Abstract
Abstract We presented a novel, maskless approach for fabricating copper electrodes on flexible polyimide substrates using direct laser metallization (DLM) from deep eutectic solvents (DES). The DLM process utilizes localized thermochemical reactions driven by a picosecond pulsed laser to convert DES precursors into conductive copper structures with precise patterning. Key parameters such as laser power density, scanning speed, and DES layer thickness were optimized to achieve uniform copper lines with excellent electrical conductivity and mechanical flexibility. The fabricated electrodes demonstrated remarkable stability under bending tests, showing less than 5% variation in resistance, which confirms their suitability for flexible pressure and strain sensor applications in wearable electronics and human–machine interfaces. This is the first demonstration of copper structures produced on polyimide via DES-based DLM with proven functional performance, highlighting its potential as a scalable, cost-effective method for next-generation flexible electronic device manufacturing.