Search results for "dielectrophoresis"

Molecular devices for nanoelectronics and plasmonics

2009

This thesis is focused on fabrication and characterization of molecular devices. In connection with molecular electronics the dielectrophoresis based method for trapping and attaching nanoscale double-stranded DNA between nanoelectrodes was developed. Moreover, the method was extended to self-assembled DNA nanostructures. The method allowed to obtain valuable information about electrical and dielectrophoretic properties of DNA. In addition, two general approaches to the utilization of DNA origami structures for the assembly of materials are described and experimentally demonstrated. In context of molecular plasmonics, a novel lithographic fabrication method for positioning dye molecules on …

Field-induced nanolithography for high-throughput pattern transfer.

2009

Carbon nanotubes as electrodes for dielectrophoresis of DNA

2006

Dielectrophoresis can potentially be used as an efficient trapping tool in the fabrication of molecular devices. For nanoscale objects, however, the Brownian motion poses a challenge. We show that the use of carbon nanotube electrodes makes it possible to apply relatively low trapping voltages and still achieve high enough field gradients for trapping nanoscale objects, e.g., single molecules. We compare the efficiency and other characteristics of dielectrophoresis between carbon nanotube electrodes and lithographically fabricated metallic electrodes, in the case of trapping nanoscale DNA molecules. The results are analyzed using finite element method simulations and reveal information abou…

Dielectrophoretic trapping of DNA origami.

2008

In this thesis three-dimensional tube-shaped DNA-origamis were dielectrophoretically trapped within lithographically fabricated nanoelectrodes. The origamis had been premade while the electrodes were fabricated specifically for these experiments with two different gapsizes, 150 nm and 400 nm. The aim of the work was to capture individual nanotubes in the gap between the electrodes by utilizing the dielectrophoretic forces present in the structure when a solution containing the origamis was put onto the electrodes and a voltage was applied. It was observed during the experiments that the success of the dielectrophoretic trapping depended strongly on the trapping conditions. This caused the t…

Dielectrophoretic trapping of multilayer DNA origami nanostructures and DNA origami-induced local destruction of silicon dioxide

2015

DNA origami is a widely used method for fabrication of custom-shaped nanostructures. However, to utilize such structures, one needs to controllably position them on nanoscale. Here we demonstrate how different types of 3D scaffolded multilayer origamis can be accurately anchored to lithographically fabricated nanoelectrodes on a silicon dioxide substrate by DEP. Straight brick-like origami structures, constructed both in square (SQL) and honeycomb lattices, as well as curved "C"-shaped and angular "L"-shaped origamis were trapped with nanoscale precision and single-structure accuracy. We show that the positioning and immobilization of all these structures can be realized with or without thi…

Sensing properties of assembled Bi2S3nanowire arrays

2015

Bismuth sulfide (Bi2S3) nanowires were grown in porous aluminium oxide template and a selective chemical etching was applied to transfer the nanowires to a solution. Well aligned nanowire arrays were assembled on pre-patterned silicon substrates employing dielectrophoresis. Electron beam lithography was used to connect aligned individual nanowires to the common macroelectrode. In order to evaluate the conductometric sensing performance of the Bi2S3 nanowires, current–voltage characteristics were measured at different relative humidity (RH) levels (5–80%) / argon medium. The response of the Bi2S3 nanowires depending of RH is found to be considerably different from those reported for other ty…

Trapping of 27 bp–8 kbp DNA and immobilization of thiol-modified DNA using dielectrophoresis

2006

Dielectrophoretic trapping of six different DNA fragments, sizes varying from the 27 to 8416 bp, has been studied using confocal microscopy. The effect of the DNA length and the size of the constriction between nanoscale fingertip electrodes on the trapping efficiency have been investigated. Using finite element method simulations in conjunction with the analysis of the experimental data, the polarizabilities of the different size DNA fragments have been calculated for different frequencies. Also the immobilization of trapped hexanethiol- and DTPA-modified 140 nm long DNA to the end of gold nanoelectrodes was experimentally quantified and the observations were supported by density functiona…

Seed layer technique for high quality epitaxial manganite films

2016

We introduce an innovative approach to the simultaneous control of growth mode and magnetotransport properties of manganite thin films, based on an easy-to-implement film/substrate interface engineering. The deposition of a manganite seed layer and the optimization of the substrate temperature allows a persistent bi-dimensional epitaxy and robust ferromagnetic properties at the same time. Structural measurements confirm that in such interface-engineered films, the optimal properties are related to improved epitaxy. A new growth scenario is envisaged, compatible with a shift from heteroepitaxy towards pseudo-homoepitaxy. Relevant growth parameters such as formation energy, roughening tempera…

Characterization of the conductance mechanisms of DNA origami by AC impedance spectroscopy.

2009

Theoretical and experimental study of the kinetics of particle chains near electrodes in dielectrophoretic devices

2014

Using a three dimensional coupled Monte Carlo-Poisson algorithm and experimental results we studied the role of the particle-particle dipole interaction on the kinetics of a system of human cells suspended in a static liquid medium under the action of an oscillating non-uniform electric field generated by polynomial electrodes. We found that the kinetics of the cells during negative/repulsive dielectrophoresis depends on the local distribution of particles. If the cells have generated long chains during positive/attractive dielectrophoresis, such chains can hinder subsequent detachment resulting in a reduction of the separation/manipulation efficiency of dielectrophoretic device. This effec…