Enhanced quality factors and force sensitivity by attaching magnetic beads to cantilevers for atomic force microscopy in liquid
Enhanced quality factors and force sensitivity by attaching magnetic beads to cantilevers for atomic force microscopy in liquid
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DOI：
10.1063/1.4768713
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发表时间：
2012-11
影响因子：
3.2
通讯作者：
S. Hoof;N. Gosvami;B. Hoogenboom
中科院分区：
文献类型：
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作者：
S. Hoof;N. Gosvami;B. Hoogenboom
由于悬臂共振的强粘性阻尼，液体中的动态模式原子力显微镜（AFM）仍然很复杂。在这里，我们表明，通过在纳克悬臂末端附着微克珠，可以在水溶液中实现高质量共振（Q>20）。由此产生的悬臂质量增加导致共振频率显着下降。然而，由于品质因数增强，力灵敏度（通过最小可检测力梯度表示）几乎不受影响。通过提高品质因数，附加的磁珠还降低了偏转检测器中噪声的相对重要性。因此，当检测器噪声很大时，它可以产生改进的信噪比。我们描述和分析了包括悬臂磁驱动的设置的这些效应，并且可以在与倒置光学显微镜兼容的任何 AFM 系统中轻松实现。
Dynamic-mode atomic force microscopy (AFM) in liquid remains complicated due to the strong viscous damping of the cantilever resonance. Here, we show that a high-quality resonance (Q>20) can be achieved in aqueous solution by attaching a microgram-bead at the end of the nanogram-cantilever. The resulting increase in cantilever mass causes the resonance frequency to drop significantly. However, the force sensitivity—as expressed via the minimum detectable force gradient—is hardly affected, because of the enhanced quality factor. Through the enhancement of the quality factor, the attached bead also reduces the relative importance of noise in the deflection detector. It can thus yield an improved signal-to-noise ratio when this detector noise is significant. We describe and analyze these effects for a set-up that includes magnetic actuation of the cantilevers and that can be easily implemented in any AFM system that is compatible with an inverted optical microscope.