STTR Phase I: Ultrasonic Nanocoining for Creating Large, Low-Cost Arrays of Sub-Wavelength Features

这项小型企业技术转移（STTR）第一阶段项目的广泛影响/商业潜力是大幅降低制造具有功能纳米级特征的大型表面的成本。其中一个例子是蛾眼结构，由200纳米宽、200纳米高的连续图案组成，具有表面抗反射特性。抗反射表面可以提高太阳能电池的效率，隐藏飞机或船只，或防止挡风玻璃或电脑屏幕上的眩光。纳米特性还可以通过自湿和防污特性，以及防雾或除冰特性，创造出具有卓越耐用性和清洁度的表面。这种低成本的大规模生产是通过“卷对卷”加工完成的，在这种加工中，一个涂有纳米特征的鼓形金属圆柱体被用作模具，用来滚动几英里长的薄膜，复制功能性涂层。这个项目的智力价值集中在准确和廉价地在金属鼓模上创建纳米级特征，用于卷对卷复制过程。这是通过最近开发的纳米铸造工艺完成的，利用金刚石模具将纳米特征压痕到金属表面，每秒压痕4万次。目前的加工方法依赖于用锋利的工具刮掉材料，不能创造纳米尺度的特征。这是因为任何足够锋利的工具来创造这样一个小的特征将是非常脆弱的，容易受到快速磨损。缩进从根本上来说是不同的，几千年来一直被用来制造硬币。没有材料被移除；它被简单地推到一边，在骰子上留下图案。摩擦的减少大大减少了磨损，并且没有去除材料的碎片，使该工艺能够在纳米尺度上工作。研究的初始阶段的目标是缩进一个小的测试鼓，并复制涂有金刚石模具特征的塑料薄膜。然后将测试该薄膜的抗反射和润湿性能，并在后期阶段进行放大。

The broader impact/commercial potential of this Small Business Technology Transfer (STTR) Phase 1 project is to drastically reduce the cost of creating large surfaces coated with functional nano-scale features. One example is the moth-eye structure, consisting of a continuous pattern of 200 nm wide by 200 nm tall features, that gives surface anti-reflective properties. An anti-reflective surface can increase efficiency of solar cells, conceal aircraft or ships, or prevent glare on windshield glass or computer screens. Nano-features can also be used to create surfaces with superior durability and cleanliness through self-wetting and anti-fouling characteristics, as well as anti-fogging or de-icing properties. The low-cost scale-up is done through "roll-to-roll" processing, where a drum-shaped metal cylinder coated with nano-features is used as the mold for rolling miles of thin film, replicating the functional coating. The intellectual merit of this project is focused on accurately and inexpensively creating nano-scale features on the metal drum mold that is used in the roll-to-roll replication process. This is done using the recently-developed nanocoining process, whereby nano-features are indented into a metal surface using a diamond die indent features into the surface 40,000 times per second. Current machining methods rely on scraping material away with a sharp tool and cannot create features on nano-scale. This is because any tool sharp enough to create such a small feature will be prohibitively fragile and susceptible to rapid wear. Indenting is fundamentally different, and has been used for millennia to create coins. No material is removed; it is simply pushed aside, leaving behind the pattern on the die. The reduction of rubbing drastically reduces wear and the absence of a chip of removed material enables the process to work on the nano-scale. The objective of the initial phase of research is to indent a small test drum and replicate a plastic film coated with the features from the diamond die. The film will then be tested for anti-reflective and wetting properties, and scale-up will follow in later phases.