Researchers have created an innovative method for constructing intricate 3D microfluidic networks by using molds made from plant roots and fungal hyphae. The team cultivated plants and fungi within silica nanoparticles and then removed the plants, leaving behind solid glass with tiny networks where the roots once grew.
Microfluidic technology is increasingly essential in various scientific areas, including regenerative medicine, microelectronics, and environmental science. Nevertheless, traditional microfabrication methods encounter challenges regarding scale and the creation of complex networks. These challenges become even greater when trying to produce sophisticated 3D microfluidic networks.
Researchers at Kyushu University have introduced a simple and effective technique for constructing such complex 3D microfluidic networks. Their inspiration? Plants and fungi. By formulating a ‘soil’ medium using silica nanoparticles and a cellulose-based binder, the researchers encouraged plants and fungi to grow their roots into this medium. Once the plants were extracted, the resulting glass structure revealed a detailed 3D microfluidic network filled with micrometer-sized voids where the roots had been.
This innovative method also facilitates the examination and preservation of 3D biological structures that are often challenging to study in traditional soil environments, opening new avenues for research in plant and fungal biology. Their results were published in the journal Scientific Reports.
“Our main goal was to eliminate the restrictions of standard microfabrication methods when creating complex 3D microfluidic configurations,” says Professor Fujio Tsumori from the Faculty of Engineering at Kyushu University, who led the project. “Our lab focuses on biomimetics, where we seek solutions to engineering challenges by observing and mimicking nature’s designs.” He further notes, “What better illustration of microfluidics in nature exists than plant roots and fungal hyphae? Therefore, we aimed to develop a method that leverages the natural growth patterns of these organisms to form optimized microfluidic networks.”
The researchers initially produced a ‘soil’ mixture for plant growth. This blend included glass nanoparticles smaller than 1 μm in diameter, combined with hydroxypropyl methyl cellulose as a binding agent, rather than traditional soil. They then planted seeds in this unique medium and monitored the growth. After ensuring the plants thrived, they baked the mixture, leaving behind glass transformed by the root structures.
“This procedure is termed sintering, a process that compacts fine particles into a more solid form, similar to powder metallurgy used in ceramics manufacturing,” explains Tsumori. “In this instance, the plant serves as the mold.”
This innovative approach successfully recreated the complex structures found in a plant’s primary roots, reaching sizes of up to 150 μm in diameter, down to root hairs measuring about 8 μm in diameter. Experiments with different organisms indicated that this method could also reproduce the root structures of fungi, known as hyphae.
“Hyphae can be even finer than that, with diameters as small as 1-2 μm, which is thinner than a single strand of spider silk,” Tsumori adds.
The research team anticipates that their bio-inspired microfluidic fabrication technique could be applied across various scientific and engineering fields, potentially resulting in more efficient microreactors, advanced heat exchangers, and novel scaffolds for tissue engineering.
“In biological sciences, this approach offers a novel tool for investigating the intricate 3D structures of plant roots and fungal networks, thereby enhancing our understanding of soil ecosystems,” Tsumori concludes. “By linking biological systems with engineering, our research could lead to new technologies and groundbreaking scientific insights.”
