Measurements of force working on micro particles under surface tension gradient in liquid by using Atomic Force Microscope

本课题的主要目的是研究在液体中颗粒存在工作表面张力梯度的情况下，颗粒在液体中从高表面张力到低表面张力的运动规律。为此，（1）用马赫曾德干涉仪观察颗粒运动和测量表面张力梯度，（2）用原子力显微镜（AFM）测量颗粒表面张力，（3）从理论上考虑液-气界面上的Marangoni效应。（4）细胞因子浓度梯度对中性粒细胞（白色血细胞）趋化性的影响，这与表面张力梯度下的颗粒过程非常相似。研究结果表明：（1）在温度梯度（表面张力梯度）作用下，石墨颗粒在水中的沉降速度小于在等温水中的沉降速度。颗粒粒径越大，沉降速度的方差越大。理论思考可以解释这些事实。（2）温度梯度对颗粒受力的影响很小，石墨颗粒受力大于聚苯乙烯（PS）颗粒。（3）滴加细胞因子液可观察到中性粒细胞的运动。当浓度下降到10 ng/ml时，从低浓度到高浓度的速度出现最大值。

The aim of this research topic is to investigate the particulate motions from higher surface tension to lower surface tension in the liquid In case of working surface tension gradient on particulate in liquids. For this purpose, (1)the observation of particulate motions and measurement of surface tension gradient using Machzender interferometer, (2)measurement of feree worked on the particulate using atomic force microscopy(AFM), (3)theoretical consideration of Marangoni effect on the surface between liquid and gas are executed., (4)Effects of cytokine concentration gradient on chemotaxis of neutrophile (white blood cells)that is very similar phenomena to the particulate process under the surface tension gradient. The results of these topics are as follows :(1)Sinking velocity of graphite particulate under temperature gradient (surface tension gradient) in water is smaller than that in isothermal water. The larger the size of the particulate is, the larger variance of sinking velocity becomes. Theoretical consideration can explain these facts.(2)Effects of temperature gradient on worked force of the particulate is very small, and force on graphite particulate is larger than Polystyrene(PS) particulate.(3)The motion of neutrophile by dropping cytokine liquid can be observed. Velocity from the lower concentration to higher concentration has maximum point in case of 10 ng/ml concentration dropping.