Influence of Induced-Charge Electrokinetic Phenomena on the Dielectrophoretic Assembly of Gold Nanoparticles in a Conductive-Island-Based Microelectrode System
Influence of Induced-Charge Electrokinetic Phenomena on the Dielectrophoretic Assembly of Gold Nanoparticles in a Conductive-Island-Based Microelectrode System
复制标题
感应电荷动电现象对导电岛微电极系统中金纳米颗粒介电泳组装的影响
DOI：
10.1021/la402060g
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发表时间：
2013-10-01
期刊：
影响因子：
3.9
通讯作者：
Niu, Jiqiang
中科院分区：
文献类型：
--
作者：
Ding, Haitao;Liu, Weiyu;Niu, Jiqiang
液体悬浮液中的金属纳米粒子可以通过介电泳法(DEP)组装成纳米粒子链，这些纳米粒子链可以用作电气功能微线，将隔离的和导电的元件连接到电极对，如用于湿电子、生物电子和生化传感器。这些组装在电极对之间的纳米粒子链的频率依赖的形态甚至归因于交流电渗透(ACEs)流速随驱动频率的降低而减小。例如，只有在高频下才能通过DEP组装生成高度定向的纳米颗粒纳米线，这导致在电极表面上方产生可以忽略不计的小ACeO，对应于较少的纳米颗粒传输到组装区域。在这项研究中，注意力集中在导电岛基微电极系统中纳米粒子链的形成。值得注意的是，岛状实体的侵入会在导电物体周围产生进一步的双层极化和诱导电荷电渗流，这对DEP组装产生了重大影响。在我们的实验中，纳米粒子链的末端总是以50 kHz的频率延伸到金属表面，而它们的中心部分在150 kHz时变得细长。同时，沿局部电场线方向排列的线状粒子团簇在岛状边缘的分布比从电极边缘生长出来的更密集。因此，引入了一系列基于感应电荷电动力学理论的数值模型来解释这些规律性的实验结果，包括金属/电解液界面的双层充电效应、ACeO、iCeO和电热流动。当相邻粒子相互靠近时，相互DEP也被视为影响DEP行为的重要因素。理论研究结果与实验观测结果吻合较好。
Metal nanoparticles in a liquid suspension can be assembled dielectrophoretically (DEP) into nanoparticle chains, which can serve as electrical functional microwires connecting isolated and conductive elements to an electrode pair, as used in wet electronics, bioelectronics, and biochemical sensors. The frequency-dependent morphology of these nanoparticle chains assembled between an electrode pair has even been attributed to the decreasing magnitude of alternating current electroosmosis (ACEO) flow velocity with driving frequency. For instance, highly oriented nanoparticle nanowires can be generated by DEP assembly only at a high frequency, which induces a negligible small ACEO above the electrode surface, corresponding to fewer nanoparticles transported to the assembly region. In this study, attention is focused on the formation of nanoparticle chains in a conductive-island-based microelectrode system. It is worth noting that the intrusion of an island entity can bring about further double-layer polarization and induced charge electroosmosis flow (ICEO) around this conductive object, which exerts a significant influence on DEP assembly. In our experiments, the ends of nanoparticle chains are always extended onto the metal surfaces at 50 kHz, and their central parts become slender at 150 kHz. Meanwhile, wire-shaped particle clusters aligned along the direction of local field lines are more densely distributed at the island rims than that growing from the electrode edges. Consequently, a series of numerical modeling based on the theory of induced charge electrokinetic phenomena are introduced to account for these regular experimental results, including the double-layer charging effect at the metal/electrolyte interface, ACEO, ICEO, and electrothermal flow. Mutual DEP is also treated as an important factor affecting DEP behavior when neighboring particles are approaching one another. The results from the theoretical study are in good agreement with the experimental observations.