Reviewed by Lexie CornerMar 26 2025
A research team at the University of Turku in Finland has developed a new method for replicating bioinspired microstructures found in plant leaf skeletons, eliminating the need for traditional cleanroom technologies.
A pressure sensor made from the surfaces mimicking the fractal structure of a leaf was directly mounted onto the fingertip of a robotic hand using encapsulation tape. This electronic skin allowed the robotic finger to sense touch, as the pressure sensor reacts to contact. This technology can also be used in prosthetic limb movement detection and human motion detection. Image Credit: Timo Laukkanen
Fractal patterns are self-replicating structures where the same shape repeats at progressively smaller scales. These patterns, which can be generated mathematically, are commonly found in nature, such as in floral structures, vascular networks, leaf veins, and tree branches.
In this study, researchers used dried tree leaf skeletons to create surfaces that mimic fractal patterns. Various materials were sprayed onto the leaf skeletons, and the resulting surfaces were separated and analyzed. The researchers compared the structural properties and durability of surfaces made from different materials.
The biomimetic surfaces demonstrated more than 90 % replication accuracy, offering superior breathability, conformal skin attachment, and increased stretchability, making them ideal for flexible electronic applications. These fractal-patterned surfaces maximize surface area while maintaining mechanical flexibility, which enhances electrical conductivity, energy efficiency, energy dissipation, and charge transport in electronic materials.
These surfaces are well-suited for next-generation flexible electronics such as wearable sensors, transparent electrodes, and bioelectronic skin, as they ensure longevity and excellent performance under mechanical stress.
Compared to artificial fractals like those created with origami or kirigami, leaf skeleton fractals provide naturally optimized, hierarchical, and scalable structures. They have a high surface-area-to-volume ratio, offering exceptional flexibility, breathability, and transparency.
While leaf skeletons offer excellent fractal structures, they are not naturally stretchable, durable, or scalable. By using leaf skeletons as templates and replicating their patterns with stretchable and durable polymers, researchers were able to create surfaces with improved flexibility and longevity, facilitating large-scale production.
We have succeeded in merging nature’s efficient designs with modern materials, which opens new possibilities for flexible and wearable electronics.
Amit Barua, Doctoral Researcher, University of Turku
Reducing Environmental Impact
Researchers applied a thin layer of metal nanowires to the biomimetic surfaces, making them conductive, with a surface resistivity of about 20 Ω. These conductive surfaces were then integrated into various applications, such as electronic skin devices, heating systems, and tactile sensing.
This new biomimetic technique, which uses less energy and is adaptable to environments outside of controlled settings, offers an environmentally friendlier alternative to conventional cleanroom-based methods. Additionally, sustainable polymers can be used in the process to further reduce its environmental impact.
Master collectors, combined with finite element method (FEM) simulations and computer-aided design (CAD) models, can be used to replicate biotic designs for large-scale production. Moreover, depending on the specific requirements of the device, more environmentally friendly conductive materials can replace silver nanowires.
To design sophisticated microstructures with high precision, cleanroom fabrication is usually required. This new biomimetic approach has the potential to bypass the need for cleanroom technologies when fabricating complex architectures, thereby contributing to lower carbon emissions.
Amit Barua, Doctoral Researcher, University of Turku
Amit Barua is a member of the Materials for Flexible Devices research group at the University of Turku's Department of Mechanical and Materials Engineering. The team is led by Assistant Professor Vipul Sharma.
Journal Reference:
Barua, A., et al. (2025) Biomimetic freestanding microfractals for flexible electronics. npj Flexible Electronics. doi.org/10.1038/s41528-025-00381-z.