Rapid fabrication of flexible copper-plated circuit boards on cotton fabrics and conductive threads for textile materials using pencil-drawn technique

This study presents an approach for fabricating flexible and stable electroplated circuits directly onto fabric and thread. We achieve this through a simple method. Pencil-drawn patterns on cotton fabric are followed by copper electroplating in a copper sulfate solution. This method eliminates the need for complex pre-treatment and lithography techniques, thus enabling rapid and on-site circuit development. This research investigated the influence of different pencil grades, drawing frequency, and plating time on the overall conductivity and flexibility of the fabric-based circuits. The electroplated copper demonstrated exceptional bending and thermal stability, maintaining consistent conductivity over a wide bending range (-180° to 180°), with minimal linear resistance change after extreme twisting. Furthermore, the fabricated circuits functioned effectively as Light Dependent Resistor (LDR) based Plated Circuit Boards (PCB), demonstrating robustness and practical potential. The fabrication of conductive threads has also been explored by electroplating graphite threads. These threads displayed remarkable flexibility, maintaining consistent conductivity (0.5 Ω/cm) even under tight knots. The copper-plated textile exhibited stable resistance: 0.6 Ω across 22 °C to 55 °C and 0.5 Ω/cm under bending angles from -180° to +180°. It endured 1000 folding cycles, with resistance increasing slightly to 1.3 Ω. Furthermore, this work shows that the flexible PCBs are resistant to folding stress, environmentally friendly, and disposable, which is a significant step toward sustainable electronics. The results of this study hold significant potential applications in textile-based electrical systems, wearable electronics, and sensors.