The 3D printing method pulls ink threads to make circuits. It is simple, fast, and useful for smart and wearable devices.
Researchers at Dalian University of Technology have developed a new 3D printing method called tension-driven fluid drawing. Unlike traditional liquid-based 3D printing, which pushes ink through a nozzle, this method pulls ink out like a thread. A silver nanoparticle ink is heated to form a small liquid bridge between the needle and the surface. As the needle lifts, the ink stretches into fine, three-dimensional structures—some as thin as 4 micrometers, even thinner than the needle itself.
The entire process uses only one needle to draw the circuit in 3D, removing the need for stacking multiple layers or drilling vias. This single-step approach simplifies how flexible circuits are made. The printed structures are conductive and flexible, capable of withstanding repeated bending.
Because the ink is drawn rather than extruded, the method offers better control over the structure, speed, and size of the printed lines. The combination of air pressure, thermal evaporation, and optimized ink viscosity allows precise shaping of circuits on flat and curved surfaces.
The printed circuits remain conductive after at least 200 bending cycles, showing strong durability. The team also demonstrated the method’s flexibility by creating a range of working circuits: LED arrays, heatable designs visible through thermal imaging, and a flexible self-oscillating circuit.
This method has potential uses in wearable medical sensors that conform to the body, stretchable displays, and ultra-compact IoT devices. Since it avoids complex steps like multi-layering and drilling, it could speed up production and reduce manufacturing costs.
By rethinking how circuits are built in three dimensions, this technique supports faster, simpler, and more adaptable electronics manufacturing—especially for small, flexible, and body-integrated devices.
