Dielectrophoretic and electrothermal effects at alternating current heated disk microelectrodes.
Dielectrophoretic and electrothermal effects at alternating current heated disk microelectrodes.
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DOI：
10.1021/ac801094s
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发表时间：
2008-09
影响因子：
7.4
通讯作者：
A. Boika;A. Baranski
中科院分区：
文献类型：
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作者：
A. Boika;A. Baranski
当圆盘微电极以非常高频率（0.1- 2GHz）和高振幅（高达2.8V rms）的交变电位极化时，电极被加热，同时，在电极周围产生非常强的电场（对于半径为1微米的电极，>10（6）V/m）。该强电场引起正或负介电电泳效应。正介电电泳效应可用于在电极边缘处从纳米颗粒组装纳米线。另一方面，负介电电泳效应可能是负责“射流沸腾”观察到过热的微电极。此外，高温度梯度和高电势梯度的组合产生强烈的溶液对流，这非常强烈地增强了质量传递，并且是这种系统中强烈对流的原因。由于电极的高频交流极化不干扰分析信号的采集，因此可以在电化学检测中使用的微电极上直接产生微流和介电泳力。
When a disk microelectrode is polarized with an alternating potential of very high frequency (0.1-2 GHz) and a high amplitude (up to 2.8 V rms), the electrode is heated up, and at the same time, a very intense electric field is created around the electrode (>10(6) V/m for electrodes 1 microm in radius). This strong electric field gives rise to positive or negative dielectrophoretic effects. Positive dielectrophoretic effects can be used to assemble nanowires from nanoparticles at the electrode edge. On the other hand, a negative dielectrophoretic effect is probably responsible for "jet boiling" observed at overheated microelectrodes. In addition, a combination of a high temperature gradient and a high potential gradient generates an intense electrothermal flow of solution which very strongly enhances the mass transport and is responsible for intense convection in such systems. The electrothermal flow and dielectrophoretic forces can be generated directly on a microelectrode employed in electrochemical detection because the high frequency ac polarization of the electrode does not interfere with the acquisition of analytical signals.