柔軟な磁性導電性塗料の開発および回路プロトタイピングやセンシングへの応用

Recent advancements in flexible electronics have enabled rapid prototyping of circuits and sensors on deformable, nonplanar substrates such as paper, fabric, and human skin. Conductive paints and inks play a key role in these approaches; however, conventional materials often suffer from limited durability, unstable electrical contacts, and low flexibility in component placement, especially on soft substrates. In addition, sensing elements and wiring are typically fabricated from different materials, which increases structural complexity and limits design flexibility. In this study, I propose flexible magnetic conductive paints and magnetic conductive sheets that combine electrical conductivity, magnetic responsiveness, and mechanical flexibility in a single material. The proposed materials are fabricated by mixing metal powders, such as iron and copper, with soft base materials, allowing them to be applied by coating or molding onto a wide range of substrates. Owing to their magnetic properties, electronic components can be easily attached, detached, and repositioned using magnets, while the conductive properties enable the materials to function as electrical wiring and sensing elements. I experimentally evaluated the electrical and magnetic characteristics of the proposed materials, focusing on the effects of material composition, substrate type, and environmental conditions. For the magnetic conductive paint, a weight ratio of iron powder, copper powder, and liquid rubber of 2:3:5 provided a good balance between conductivity, magnetic responsiveness, and flexibility. In contrast, for the magnetic conductive sheet, a weight ratio of 1:1:2 achieved the most balanced performance. Furthermore, when the materials were applied with sufficient thickness, their electrical resistance changed in response to pressing and deformation, enabling their use as pressure and deformation sensors. To demonstrate practical applicability, I implemented several application examples, including circuit prototyping on paper, fabric, and skin, as well as a wearable device for measuring finger bending and recognizing hand movements. These results indicate that the proposed magnetic conductive materials provide a unified solution for wiring, component connection, and deformation-based sensing, and offer new possibilities for flexible input devices and deformable interaction systems.