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Commonly, microelectrodes used in microfluidics are made from copper, Au or Pt. They are difficult to fabricate and the cost is relatively high. Thus, we designed and fabricated a novel microelectrode made from silicon for it is cheap and easy to fabricate. It has been proven that cells can be manipulated by dielectrophoresis force producing on interdigitated electrodes. In addition, the direction...
An amperometric biosensor based on Prussian blue (PB) modified indium tin oxide (ITO) electrode was developed. The roughness of PB film which affects the electrocatalytic properties of PB film was controlled by varying deposition voltage and time. Atomic force microscopy (AFM) was used to measure the roughness of PB films deposited under various conditions. We used capillary electrophoresis (CE) method...
Nowadays research on single CNT based nanoelectronic device arises much interest among researchers, but in the fabrication of CNT based nanoeletronic device, one of the key technical problems is to realize precise assembly and electrical contact between CNT and microelectrode. For solving the problem, first AC dieletrophoresis (DEP) method is used to coarsely position batch of CNTs near the microelectrode,...
Development and preliminary characterization on the performance of a micro-bubble generator using carbon nanotubes (CNTs) as heating elements are presented. Dielectrophoretic force was used to align CNTs between fabricated micro-electrodes. The contacts between the CNTs and electrodes were fixed by patterned SiO2 thin film. Localized high temperature due to Joule-heating generated by an AC current...
Dielectrophoretic concentrators were successfully developed on a EWOD-based chip. In such a chip, two major electrokinetic forces were exerted on objects on different scales. EWOD is used to pump droplets on a mm scale, while DEP manipulates bio-particles on a mum scale. Both cells and polystyrene beads were used to demonstrate the concentration abilities by pDEP and nDEP forces, respectively. Since...
We have demonstrated multi-walled carbon nanotube (MWCNTs) based sensors, which are capable of detecting alcohol vapor with ultra-low power. We fabricated the Si-substrate sensors using an AC electrophoretic technique so as to form bundled MWCNTs sensing elements between Au microelectrodes. The I-V measurement illustrates that we can activate the sensors at the Ohmic region of the sensors (at 10 muA),...
Fraction collection following DNA electrophoresis has many applications in biology analysis. These assays typically need to identify specific DNA fragments in the separated sample for further processing and require extraction of one or a group of fragments. Unfortunately, the conventional methods involve cumbersome procedure and are not amenable to integration, automation and extraction of microscale...
This paper presents the design and optimization of a dielectrophoresis-based cell separator by numerically analyzing the effects of geometrical dimensions on the separation performance and device safety in biological use. The separator uses negative DEP force to gather cells so that all cells have the same initial condition, and employs positive DEP to separate different cells. Simulation results...
In this paper steady electro-osmotic flow (EOF) in cross-straight channel is measured by micro particle image velocimetry (micro-PIV). Micro channels with two elementary configurations, a straight channel and a cross-straight channel, are fabricated by wet chemical etching process on glass. The uniform Zeta potential is obtained form the ratio of averaged velocities of EOF in the straight channel...
The new gel-immobilization method for preparing a single stranded DNA (ssDNA) template has been described for single nucleotide polymorphisms (SNPs) genotyping by bioluminometric assay based on allele-specfic extension reaction. In this method, PCR products amplified by a primer modified with acrylamide group at the 5'-terminal is copolymerized with acrylamide monomer to form gel. After the ssDNA...
A micro-pillar chip is proposed and developed to separate the amino acids, phenylalanine and tryptophan, through the aqueous two-phase system (ATPS). The surface properties of micro-pillars, specifically hydrophobicity and hydrophilicity for separation are also investigated. Because their isoelectric points (pI values) are similar, these amino acids are difficult to separate by general extraction...
A novel method for constructing an automated cell fractionation system was developed by integrating traveling-wave dielectrophoresis (twDEP) and laminar flow on a single biochip-based device. Novel electrodes designs on indium tin oxide (ITO) glass and pre-molded poly(dimethylsiloxane) (PDMS) microfluidic chamber, as well as an automated cell tracking method based on a computer-assisted image analysis...
Developing new methods to detect different electro-kinetic responses causing by biochemical differences was great scientific interest in the field of biophysics. An efficient method here was developed by using an electrokinetic system based on negative dielectrophoretic force (nDEP force) positioning and electrorotation (ROT). Electrokinetic responses of autotrophic and heterotrophic micro-algal cells...
In this study, we present the results of electroless deposition of silver (Ag) and electrophoretic deposition (EPD) of Al2O3 layers on glass for application in thin film transistor (TFT). Since silver with excellent resistivity is selected to be the material of electroless plating. We present a new method to deposit silver conductivity layer of TFT. Firstly, the desired pattern is defined by lithography...
This study presents the design, simulation, fabrication and preliminary results of a cell trap device for detecting the early stage of apoptosis, PS (phosph-atidylserine) exposure, under single-cell resolution. The structure of biochip is consisted of ITO top electrode, PDMS flow chamber, bottom electrode array and SU-8 3D microstructure array. In order to achieve single-cell resolution, we utilize...
EWOD (electrowetting-on-dielectric) and LDEP (liquid dielectrophoresis) are investigated to provide digital and analog microfluidic functions on an integrated chip respectively. By altering the frequency of the applied voltage and the surrounding medium of a EWOD device, we found that when using oil as surrounding medium and applying an AC signal 100 kHz, liquid column would be drawn and follow the...
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