A fast first-principles approach to model atomic force microscopy on soft, adhesive, and viscoelastic surfaces
A fast first-principles approach to model atomic force microscopy on soft, adhesive, and viscoelastic surfaces
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DOI：
10.1088/2053-1591/ac1fb7
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发表时间：
2021-09-01
影响因子：
2.3
通讯作者：
Raman, Arvind
中科院分区：
文献类型：
--
作者：
Rajabifar, Bahram;Wagner, Ryan;Raman, Arvind
定量原子力显微镜（AFM）对软聚合物仍然具有挑战性，由于缺乏易于使用的计算模型，准确地捕捉针尖和粘性，粘弹性样品之间的相互作用的物理。在这项工作中，我们增强了阿塔德的连续力学为基础的模型，可以说是最严格的接触模型的粘性粘弹性样品，通过三个关键的使能策略。首先，原始模型的形式主义重新安排，使模型的常微分方程（ODE）的快速和明确的解决方案。其次，变形的表面重建使用一套完整的优化正交基函数，而不是阿塔德的原始的，计算昂贵的径向离散。第三，使用多步数值方法求解模型的控制常微分方程，以进一步稳定用于软样本和粘性样本时的解。实施这些增强功能后，增强型阿塔德模型（EAM）更稳定，速度快3个数量级以上，与原始模型相比同样准确。这些促进EAM的列入到各种AFM操作模式的模拟。我们展示了基于EAM的模拟准静态力谱和调幅AFM的方法曲线上的软粘性聚合物表面。在一台典型的台式计算机上，与原始阿塔德模型的近似15小时相比，用EAM模拟调幅接近曲线需要不到一分钟。我们希望EAM是感兴趣的AFM社区，因为它有利于包括严格的模型尖端样品接触在模拟聚合物样品。EAM是部署在nanoHUB.org网络基础设施上的VEDA模拟工具集的一部分。
Quantitative atomic force microscopy (AFM) on soft polymers remains challenging due to the lack of easy-to-use computational models that accurately capture the physics of the interaction between the tip and sticky, viscoelastic samples. In this work, we enhance Attard's continuum mechanics-based model, arguably the most rigorous contact model for adhesive viscoelastic samples, via three key enabling strategies. First, the original model's formalism is rearranged to enable a fast and explicit solution of the model's ordinary differential equations (ODEs). Second, the deformed surface is reconstructed using a complete set of optimized orthogonal basis functions as opposed to Attard's original, computationally expensive radial discretization. Third, the model's governing ODEs are solved using a multi-step numerical method to further stabilize the solution when using for soft and sticky samples. Implementing these enhancements, enhanced Attard's model (EAM) is more stable, 3+ orders of magnitude faster, and equally accurate when compared to the original model. These facilitate EAM's inclusion into simulations of various AFM operating modes. We demonstrate EAM based simulations of quasi-static force spectroscopy and amplitude modulation AFM approach curves on soft sticky polymer surfaces. On a typical desktop computer, simulation of an amplitude modulation approach curve with EAM takes less than a minute as compared to approximate to 15 h by the original Attard's model. We expect EAM to be of interest to the AFM community because it facilitates the inclusion of rigorous models of tip-sample contact in simulations on polymer samples. EAM is available as part of the VEDA set of simulation tools deployed on nanoHUB.org cyber-infrastructure.