Formation of Au Colloidal Crystals for Optical Sensing by DEP-Based Nano-Assembly

Leung, Gong Wai; Lau, Fong Ting; Leung, Siu Ling; Li, W.J.

doi:10.1109/nems.2007.352169

Cited by 8 publications

(6 citation statements)

References 21 publications

(13 reference statements)

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“…Khondaker and Yao [3] employed electrodes with a gap size of sub-10 nm, which are produced by breaking nanowires assembled from gold nanoparticles, to trap a thiol-coated 2-3 nm Au nanoparticle for the measurement of electrical transport, which shows a clear Coulomb staircase at 4.2 K. In addition, with 200 micrometer spaced electrodes, Yuan [10] exhibited the chaining and dendrite formation of gold particles with diameter of 2.5 nm using AC electric field, which ascribed to the combinational operation of DEP and convection. However, in our previous study with several micron electrode gap [9], such desired nanowires formed by 2 nm gold particles had not been achieved using DEP as predicted, which was imputed to the limitations of the Brownian motion and the viscous drag force of fluid motion.…”

Section: Introductionmentioning

confidence: 89%

“…As for a given electrode system, the voltage applied on the spaced electrodes is the critical control parameter to produce high intensity electric field for DEP. Consider the 2 nm gold particle solution with the aforementioned parameters, the velocities produced by these four effects, i.e., DEP, electro-thermal flow, AC electro-osmotic flow, and Brownian motion, can be estimated against the applied voltage V using equations (4), (7), (9), and (13). The results are shown in Fig.…”

Section: E Particle Assemblymentioning

confidence: 99%

“…ETALLIC nanoparticle assemblies into functional structures using DEP are of tremendous significance and has attracted considerable attention [1][2][3][4][5][6][7][8][9]. For molecular electronics, DEP was employed to trap nanoparticles to bridge nanogap electrodes for the application of electronic transport studies [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

“…For the self-repairing of broken circuits [4] and electrical connections [5] in liquid or biological environments, gold nanoparticles were assembled into microwires between micrometer gap electrodes using DEP technique. Nanowires with resolution down to several nanometers, which formed with gold nanoparticles of diameter range from 2 to 250 nm, have been demonstrated by several groups [2,[6][7][8][9]. However, only a few reports have demonstrated the effective manipulation of 2 nm gold particles using DEP.…”

Section: Introductionmentioning

confidence: 99%

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Dielectrophoretic assembly of 2 nm gold particles for nano-sensing applications

Leung

et al. 2010

2010 IEEE 5th International Conference on Nano/Micro Engineered and Molecular Systems

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This paper describes the assembly of 2 nm gold nanoparticles between micro-fabricated planar electrodes by using dielectrophoresis (DEP). The optimal conditions for effectively dieletrophoretic manipulation have been established through theoretical analysis and experimental validation. In the theoretical analysis, the effect of Brownian motion was taken into consideration, as well as the electrothermal flow and the AC electroosmosis flow. For effective manipulation of nanoparticles using DEP, proper high electric field strength is desired to give rise to dominate DEP effect, since the higher electric field strength increases the Joule heating and the lower strength reduces the DEP force. The current results indicate that the input voltage of 16Vp-p, 150 kHz leads to effective assembly of 2 nm gold nanoparticles. Our study proved that the DEP is capable of consistently assembling gold nanoparticles down to 2 nm in diameter with micro-fabricated electrodes, which was thought to be extremely difficult in the past.

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Section: Introductionmentioning

confidence: 89%

Section: E Particle Assemblymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dielectrophoretic assembly of 2 nm gold particles for nano-sensing applications

Leung

et al. 2010

2010 IEEE 5th International Conference on Nano/Micro Engineered and Molecular Systems

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“…Gold Nanoparticles (NPs) or colloidal have been extensively studied because of their potential applications in nano-medicine [1][2], nano-photonics [3] and nano-devices [4]. In the past few decades, varieties of nanowire fabrication techniques were developed.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of gold nano-particle based sensors using microspotting and DEP technologies

Leung

Lau

et al. 2008

2008 SICE Annual Conference

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Abstract:We have shown that Au nanoparticles (Au NPs) pearl chain could be formed consistently between microelectrodes by combining microspotting and DEP technologies. Experimental results on varying the Au particle size and dielectrophoretic (DEP) parameters, including voltage and frequency, are reported in this paper to explore the critical parameters in controlling the Pearl Chain Formation (PCF) process between microelectrodes. PCF was observed from 10kHz to 5MHz for 100nm Au NPs, and 100kHz to 10MHz for 10nm Au NPs. Variations in formation rate were detected when the applied voltage and particle size varied. With higher voltage, pearl chain began to form at higher rate and the formation time decreased. The optimum frequency of the Au NPs PCF shifted to higher frequency region when the particle size decreased. Theoretical analysis was carried out by applying the theories of DEP force and AC electrokinetics to explain the observations with the DEP frequency ranging from 10 Hz to 10MHz. Finally, Au nanoparticle chains formed between the microelectrodes were shown to vary in resistance when environmental temperature was changed, indicating that these Au particle sensors could potentially be used to sense temperature and other thermal-based physical phenomena.

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Contact-Free Templating of 3-D Colloidal Structures Using Spatially Nonuniform AC Electric Fields

Raveendran

Wood²,

Docoslis

2016

Langmuir

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The formation of ordered and regularly shaped structures of colloidal particles with the aid of spatially nonuniform electric fields is a modern research area of great interest. This work illustrates how alternating current (AC) electrokinetic effects (dielectrophoresis, electroosmosis) can serve as contact-free templates, inside which colloidal microspheres can assemble into a variety of shapes and sizes. We show how three-dimensional colloidal structures of square, circular, and diamond shape of many tens of micrometers in size can be reproducibly formed with a single set of quadrupolar microelectrodes. Numerical simulations performed help to explain the role of AC electroosmosis and AC dielectrophoresis on the shaping of these structures as a function of applied voltage and frequency. We also demonstrate how the templating repertoire is further enhanced with the simultaneous application of a second, individually controlled AC electric field, which enables a variety of asymmetric colloidal structures to be produced using the same set of quadrupolar microelectrodes. As the preservation of shape and size of such electric-field templated structures after medium evaporation still remains a big challenge, here we also report on a novel method that permits the stabilization and isolation of these particle assemblies through medium gelation and subsequent hydrogel removal with a UV/ozone treatment.

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Formation of Au Colloidal Crystals for Optical Sensing by DEP-Based Nano-Assembly

Cited by 8 publications

References 21 publications

Dielectrophoretic assembly of 2 nm gold particles for nano-sensing applications

Dielectrophoretic assembly of 2 nm gold particles for nano-sensing applications

Fabrication of gold nano-particle based sensors using microspotting and DEP technologies

Contact-Free Templating of 3-D Colloidal Structures Using Spatially Nonuniform AC Electric Fields

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