交流电热流场对微纳粒子介电泳行为的影响

Influence of AC Electrothermal Flow on the Dielctrophoretic Behaviors of Micro-nano Particles

以叉指电极阵列为例,分别建立对称物理场、非对称物理场和行波物理场的有限元模型,求解三种情况物理场下微通道中的电场、流场、温度场和介电泳力的分布,分析交流电热流场的对流与传质过程对流场中微纳粒子介电泳的影响规律和干预方式。结果表明,对称物理场和非对称物理场内部均产生漩涡式扰动,增强了流场的对流与传质,可将处于介电泳有效作用范围之外的微纳粒子输送至电极附近区域,扩展了介电泳的实际有效作用区域。行波叉指电极阵列构建的流场则无明显漩涡,但行波物理场中介电泳力的衰减较慢,电极厚度60倍高度处衰减为10%,显著提高了对微纳粒子的操控和输送能力。

Taking the case of interdigital electrode array,finite element models of symmetric/asymmetric physical field and travelling wave field are established respectively to solve the distribution of electric field,flow field,temperature and dielectrophoretic forces.The influence of AC electrothermal flow and the convective mass transfer process on the dielctrophoretic behaviors of micro-nano particles are presented herein.It is shown that the convection and mass transfer are enhanced due to the vortex generated by symmetric/asymmetric interdigital electrode array.As a result,the particles far away from the electrodes are transported towards the strong dielectrophoretic regions,enlarging the effective regions of dielectrophoresis.There is no obvious vortex and convections in the travelling wave flow field,but the dissipation of dielectrophoretic force is much slower than symmetric/asymmetric array,making the particles being trapped efficiently.The particles suspended at certain height（60 times of electrode height） can be affected by dielectrophoretic forces,improving the manipulating and transporting abilities for micro-nano particles.