非线性及粒子空间效应对交流电渗流泵的影响

Influence of Nolinear and Particle Steric Effect on AC Electroomosis Pumps

在交流电渗流(ACEO)泵的研究中,一般采用Debye-Huckel(D-H)线性近似法。但该方法只在电压很小时才成立,这和实际情况不符;此外,交流电渗流泵在大电压、高频率下的反向流现象也不能由D-H近似法给出正确的预测。当电压较大时,一般采用非线性的Poisson-Boltzmann(P-B)模型。但是,P-B模型也无法对交流电渗流泵在大电压、高频率下的反向流现象进行预测。在P-B模型中,溶液粒子被当作一个空间点,忽略了粒子间的相互作用以及粒子本身的空间体积效应。实际的粒子都有一定的空间体积,当电压较大、溶液浓度较高时,粒子的空间体积不应被忽略。由于粒子的空间体积,通过引入粒子空间效应对P-B模型进行修正后,给出了交流电渗流泵在较大电压下的数值模型,并对交流电渗流泵在较大电压下的高频率反向流现象进行了成功的预测。

In the study of AC electroomosis （ACEO） pump, the Debye-Huckel （D-H） linear approximation is used commonly. However, this method is valid only when the voltage is very small, and this situation is not identical with the practical situation. In addition, the reverse flow phenomenon of ACEO pumps at the large voltage and high frequency can not be predicted correctly by the D-H linear approximation. The nonlinear Poisson-Boltzmann （P-B） model is adopted at the large voltage generally, but the P-B model also can not predict the reverse flow phe nomenon of ACEO pumps at the large voltage and high frequency. In the P-B model, the solution particle is treated as a spatial point, the interaction among the particles and the steric effect of the particle itself are ignored. In fact, the particles have the finite size, and the finite size of particles should not be ignored at the large voltage and high solution concentration. According to the finite size of particles, the numerical model of ACEO pumps at the larger voltage was given by amending the P-B model with the particle steric effect, and the high frequency reverse flow phenomenon of ACEO pumps at the larger voltage was predicted successfully.