School of Chemistry, F11, The University of Sydney, NSW 2006, Australia.
Langmuir. 2011 Jun 7;27(11):6701-11. doi: 10.1021/la2007809. Epub 2011 May 4.
We developed a stable spread-sheet algorithm for the calculation of the hydrodynamic forces measured by colloid probe atomic force microscopy to be used in investigations of interfacial slip. The algorithm quantifies the effect on the slip hydrodynamic force for factors commonly encountered in experimental measurements such as nanoparticle contamination, nonconstant drag force due to cantilever bending that varies with different cantilevers, flattening of the microsphere, and calibration at large separations. We found that all of these experimental factors significantly affect the fitted slip length, approximately in the order listed. Our modeling is applied to fit new experimental data reproducibly. Using this new algorithm, it is shown that the fitting of hydrodynamic theories to experimental data is reliable and the fitted slip length is accurate. A "blind test" protocol was developed that produces a reliable estimate of the fitting error in the determination of both the slip length and spring constant. By this blind test, we estimate that our modeling determines the fitted slip length with an average systematic error of 2 nm and the fitted spring constant with a 3% error. Our exact calculation of the drag force may explain previous reports that the fitted slip length depends upon the shape and spring constant of the cantilever used to perform the measurements.
我们开发了一种稳定的电子表格算法，用于计算胶体探针原子力显微镜测量的流体动力，以用于界面滑移的研究。该算法量化了在实验测量中常见的因素对滑移流体动力的影响，例如纳米颗粒污染、由于悬臂梁弯曲而导致的非恒定阻力，不同悬臂梁的阻力不同、微球的扁平化以及在较大分离时的校准。我们发现所有这些实验因素都显著影响拟合的滑移长度，大致按上述顺序排列。我们的建模应用于可重复拟合新的实验数据。使用这种新算法，表明将流体动力理论拟合到实验数据是可靠的，并且拟合的滑移长度是准确的。开发了一种“盲测试”协议，可可靠估计确定滑移长度和弹簧常数的拟合误差。通过这种盲测试，我们估计我们的建模确定拟合的滑移长度的平均系统误差为 2nm，拟合的弹簧常数的误差为 3%。我们对阻力的精确计算可以解释以前的报告，即拟合的滑移长度取决于用于进行测量的悬臂梁的形状和弹簧常数。
