Understanding and Leveraging the Effect of Nanoscale Roughness on Macroscale Adhesion

许多现代技术生产用于电子、通信、医药等应用的微型设备。这些设备的小尺寸导致其制造和使用的独特问题。然而，许多这些新兴的设备和制造技术面临着粘性或粘附性的问题。具体来说，当小尺寸的部件接触时，它们会自发地粘在一起，不容易被拉开。这个问题极大地限制了其他有前途的技术的性能和可靠性。这项拨款支持基础研究，以了解附着对表面粗糙度的依赖。这个项目将开发测量小尺寸粗糙度的新方法，以及控制它的新方法。最终，从这项调查中获得的见解将使在制造过程中有意修改粗糙度以提高最终设备的性能。这项调查是由一个国际研究小组进行的，并纳入了具体的教育计划，既针对工业工程师，将研究付诸实践，也针对小学生，以增加下一代美国工程师的兴趣和参与。该奖项的目标是：(1)确定对附着力影响最大的表面粗糙度的长度尺度；(2)制定制造策略，合理修改这些尺度上的形貌以控制附着力。首先，研究将使用透射电子显微镜来表征先前未测量的技术相关材料上的地形尺度，然后使用定制的微机械测试仪来测量它们的表面附着力。实验结果将在现有的分析和数值模型的背景下进行分析，以评估和改进这些模型。为了获得有关材料响应的原子尺度信息，实验将辅以对相同表面的大规模计算机模拟。模拟将通过与德国卡尔斯鲁厄理工学院（Karlsruhe Institute of Technology）的非nsf资助的强大合作来进行。其次，使用先进的光刻技术，测试表面的小尺度粗糙度将系统地变化，并定量地与性能变化联系起来。这将使粗糙表面模型的实验测试以及修改表面粗糙度以实现最佳表面附着力的途径的演示成为可能。这项研究将对微型设备和先进制造产生直接影响，这两者都需要精确理解和控制表面性质。此外，粗糙度模型的实验验证将更广泛地应用于粗糙表面，从汽车部件到路面再到医疗植入物。

Many of the modern technologies produce miniaturized devices used in applications from electronics, communications, medicine as well as others. The small size of these devices leads to unique issues in their manufacture and use. However, many of these emerging devices and manufacturing techniques face a problem with stickiness or adhesion. Specifically, when small-size parts come into contact, they spontaneously stick together and cannot easily be pulled apart. This problem significantly limits the performance and reliability of otherwise promising technologies. This grant supports fundamental research to understand the dependence of adhesion on surface roughness. This project will develop new ways to measure roughness at small sizes, and also new ways to control it. Ultimately, the insights gained from this investigation will enable the intentional modification of roughness during manufacturing to improve the performance of the final devices. The investigation is being conducted by an international team of researchers, and incorporates specific programs for education both for engineers in industry to put the research into practice, and also for grade-school students to increase interest and participation among the next generation of American engineers. The goals of this award are: (1) to identify the length scales of surface roughness that most strongly impact adhesion; and (2) to develop fabrication strategies to rationally modify topography at these scales to control adhesion. First, the investigation will use transmission electron microscopy to characterize previously unmeasured scales of topography on technologically-relevant materials, and then use a custom micromechanical tester to measure their surface adhesion. Experimental results will be analyzed in the context of existing analytical and numerical models, in order to evaluate and then improve these models. The experiments will be complemented by large-scale computer simulations of identical surfaces, in order to gain atomic-scale information about the material response. The simulations will be carried out through a strong non-NSF-funded collaboration with the Karlsruhe Institute of Technology in Germany. Second, using advanced lithographic techniques, the small-scale roughness of test surfaces will be systematically varied and quantitatively linked to changes in properties. This will enable both experimental tests of rough-surface models, as well as the demonstration of routes to modify surface roughness to achieve an optimal surface adhesion. This investigation will have direct impact on microscale devices and on advanced manufacturing, both of which require precise understanding and control of surface properties. Further, the experimental validation of roughness models will have application to rough surfaces more broadly from automotive components to road surfaces to medical implants.