Industrial Grade, Bending‐Insensitive, Transparent Nanoforce Touch Sensor via Enhanced Percolation Effect in a Hierarchical Nanocomposite Film

• Published in: Advanced functional materials Vol. 28; no. 42
• Main Authors: Yoo, Jae‐Young, Seo, Min‐Ho, Lee, Jae‐Shin, Choi, Kwang‐Wook, Jo, Min‐Seung, Yoon, Jun‐Bo
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 17.10.2018
• Subjects: Deformation; Electrodes; force touch sensors; Materials science; nanocomposite insulators; Nanocomposites; nanograting; Nanoparticles; Percolation; Radius of curvature; Sensitivity; Sensors; stress concentration; Touch
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201804721

Force touch sensors have received a great deal of attention for various applications owing to their versatile ability to detect touch and pressure. To demonstrate high‐performance force touch sensors, numerous studies have been performed, focusing on high sensitivity, transparency, and mechanical durability against bending. However, it is still challenging to apply force touch sensors in flexible applications, because their sensing performance is subject to change and degraded by induced mechanical stress and deformation when the device is bent. Here, a high‐performance and transparent nanoforce touch sensor with bending‐insensitivity is reported. This is achieved by developing a thin, flexible, and transparent hierarchical nanocomposite film, which is composed of a nanostructured plastic base, coplanar electrodes, and a dielectric polymer layer with silver nanoparticles. The fabrication process is simple that high manufacturing repeatability, uniformity, and reliability are achieved on a large‐area (8 in.) scale. The fabricated device shows a pressure sensitivity of 0.036 kPa−1 with high transparency (83%) in a pressure range up to 3 kPa. In particular, its thin thickness (45 µm) and the coplanar electrode enable to achieve excellent insensitivity to the bending with a radius of curvature of 4 mm more than 10 000 times. The bending‐insensitive and transparent nanoforce touch sensor with high sensitivity is proposed by developing hierarchical nanocomposite films, composed of large‐area (7 in.) 100 nm nanograting plastic bases and dielectric polymer layer with metal nanoparticles. In particular, the proposed sensor‐device successfully shows high‐performances meeting industrial‐grade requirements such as sensitivity, reliability, transparency, uniformity, and reproducibility, owing to its simple design and semiconductor‐based fabrication process.