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In this study, we focus on the alteration of negative dielectrophoresis (n-DEP) caused by small amount of DNA labeling on the microbeads and propose a new design of microfluidic device for more sensitive DNA detection. In previous study, we proposed a new electrical technique for rapid detection of DNA amplified by polymerase chain reaction (PCR). The method is based on dramatic alteration of dielectrophoresis...
This document presents the mathematical model of a microfluidic device employing dielectrophoresis for purposes of 3D-focusing. The electrode configuration consists of multiple interdigitated transducer electrodes on either side of the bottom surface of the microchannel. The model consists of three equations of motion, one for each direction, equation of electric potential and electric field, and...
Dielectrophoretic force has been used to manipulate biological microparticles, such as red blood cells, white blood cells, cancer cells, etc… This technique has been used for trapping, sorting and separating biological particles suspended in a buffer medium. The strength of dielectrophoretic force depends strongly on the particle's electrical properties, the geometry of the microfluidic device, dielectric...
We report a flexible self-generated triboelectric microfluidic sensor based on liquid-solid triboelectrification and electrostatic induction mechanism. The flexible microfluidic sensor can be conformally attached on curved surfaces and work under two sensing modes - triboelectric single electrode mode and interdigital (IDT) electrode mode. The microfluidic sensor has linear force sensing range up...
We demonstrate fabrication of higher-order nanostructure for molecular sensing using dielectrophoresis-induced aggregation of Au-nanoparticles-decorated polystyrene beads (AuNPs/PS). We are also able to add the specific linker bridges which bind a target molecule. We achieved the in situ highly sensitive surface enhanced Raman Scattering using the higher-order nanostructure.
This work reports the experimental study of the dynamics of micro-droplets composed of two immiscible liquids and their separation into constituent phases in response to electrowetting-on-dielectric (EWOD) digital microfluidics (DMF) actuation. Separating phases of a compound droplet without leaving any residue of one phase to the other is a big challenge but much needed for successful operations...
A parallel dielectrophoretic single particle trap lab-on-a-chip system has been constructed and utilized to characterize the physical, electrical, and biological properties of single particle. We show proof-of-concept for the array of dielectrophoretic single particle trap that captures individual micro-/nano-particles in each trap.
This paper reports a novel bioMEMS device that integrates mechanical constriction for single cell trap in the channels, which are enclosed by thick (or 3D) C-PDMS (carbon-black-PDMS) electrodes and bottom planar transparent electrode for dielectrophoretic (DEP) cell manipulation. Leveraging hydrodynamics and dieletrophoresis, this simple biomedical microsystem enables more efficient loading of one...
This paper reports a low voltage DC digital microfluidics device working in air filler by inducing lateral electric field (ILEF), which enables manipulation of various positively charged and negatively charged polar solutions for biomedical applications in an oil-free digital microfluidic platform while using cheap DC electric power source. Sensitivity of threshold voltage (minimum required voltage...
In this work we describe the effect of Dielectrophoresis (DEP) on the deformation of red blood cells by measuring the change in aspect ratio. The force induced through DEP will act against the elastic force of the cell, lengthening and slimming the cell. The change in dimensions due to deformation under DEP is measured under a microscope, and when compared to DEP force applied, can provide useful...
In this paper, a simple method for cell dipping in a microfluidic device using dielectrophoresis is presented. A microfluidic system includes glass substrate and PDMS element is fabricated and tested. Cells dipping is performed and achieved using two sets of electrodes that slightly protrude into the microchannel through the sidewalls. The fabrication process and testing of the device are detailed.
In this paper, we designed and simulated a multilayer planar resonator with target frequency of 2.5 MHz which is created over a row/column-addressed 2D CMUT array. We have shown through finite element modeling and simulations that a particle can be trapped and manipulated both in lateral and axial directions inside the fluid channel by activating CMUT elements; And calculated acoustic radiation force...
Single cell manipulation technology has been widely applied in biological fields. Recently, a biochip platform with novel configuration of electrodes for cell 3-D rotation has been successfully developed. However, the rotation platform still has two major shortcomings of manual place of single cell and unstable rotation, which need to be addressed. To solve the two problems, in this paper we propose...
We have succeeded in injection of plasmid to adherent cells which are suspended in the plasma-bubbles laden circulation flow in a chamber. High-speed plasma-bubbles are generated by glass electrode and the air-liquid interface has a stiction force which draws the gene (plasmid) and stick to the air-liquid interface. The circulating flow increased the chances for cells to contact air-liquid interface...
A continuous label-free cell separation chip has been presented based on dielectrophoresis (DEP) utilizing the electrical properties of cells. The proposed microfluidic chip consists of three planar electrodes, where the positive DEP cells/particles were moved away from the central streamline while the negative DEP cell remained in the central streamline. DEP response were tested on polystyrene beads...
This study is focused on electroosmetic micromixer and the effects of driving force are investigated in the sense of different mixing channel width schemes. Two pairs of electrodes are mounted on the sidewalls of mixing channel to provide the required electric field. Various Numerical simulations are performed to assess the fluid flow in the presence of the electrokinetic driving force. Throughout...
We report on a distributed circuit model for multi-color light-actuated optoelectrowetting devices. The model takes into consideration the large variation of absorption coefficient (15×) of photoconductors in the visible spectrum and the nonuniform distribution of photogenerated carriers. With the help of this model, we designed opto-electrowetting devices with optimum thickness of photoconductors...
Separation of microparticles and living cells are studied with computational and experimental methods. The flow behaviors of particles are modeled and simulated using COMSOL Multiphysics 4.3a software. Lab-on-a-chip devices having a Ti interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to investigate the most effective design for separating particles based on...
In the present study a particle focusing technique has been developed for digital microfluidics (DMF) based on cumulative effects of negative dielectrophoretic (nDEP) and gravitational forces. The mechanism of the proposed technique has been studied for different particles, and different magnitudes and frequencies of the applied voltage. Particle focusing using the proposed technique was found to...
This paper introduces an advantageous self-mixing phenomenon created during the formation of aqueous two-phase systems in a digital microfluidic device, for the first time. The influence of such self-mixing on enhancement of on-chip extraction kinetics is quantified and reported, highlighting a significant mixing capability in the absence of forced mixing. Results suggest potential applications of...
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