Spontaneous self-organization enables dielectrophoresis of small nanoparticles and formation of photoconductive microbridges.
Spontaneous self-organization enables dielectrophoresis of small nanoparticles and formation of photoconductive microbridges.
复制标题
自发自组织能够实现小纳米粒子的介电泳和光电导微桥的形成。
DOI：
10.1021/ja200422s
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发表时间：
2011
影响因子：
15
通讯作者：
Kotov,NicholasA
中科院分区：
文献类型：
--
作者：
Jung,Seung-Ho;Chen,Chen;Cha,Sang-Ho;Yeom,Bongjun;Bahng,JoongHwan;Srivastava,Sudhanshu;Zhu,Jian;Yang,Ming;Liu,Shaoqin;Kotov,NicholasA
对介电电泳（DEP）机理的深入理解及其对小尺寸量子化纳米颗粒（NPs）效率的大幅提高为微尺度和纳米尺度技术的融合打开了大门。然而，它受到体积低于几百立方纳米的颗粒中DEP力严重降低的阻碍。本文报道了在4-10 V的交流电压下，直径为4.2 nm的尺寸量子化CdTe纳米粒子（NPs）的DEP组装。对这些NPs的标称DEP力的计算表明，即使在最大的交流电压下，它也比布朗运动破坏组装体的力小几个数量级。尽管如此，即使对于6 V的AC电压和高度稀释的NP分散体，也观察到在由2 μm的间隙分开的电极之间非常有效地形成NP桥。这个难题的解决方案是在碲化镉纳米颗粒的内在自组装能力中发现的。由DEP组装的物种比单个NP大得多。DEP组装应视为长度为140 nm的NP链的过程。自组装链增加了发生粒子极化的标称体积，同时保留了材料的尺寸量子化性质。发现所产生的NP桥是光活性的，在照射时产生光电流。量子限制纳米粒子的DEP桥可用于新型MEMS组件、传感器以及光学和光电器件的快速并行制造。有目的地设计纳米颗粒的自组装特性使得进一步促进DEP和增加所产生的纳米尺度和微米尺度结构的复杂性成为可能。
Detailed understanding of the mechanism of dielectrophoresis (DEP) and the drastic improvement of its efficiency for small size-quantized nanoparticles (NPs) open the door for the convergence of microscale and nanoscale technologies. It is hindered, however, by the severe reduction of DEP force in particles with volumes below a few hundred cubic nanometers. We report here DEP assembly of size-quantized CdTe nanoparticles (NPs) with a diameter of 4.2 nm under AC voltage of 4–10 V. Calculations of the nominal DEP force for these NPs indicate that it isseveral orders of magnitude smallerthan the force of the Brownian motion destroying the assemblies even for the maximum applied AC voltage. Despite this, very efficient formation of NP bridges between electrodes separated by a gap of 2 μm was observed even for AC voltages of 6 V and highly diluted NP dispersions. The resolution of this conundrum was found in the intrinsic ability of CdTe NPs to self-assemble. The species being assembled by DEP are substantially bigger than the individual NPs. DEP assembly should be treated as a process taking place for NP chains with a length of ∼140 nm. The self-assembled chains increase the nominal volume where the polarization of the particles takes place, while retaining the size-quantized nature of the material. The produced NP bridges were found to be photoactive, producing photocurrent upon illumination. DEP bridges of quantum confined NPs can be used in fast parallel manufacturing of novel MEMS components, sensors, and optical and optoelectronic devices. Purposeful engineering of self-assembling properties of NPs makes possible further facilitation of the DEP and increase of complexity of the produced nano- and microscale structures.