A research team from the Dalian University of Technology has developed an alternative 3D printing method for electrically conductive microstructures, particularly suited for flexible electronics applications. Instead of relying on traditional nozzle-based extrusion, the process uses a tension-driven fluid-drawing technique. The study was published on May 12, 2025, in the journal Microsystems & Nanoengineering.
At the core of this method is a high-viscosity silver nanoparticle ink, which is stretched into mid-air filaments by a single needle. The ink forms a stable liquid bridge between the needle and the substrate, narrowing into a wire as the needle is lifted and solidifying in real time through rapid solvent evaporation. This approach enables the creation of structures with diameters below ten micrometers—down to as little as 4 μm, which is smaller than the nozzle’s physical diameter.
The technique allows for precise control over wire geometry by adjusting parameters such as lifting speed, ambient temperature, and air pressure. A subsequent thermal post-treatment reduces the electrical resistivity of the printed traces to around 2.5 × 10⁻⁷ Ω·m—approaching the conductivity of bulk silver. The delicate wire structures withstood over 200 bending cycles without significant performance degradation.
Demonstration devices fabricated with this technique include addressable LED arrays, thermal imaging sensors on mica substrates, and oscillator circuits. All were printed on single-layer substrates, eliminating the need for multilayer PCB construction and via drilling. This can lead to increased component density and reduced production complexity.
“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.”
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