Department of Smart Manufacturing Engineering, Changwon National University, Changwon, South Korea.
Department of Flexible & Printed Electronics, Korea Institute of Machinery and Materials, Daejeon, South Korea.
Nat Commun. 2023 Apr 18;14(1):2202. doi: 10.1038/s41467-023-37828-8.
The main challenge in preparing a flexible mold stamp using roll-to-roll nanoimprint lithography is to simultaneously increase the imprintable area with a minimized perceptible seam. However, the current methods for stitching multiple small molds to fabricate large-area molds and functional surfaces typically rely on the alignment mark, which inevitably produces a clear alignment mark and stitched seam. In this study, we propose a mark-less alignment by the pattern itself method inspired by moiré technique, which uses the Fourier spectral analysis of moiré patterns formed by superposed identical patterns for alignment. This method is capable of fabricating scalable functional surfaces and imprint molds with quasi-seamless and alignment mark-free patterning. By harnessing the rotational invariance property in the Fourier transform, our approach is confirmed to be a simple and efficient method for extracting the rotational and translational offsets in overlapped periodic or nonperiodic patterns with a minimized stitched region, thereby allowing for the large-area and quasi-seamless fabrication of imprinting molds and functional surfaces, such as liquid-repellent film and micro-optical sheets, that surpass the conventional alignment and stitching limits and potentially expand their application in producing large-area metasurfaces.
使用卷对卷纳米压印光刻技术制备柔性模具印章的主要挑战是在最小化可感知接缝的同时增加可压印面积。然而，目前将多个小模具拼接以制造大面积模具和功能表面的方法通常依赖于对准标记，这不可避免地会产生明显的对准标记和拼接接缝。在这项研究中，我们受莫尔技术启发，提出了一种无需标记的对准方法，该方法利用通过叠加相同图案形成的莫尔图案的傅里叶光谱分析进行对准。该方法能够制造具有准无缝和无对准标记图案的可扩展功能表面和压印模具。通过利用傅里叶变换中的旋转不变性特性，我们的方法被证实是一种简单有效的方法，用于提取重叠周期性或非周期性图案中的旋转和平移偏移，从而允许大面积和准无缝制造压印模具和功能表面，例如，疏液膜和微光学片，这些都超过了传统对准和拼接限制，并有可能扩展它们在制造大面积超表面方面的应用。
