Electrofluidic Gating of a Chemically Reactive Surface
Electrofluidic Gating of a Chemically Reactive Surface
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DOI：
10.1021/la9044682
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发表时间：
2010-06-01
期刊：
影响因子：
3.9
通讯作者：
Stein, Derek
中科院分区：
文献类型：
--
作者：
Jiang, Zhijun;Stein, Derek
我们考虑了在化学反应表面上垂直于双电层施加的电场的影响。我们的目标是阐明表面化学如何影响场效应控制微纳流体系统的潜力，我们称之为电流控。首先对金属氧化物电解质（莫伊）电容器的充电进行了解析建模。我们应用Poisson-Boltzmann描述的双电层，并施加在固液界面的可电离的表面基团和溶液之间的化学平衡。化学反应的表面被预测为缓冲区，调节的电荷在双层质子化或去质子化响应所施加的电场。我们提出的双电层的电荷密度和电化学电位的依赖于所施加的电场，密度，和电离的表面基团的解离常数和离子强度和电解质的pH值。我们模拟了SiO2和Al 2 O3的响应。两种广泛使用的氧化物绝缘体具有不同的表面化学性质。我们还考虑的限制，施加的双电层的非线性行为和氧化物材料的介电强度，这是测量的二氧化硅和氧化铝薄膜中的莫伊配置的电流控。我们的研究结果阐明了化学反应表面对外加电场的响应，这对于理解真实的器件中的电流体效应至关重要。
We consider the influence of an electric field applied normal to the electric double layer at a chemically reactive surface. Our goal is to elucidate how surface chemistry affects the potential for field-effect control over micro- and nanofluidic systems, which we call electrofluidic gating. The charging of a metal-oxide-electrolyte (MOE) capacitor is first modeled analytically. We apply the Poisson-Boltzmann description of the double layer and impose chemical equilibrium between the ionizable surface groups and the solution at the solid-liquid interface. The chemically reactive surface is predicted to behave as a buffer, regulating the charge in the double layer by either protonating or deprotonating in response to the applied field. We present the dependence of the charge density and the electrochemical potential of the double layer on the applied field, the density, and the dissociation constants of ionizable surface groups and the ionic strength and the pH of the electrolyte. We simulate the responses of SiO2 and Al2O3. two widely used oxide insulators with different surface chemistries. We also consider the limits to electrofluidic gating imposed by the nonlinear behavior of the double layer and the dielectric strength of oxide materials, which were measured for SiO2 and Al2O3 films in MOE configurations. Our results clarify the response of chemically reactive surfaces to applied fields, which is crucial to understanding electrofluidic effects in real devices.