| Abstract Scope |
Printing flexible circuits remains immature and suffers from limitations like poor printability, frequent nozzle clogging, and low scalability. To address these issues, we present an ultrasound assisted direct‐ink-writing system that can continuously print multimaterials for customizable flexible circuits. To mitigate the blockage issue, the system was integrated with an ultrasonic actuator whose resonant vibration reduces ink viscosity for continuous extrusion. As a showcase, this system extrudes photoactive silicone resin reinforced with SiO₂ nanoparticles followed by real-time UV-curing into flexible silicone structures. Subsequently, sodium alginate encapsulated liquid metal was printed on the silicone substrates as electrically conductive traces, which show high electrical conductivity even after 1,000 bending and stretching cycles. Using these two materials, we demonstrated the versatility of this platform in fabricating a wireless charging pad, a crossbar LED array, and a flexible circuit for interactive augmented reality, showing its potential for rapid prototyping of soft, customizable electronics. |