Signal Modulation of a 3D Printer for Direct Laser Patterning of Durable and Reusable Copper Electrodes

A low‐cost, high‐performance laser direct patterning (LDP) technique is demonstrated by modifying a commercial 3D printer to enable high‐frequency laser modulation up to 100 kHz. By intercepting the printer's internal laser signal and replacing it with a user‐defined source, the limitation of standard systems is overcome. Under optimized conditions (50 kHz, 15 mm s ⁻¹ ), the process achieves copper resistivities as low as 5.1 μΩ·cm—comparable to or exceeding conventional LDP results. High‐frequency modulation not only improves electrical conductivity but also reduces patterning defects, lowers energy consumption (from 0.1 to 0.043 μJ cm ⁻² ), and increases processing speed by up to 3.8 times. This method is applied to pattern copper on polyimide (PI) films for flexible electrode applications. Bending tests revealed that samples patterned at 50 kHz exhibited better mechanical durability than those at 0.5 kHz. Transfer tests showed stable sheet resistance even after cyclic transfers between PI/glass and PI/polypropylene substrates, indicating potential for reuse in soft electronics. Adhesion tests with commercial tapes demonstrated minimal resistance change after six cycles, confirming strong bonding of copper to PI. Overall, this approach offers a practical, scalable strategy for fabricating reliable, reusable soft electronic devices.