In a groundbreaking advancement poised to revolutionize the field of flexible energy harvesting, researchers have unveiled a novel class of hydrovoltaic cells characterized by exceptional stretchability and durability. The study, conducted by a team led by W. Son, J.M. Lee, and H. Seo, introduces fully stretchable hydrovoltaic cells constructed using winding-locked double-helical carbon nanotube fibers. This pioneering design not only elevates the performance parameters of hydrovoltaic devices but also addresses critical challenges associated with flexibility, mechanical resilience, and efficiency, marking a significant leap forward in wearable and flexible electronics.
Hydrovoltaic technology, which exploits the interaction between water and nanostructured materials to generate electricity, has emerged as a promising approach to sustainable energy harvesting. Conventional hydrovoltaic devices typically encounter limitations due to their rigid structures or insufficient mechanical compliance, hindering their integration into flexible systems such as wearable electronics or stretchable sensors. The researchers’ innovative use of double-helical carbon nanotube fibers functions as both a nanoscale conductive element and a mechanically robust architecture capable of enduring substantial deformation without compromising electrical performance.
The concept of winding-locking in the double-helix configuration plays a pivotal role in this innovation. Carbon nanotubes, well-known for their exceptional electrical conductivity and mechanical strength, are entwined in a specific manner that imparts both flexibility and structural stability to the fiber composite. The winding-locked arrangement prevents slippage between the strands, allowing the fiber to maintain consistent electrical pathways even under large strains. This mechanically resilient design ensures the device’s operational stability when subjected to the kinds of stretches and bends encountered in everyday wearable applications.
One of the critical technical achievements of this research is the precise control over the diameter, pitch, and winding angle of the double-helical fibers. By optimizing these parameters, the researchers enhanced the contact area between the fiber surface and water molecules, thereby improving hydrovoltaic energy conversion efficiency. The surface morphology and chemical composition were meticulously engineered to facilitate efficient ion adsorption and electron flow, harnessing the synergy between the nanostructured carbon materials and water interaction.
In addition to structural innovations, the team integrated surface functionalization strategies to augment the fibers’ hydrophilicity and charge density. Such tailoring of surface properties ensures a stable and amplified electrochemical response when exposed to moisture or water droplets, a crucial factor for practical energy harvesting under ambient humidity conditions. This enhancement directly translates into higher voltage and current outputs compared to previously reported hydrovoltaic devices made from conventional materials.
The devices demonstrated remarkable stretchability, withstanding tensile strains exceeding 100% while retaining over 90% of their initial electrical output. This robustness was validated through rigorous cyclic stretching tests, where the hydrovoltaic cells maintained consistent open-circuit voltage and short-circuit current over thousands of deformation cycles. This durability confirms the potential of these cells for long-term use in flexible electronics, where repeated mechanical stresses are inevitable.
In practical demonstrations, the hydrovoltaic cells efficiently harvested energy from various water sources, including sweat droplets, rainwater, and ambient humidity, highlighting their versatility. Such adaptability paves the way for self-powered wearable devices capable of continuous operation without reliance on conventional power sources. The integration of these cells into textiles and elastic substrates opens exciting possibilities for smart clothing and health-monitoring patches that can autonomously generate power from body moisture.
Furthermore, the team explored the scalability of their manufacturing approach. Using a combination of chemical vapor deposition and precise mechanical winding techniques, they produced carbon nanotube fibers in sufficient lengths and quantities suitable for commercial applications. The scalability ensures that this technology can transition beyond the laboratory, fostering the development of next-generation energy systems that combine sustainability and user convenience.
This research not only broadens the horizons of hydrovoltaic cell technology but also sheds light on the broader implications of nanomaterial structuring for energy device design. The double-helical carbon nanotube fiber architecture can inspire advancements across different domains where mechanical flexibility and electronic functionality must coalesce, including flexible photovoltaics, triboelectric nanogenerators, and stretchable sensors.
Moreover, the interplay between mechanical engineering and electrochemical performance observed in the winding-locked double helices reveals new pathways for optimizing the interface between soft matter and electronic materials. This interdisciplinary approach underscores the importance of multidisciplinary collaboration integrating materials science, nanotechnology, and applied physics to address complex challenges in energy harvesting.
The potential impact on wearable technology is especially noteworthy. As consumer demand grows for devices that seamlessly integrate with daily life, energy autonomy becomes crucial. These fully stretchable hydrovoltaic cells stand out as a viable solution for powering a diversity of low-energy electronics, reducing the need for frequent battery replacements and enabling more sustainable device ecosystems.
Looking toward future directions, the integration of these double-helical carbon nanotube fibers with complementary energy storage elements such as supercapacitors or microbatteries could yield fully integrated self-sustaining systems. Such hybrid configurations might enhance energy density and supply stability, addressing one of the remaining hurdles in the broader adoption of flexible energy technologies.
Overall, the research encapsulates a forward-thinking approach to energy harvesting challenges, turning nanomaterial intricacies into macroscopic advantages. As flexible and wearable technology matures, innovations like the winding-locked double-helical fibers promise to underpin a new era where devices are as adaptable as the human body itself, powered sustainably by ubiquitous environmental resources such as water.
This transformative advancement positions the scientific community closer to a future where energy-harvesting systems can be seamlessly embedded into everyday textiles and accessories, fostering an era of connectivity and sustainability without compromising comfort or style. With ongoing research and development, fully stretchable hydrovoltaic devices could soon become a cornerstone technology in the rapidly evolving landscape of flexible electronics.
Subject of Research: Development of fully stretchable hydrovoltaic cells using winding-locked double-helical carbon nanotube fibers.
Article Title: Fully stretchable hydrovoltaic cells based on winding-locked double-helical carbon nanotube fibers.
Article References:
Son, W., Lee, J.M., Seo, H. et al. Fully stretchable hydrovoltaic cells based on winding-locked double-helical carbon nanotube fibers. npj Flex Electron 9, 116 (2025). https://doi.org/10.1038/s41528-025-00493-6
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