Design and fabrication of patterned flexible electrode using DC sputtering and shadow mask

Abstract

Flexible electrodes are essential components of flexible electronic devices. However, fabricating these electrodes is challenging because conventional methods are not easily applicable to them. Flexible substrates, such as polymer, fabric, and paper, are delicate and require specialized deposition techniques. To address this challenge, we present a novel, single-step method using DC sputtering and a shadow mask to fabricate high-resolution silver electrodes on polymer and fabric substrates. This approach is cost-effective, overcomes the limitations of multi-step processes, and enables direct electrode patterning. In our study, we produced and used thermoplastic polyurethane (TPU) with a thickness of 310 micrometers as the polymer substrate, which has an elongation at break of 749.39%. Furthermore, we demonstrate successful fabrication of silver electrodes on TPU with a sheet resistance of 3 (Ω/sq) and on wool fabric with 90 (Ω/sq) with a 10-micrometer resolution. In addition to the tensile test, we conducted a contact angle test to compare TPU characteristics with those of other common substrates. The result was 85.98° for TPU and 67.38° for metal-coated TPU. The findings indicate that this electrode showed high flexibility, bendability, and compatibility with curved surfaces, such as human hands, making it an excellent choice for wearable applications. This method is versatile and can be used for various substrates, materials, and patterns. Therefore, it can be useful for creating conductive paths and patterns on flexible substrates.