Manufacturing USA: High-Resolution Flexography for Printed Electronics Using Nanoporous Carbon Nanotube Stamps

几个世纪以来，印刷技术的创新与通信、教育和工业化的进步齐头并进。尽管数字媒体已经取代了印刷媒体的很大一部分，但印刷技术的进一步突破对于以新格式（例如，在窗户、隐形眼镜和产品包装上）可扩展地制造电子设备是必不可少的。然而，无法以高吞吐量打印具有微米级分辨率的电子材料是实现印刷电子的主要障碍。该奖项支持研究，以推进新的印刷工艺，作为低成本印刷设备的最先进的制造平台。最近发明的使用纳米多孔印模的印刷工艺可以在工业规模的印刷速度（大于0.1米每秒）下产生具有微米级横向尺寸（小于10微米）、精细边缘粗糙度（小于1微米）和小于100纳米范围内的高度均匀厚度的特征。印刷电子技术进步的实际意义以及该主题与行业合作伙伴和NextFlex柔性混合电子制造创新研究所的相关性，为印刷电子基础研究向商业市场的过渡提供了一条途径。因此，这项活动直接促进了国家的繁荣和安全。此外，该项目不仅强调对研究生和本科生的指导和推广，而且通过使用艺术图像推广纳米材料等举措，以及为制造工艺基础的大规模开放在线课程（MOOC）提供新的纳米制造教学模块，面向广大受众。新的打印工艺使用由聚合物涂层碳纳米管（CNT）森林组成的工程纳米多孔邮票，其是高度多孔的（90%），将油墨保持在其体积内而不是仅在其表面上，并且可以在机械接触下转移高度均匀的油墨层。 该项目侧重于以下三个主要领域：（1）通过分析和实验相结合的方法，研究油墨转移机理和精密过程控制;（2）卷对卷印刷和可靠性研究，其中在辊上制作纳米多孔印模，并使用台式设备研究高速卷对卷印刷;以及（3）利用纳米多孔柔性版印刷工艺的独特能力，即用于成像光谱仪的量子点（QD）滤波器、高分辨率薄膜晶体管和光学超颖表面的三种高价值应用的印刷器件的演示。 从这些努力中获得的理解使印刷特征的横向和垂直尺寸能够得到精确控制，并且可扩展的纳米多孔印模材料能够抵抗机械降解和印刷质量的损失。该奖项反映了NSF的法定使命，并且通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

For centuries, innovations in printing technologies have gone hand-in-hand with advances in communication, education, and industrialization. Even though digital media has replaced a significant fraction of print media, further breakthroughs in printing technologies are now essential for scalable manufacturing of electronic devices in new formats, for example, on windows, contact lenses, and product packaging. However, the inability to print electronic materials with micron-scale resolution at high throughput is a major roadblock to realizing printed electronics. This award supports research to advance a new printing process as a state-of-art manufacturing platform for low-cost printed devices. The recently invented printing process, which uses nanoporous stamps, can produce features with micron-scale lateral dimensions (less than 10 micrometers), fine-edge roughness (less than 1 micrometer) and highly uniform thickness in the less than 100 nanometer range, at industrial scale printing speeds (greater than 0.1 meter per second). The practical significance of advances in printed electronics and the relevance of this topic to industry partners and the NextFlex Flexible Hybrid Electronics Manufacturing Innovation Institute suggest a pathway for transition of fundamental research in printed electronics to the commercial marketplace. Therefore, this activity directly enhances the nation's prosperity and security. In addition, the project emphasizes mentorship and outreach not only to graduate and undergraduate students in research, but to broad audiences through initiatives such as promotion of nanomaterials using artistic imagery, and a new nanomanufacturing teaching module for a Massive Open Online Course (MOOC) on Fundamentals of Manufacturing Processes.The new printing process uses engineered nanoporous stamps composed of polymer coated carbon nanotube (CNT) forests, which are highly porous (90 percent), retain the ink within their volume rather than on their surfaces only, and can transfer highly uniform ink layers under mechanical contact. The project focuses on the following three main thrust areas: (1) investigation of the ink transfer mechanics and precision process control, by combination of analytical and experimental approaches; (2) roll-to-roll printing and reliability studies, wherein the nanoporous stamps are fabricated on rollers and high-speed roll-to-roll printing is studied using a desktop apparatus; and (3) demonstration of printed devices for three high-value applications that leverage the unique capabilities of nanoporous flexography process, namely quantum dot (QD) filters for imaging spectrometers, high-resolution thin-film transistors, and optical metasurfaces. Understanding from these efforts enable precision control of lateral and vertical dimensions of printed features, and scalable nanoporous stamp materials that resist both mechanical degradation and loss of print quality.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.