Development of Micro Flow Systems utilizing Functional Fluids of non-Suspension Type

我们一直在尝试开发微流系统，利用分子排列或电场中液晶的电对流应用于微机器。针对微阻尼器或微润滑系统，研究了电场强度和交流电场频率对窄间隙电流变效应的影响。得到以下结果：(1)在直流电场中，分子排列的ER效应比电对流的ER效应更大。在交流电场中，分子排列引起ER效应，得到的ER效应与在直流电场中几乎相同。从工业应用的角度出发，认为交流电场作用下的流动对微阻尼器和微润滑系统的电流变效应的稳定性具有优势。(2)内流效应的瞬态响应与光学响应基本一致。(3)在缝隙很窄（<10 μ m）的情况下，内质网效应随着壁面效应而减弱。具有正介电各向异性的液晶在这方面是有用的。我们还研究了一种控制电对流的微流发生器（微泵）。电场在两个电极梳之间由上游向下游产生。我们无法充分控制电子对流，但在该装置中产生了微弱的流动。因此，可以说这些结果将应用于微泵和微致动器的研制。以上结果说明了液晶在微流系统中的高适用性。目前，我们正在开发另一种利用液晶电对流的流动系统。

We have been trying the development of micro flow systems utilizing the molecular alignment or the electroconvection of the liquid crystal in electric fields for an application to the micro machine. Relating to a micro damper or a micro lubrication system, we have investigated the influence of the electric field strength and the frequency of AC electric fields on the electrorheological (ER) effects in the narrow gaps. The following results are obtained : (1) In the DC electric field, a larger ER effect is obtained in the case of a molecular alignment than of the electroconvection. In the AC electric field, the ER effect is caused with the molecular alignment and nearly the same ER effect as in the DC electric field is obtained. In the view point of the industrial application, it is considered that the flow under the AC electric field has an advantage in the stability of the ER effect for the micro damper and micro lubrication system. (2) A transient response in the ER effect is nearly the same as the optical response. (3) In the case of very narrow gap (<10 mum), ER effect is decreased with the wall effect. (4) Liquid crystal with a positive dielectric anisotropy is useful in this purpose.We have also examined a micro flow generator (micro pump) by controlling the electroconvection. The electric field is yielded from up-stream to down-stream between two electrode combs faced each other. We couldn't control the electronconvection enough but a weak flow is generated in this apparatus. So, it may be said that these results will be applied to a micro pump and a micro actuator development.It is shown the high applicability of the liquid crystal to the micro flow systems from above results. Now we are developing the another type flow systems utilizing the electroconvection of liquid crystal.