Measurement of electric double layer thickness appearing on a interface between distilled water and glass by a fluid dynamic method

流体动力学法测量蒸馏水与玻璃界面上出现的双电层厚度

基本信息

批准号：
17560143
负责人：
KITOH Osami
金额：
$ 1.86万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

The main object of this research is to pursue a possibility of estimating the electric double layer thickness by fluid dynamic method. Strong shear flow prevails close to wall in a electroosmotic flow and the heat generation by flow resistance there gives rise to temperature distribution near the wall. By measuring the distribution, we can estimate the thickness of the electric-double layer. In this research program, (1) Revision of a experimental apparatus for precise measurements, (2) Development of high resolution precise thermometer and (3) Measurements of temperature distribution, were made. The results of each study are as follows.(1)An electroosmotic flow channel consists of two parallel donut-glass plates, whose gap h can be controlled within the accuracy of ±0.2μm in the range of 7μ m≦h≦80μm. Two glasses are set parallel to within 0.0016°. Using this channel, the characteristic relation between the flow rate and the applied voltage can be obtained that is consistent with the H … More elmholts-Smoluchowski theory. The electric current is a sum of bulk current and surface current as I=I_B+I_S. Here Is is a current through the electric double layer. Both currents cannot be measured separately so far. This new apparatus enable us to measure Is separately for the first time. The effect of the Joul-heating by Is on the temperature distribution can be estimated in addition to the fluid friction.(2)Because the designed platinum-wire micro thermometer, 1 μ in diameter and 0.5mm in length, has not enough stiffness when used in water, tungsten-wire having 3.1 μm diameter is used. The wire is insulated electrically by coating thin varnish (5μ m). The final performance of the meter are 0.02℃ temperature resolution with 15 μ m × 1mm spatial resolution. We are now developing a more precise thermometer by considering its stiffness and thinner varnish coating.(3)The measured temperature distribution at channel exit section shows about 0.5-degree rise from reference point at the wall. This temperature rise is the same order as that of estimated one in this research program, however, the uncertainty band of this measurement is rather high at this moment. To get more convinced results of the temperature distribution more technical improvements are required. Less

这项研究的主要目的是追求通过流体动态方法估算电气双层厚度的可能性。强剪切流在电流流动中占据靠近壁，并通过电阻产生热量，从而导致壁附近的温度分布。通过测量分布，我们可以估计电气双层的厚度。在该研究计划中，（1）对实验设备进行精确测量的修订，（2）开发高分辨率精度温度计和（3）测量温度分布。每项研究的结果如下。（1）电流流动通道由两个平行的甜甜圈玻璃板组成，其间隙H可以在7μm≦h≦80μm的范围内控制在±0.2μm的精度内。两个玻璃平行于0.0016°以内。使用此通道，可以获得与H…更多的Elmholts-Smoluchowski理论相一致的流速与应用电压之间的特征关系。电流是i = i_b+i_s的大量电流和表面电流的总和。这是通过电气双层电流。到目前为止，两种电流都不能单独测量。这种新的设备使我们能够第一次分别进行测量。除了流体摩擦外，还可以估算joul-heating iS对温度分布的影响。（2），因为设计的铂金 - 丝线微温度计，直径为1μm，长度为0.5 mm，在水中使用时刚度没有足够的刚度，tungsten-wire使用具有3.1μm直图的水。电线通过涂层薄清漆（5μm）进行电隔离。仪表的最终性能为0.02℃温度分辨率，空间分辨率为15μm×1 mm。现在，我们正在通过考虑其刚度和更薄的清漆涂层来开发更精确的温度计。（3）通道出口部分的测量温度分布显示出壁上参考点的0.5度上升。该温度升高与该研究计划中的估计量相同，但是，目前，该测量的不确定性频段相当高。为了获得更令人信服的温度分布结果，需要进行更多的技术改进。较少的