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

通过流体动态方法捕获电动双重厚度的主要对象。双重测量，（2）高分辨率的精确温度计和温度分布的测量值如下。 7μm的μm在使用此通道的0.0016°的范围内，可以平行于0.0016°。批量ASI = I_B+I_S的总和是驱动的，这是一个新的层。可以估计流体摩擦。。在墙壁上，温度升高是该研究计划的估计阶段