Direct wire writing technique benefitting the flexible electronics

This work proposes a rapid manufacturing technique for the conductive lines applied in flexible electronics, which is referred to as the 'direct wire writing (DWW)' technique. The fine metal wire is dragged out of the needle by adhesion, and attached to the stick-on substrate synchronously along design paths to form high-quality circuits. This technique overcomes the unstable performance of ink-based conductive lines fabricated by screen printing, spraying, 3D printing, etc., and avoids complex processes for stable metallic circuits mainly manufactured by the photolithography method, etc. Firstly, the forming mechanism of dominating the micro deformation behaviour (local-debonding, slip, warping) is clarified and analysed, which provides guidelines for fabricating in-plane wire patterns and 3D structural circuits rapidly and easily. Subsequently, some practical applications, including strain rosette, wearable sensor patch and light display are presented, showing the promising potential of the DWW technique in the ongoing exploration of flexible electronics.