Flexible electronics are central to emerging technologies like wearable devices, foldable displays, and soft robotics. However, traditional printed circuits rely on planar designs and layered manufacturing, which can't keep pace with rising demands for complexity, compactness, and mechanical flexibility. Existing three-dimensional (3D) printing methods often sacrifice either resolution or speed, limited by ink viscosity and nozzle geometry. Furthermore, maintaining electrical conductivity and structural integrity during bending remains a persistent challenge. Due to these problems, new strategies are needed to directly and reliably fabricate freestanding, conductive architectures that combine miniaturization with mechanical resilience.
In a study (DOI: 10.1038/s41378-025-00936-0) published on May 12, 2025, in Microsystems & Nanoengineering, a team from Dalian University of Technology unveiled a tension-driven fluid drawing technique for printing freestanding 3D conductive wires. Using a high-viscosity silver nanoparticle ink, a single-needle setup stretches ink into mid-air filaments while solvent evaporation solidifies the wire in real time. This method bypasses the constraints of nozzle-diameter-limited extrusion and achieves sub-10 μm resolution. The team demonstrated this approach in flexible electronic prototypes ranging from light-emitting diode (LED) grids to thermal imaging devices, showcasing a promising shift in circuit design.
Instead of pushing ink through a nozzle, this technique draws it like a thread, exploiting the interplay of air pressure, ink viscosity, and thermal evaporation. Silver nanoparticle ink is carefully formulated to thicken upon heating, forming a stable “liquid bridge” between needle and substrate. As the needle lifts, the ink stretches into narrow filaments that solidify instantly, allowing wire widths as fine as 4 μm—thinner than the nozzle itself. Adjusting speed and air pressure tunes wire thickness and length. Post-print thermal treatment boosts conductivity, reducing resistivity to near-bulk silver levels (2.5 × 10⁻⁷ Ω·m). The printed wires remained intact and conductive after 200 bending cycles. Circuit demonstrations include LED arrays with vertical and horizontal addressability, thermal imaging units on mica sheets, and self-oscillating multivibrator circuits—all fabricated with a single-layer print. These freestanding connections replace multi-layer boards, simplifying both architecture and assembly while maintaining excellent electrical and mechanical performance.
“This work challenges the status quo in flexible circuit manufacturing,” said Dr. Dazhi Wang, co-corresponding author of the paper. “By drawing the ink rather than extruding it, we gain unprecedented control over structure, speed, and size—all from a single needle. It's not just a printing method—it's a rethinking of how we build circuits in three dimensions. The implications for wearable tech and soft robotics are profound.”
The fluid drawing method offers a powerful tool for next-generation circuit design, particularly in flexible and wearable electronics. Its high precision and mechanical durability make it suitable for applications where conventional printing fails—such as conformable medical sensors, stretchable light displays, and compact IoT devices. Because it eliminates the need for multilayer routing and via-hole drilling, it can reduce production time and costs while improving customization. Looking forward, this approach may influence the broader field of additive manufacturing by inspiring ink innovations and thermal design strategies to support even more materials and substrates.
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References
DOI
10.1038/s41378-025-00936-0
Original Source URL
https://doi.org/10.1038/s41378-025-00936-0
Funding information
This research was supported by the National Natural Science Foundation of China (Grant No. U24A20137, 52475587, 52103224, 52405610), Science and Technology Program of Liaoning Province (2023JH1/10400044), Natural Science Foundation of Ningbo Municipality (2022J008), Fundamental Research Funds for the Central Universities (DUT23RC(3)051, DUT24RC(3)048).
About Microsystems & Nanoengineering
Microsystems & Nanoengineering is an online-only, open access international journal devoted to publishing original research results and reviews on all aspects of Micro and Nano Electro Mechanical Systems from fundamental to applied research. The journal is published by Springer Nature in partnership with the Aerospace Information Research Institute, Chinese Academy of Sciences, supported by the State Key Laboratory of Transducer Technology.