Local viscosity probed by photonic force microscopy
Local viscosity probed by photonic force microscopy
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DOI：
10.1007/s003390051102
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发表时间：
1998-03-01
影响因子：
2.7
通讯作者：
Horber, JKH
中科院分区：
文献类型：
--
作者：
Pralle, A;Florin, EL;Horber, JKH
以纳米级空间分辨率和25微米S时间分辨率在不同距离记录了用作光子力显微镜探针的0.5微米和1微米聚苯乙烯微球的布朗运动。分析了布朗运动0.4s的时间窗，确定了扩散常数和局部粘性。使用0.5微米的球体可以测量小到1微米(3)的体积，在0.4 S范围内具有+/-15%的精度。在从3微米到200 nm的球面间隔内，连续测量了由于表面附近的部分限制而引起的扩散系数的减小。粘性阻力的增加与Brenner的分析结果一致[1]。
The Brownian motion of 0.5 mu m and 1 mu m polystyrene spheres used as probes for a photonic force microscope is recorded at various distances from a surface with nanometer spatial and 25 mu s temporal resolution. Analyzing time-windows of 0.4s of the Brownian motion, the diffusion constant and local viscosity are determined. Using 0.5 mu m spheres the viscosity can be measured in volumes as small as 1 mu m(3) with +/-15% precision within 0.4 s. The decrease of the diffusion coefficient due to the partial confinement near a surface is measured continuously over sphere-surface separations from 3 mu m down to 200 nm. The increase in viscous drag is found to agree with Brenner's analytical result [1].