovative approach results in power sources with higher power densities than other hydrogel-based designs, while remaining flexible, support-free, environmentally stable, and biologically compatible. Their groundbreaking findings were published in the journal Advanced Science.
Innovative Approach to Power Generation
According to Joseph Najem, assistant professor of mechanical engineering and corresponding author of the study, the biology of electric fish like eels has long inspired researchers to develop soft power sources. However, most existing eel-inspired devices produce limited power and require mechanical support to function effectively. To overcome these challenges, Najem’s team adjusted the material chemistry to fabricate ultra-thin hydrogels, enabling them to produce more power without mechanical supports.
“The electrocytes in electric eels are ultra-thin biological cells, capable of generating over 600 volts of electricity in a brief burst,” Najem explained. “These cells achieve very high-power densities, meaning they can produce a lot of power from small volumes.”
The team constructed their power sources entirely from hydrogel to ensure the batteries remained non-toxic and flexible, even as they increased in power.
Applications and Advantages
For biomedical and near-biology applications, the compatibility of batteries with their surroundings is crucial. Najem emphasized the importance of developing power sources that are flexible, safe, and ideally capable of using available resources to recharge. This requirement motivated the team to create a robust power source within a hydrogel-based system, designed to operate well within biological environments.
Using a technique known as spin coating, which deposits ultra-thin layers of material on a rotating surface, the team layered four different hydrogel mixtures, each only 20 micrometers thick—a fraction of the width of a human hair. This thin geometry reduces internal resistance, essential for producing high power while maintaining mechanical strength and flexibility.
Potential Impact and Future Directions
The implications of this research are profound, particularly for the medical field. The ability to power devices within the human body safely and effectively could lead to significant advancements in medical technology and patient care. Moreover, the environmentally stable nature of these hydrogel-based batteries aligns with the growing demand for sustainable and eco-friendly technology solutions.
Looking ahead, the research team plans to explore further applications of their technology in various fields, including wearable electronics and soft robotics. By continuing to refine their designs and materials, they hope to unlock new possibilities for flexible, powerful, and safe energy sources.
This development follows a broader trend in bio-inspired engineering, where scientists look to nature for innovative solutions to complex technological challenges. As the field evolves, the lessons learned from electric eels may illuminate new paths in energy storage and generation.
