Dynamical modeling of manipulation process in Trolling-Mode AFM
Dynamical modeling of manipulation process in Trolling-Mode AFM
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DOI：
10.1016/j.ultramic.2018.11.017
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发表时间：
2019-02-01
期刊：
影响因子：
2.2
通讯作者：
Pishkenari, Hossein Nejat
中科院分区：
文献类型：
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作者：
Mohammadi, Seyedeh Zahra;Moghaddam, Majid;Pishkenari, Hossein Nejat
建立了用于生物样品操作的拖移式原子力显微镜的动力学集总模型。高精度和与生理条件的兼容性使AFM成为研究液体介质中生物材料的独特工具。然而，AFM微悬臂遭受严重的灵敏度下降和噪声加剧，而在液体中操作;悬臂和周围的液体之间的大的流体动力学拖曳力的尖端样品的相互作用力，这是重要的控制过程。因此，合适的纳米针应该足够长以保持悬臂远离液体介质，并且足够短以能够传递所需的力来推动纳米颗粒。尽管如此，长纳米针可能在推力下偏转;因此，其弯曲偏转应在控制方程中考虑。此外，进行纳米针和悬臂梁的解析和有限元应力分析，以确保它们所选择的材料和几何形状。JKR理论被用来模拟针/表面和颗粒之间的接触力学。阻力和弯月面力用于模拟液体介质。使用ODE 45求解控制方程，并模拟系统行为。得到了滑动的临界条件，包括临界时间和临界力，并给出了推力、针尖挠度和压痕深度的变化情况。此外，速度变化的影响进行了观察。然后，测试纳米针的不同高度，并为我们的目的选择合适的高度（以保持针远离液体并适当地传递力）。对各种生物颗粒重复模拟，并研究它们的行为。最后，通过与前人工作的比较，验证了本文模拟的有效性。这一比较表明，模拟对于预期目的是可靠的。
Dynamical lumped modeling of Trolling-mode AFM in manipulation of bio-samples is presented. The combination of high accuracy and compatibility with physiological conditions makes AFM a unique tool for studying biological materials in liquid medium. However, AFM microcantilever suffers from severe sensitivity degradation and noise intensification while operating in liquid; the large hydrodynamic drag between the cantilever and the surrounding liquid overwhelms the tip-sample interaction forces that are important in controlling the process. Therefore, an appropriate nanoneedle should be long enough to keep the cantilever out of liquid medium and short enough to be able to transmit the required force to push nanoparticle. Nonetheless, a long nanoneedle may deflect under the pushing force; therefore, its bending deflection should be accounted for in governing equations. Moreover, analytical and finite element stress analysis of nanoneedle and cantilever is performed to assure about their selected material and geometry. JKR theory is utilized to model contact mechanics between the needle/surface and the particle. Drag and meniscus forces are used to model the liquid media. Governing equations are solved using ODE45 and the system behavior is simulated. Critical conditions of sliding including critical time and force are obtained and changes of pushing force, needle deflection and indentation depths are illustrated. Also, effects of velocity variations are observed. Then, different heights for nanoneedle are tested and an appropriate one is selected for our purpose (to keep the needle out of liquid and transmit the force appropriately). The simulation is repeated for various biological particles and their behaviors are studied. At the end, the present simulation is validated through comparing the results with a previous work. This comparison shows that the simulation is reliable for the intended purpose.