Numerical Simulation of On-Chip Injection Process With Spatial Gradients of Electrical Conductivity

2003 ◽  
Author(s):  
Liqing Ren ◽  
Dongqing Li
Keyword(s):  
Transport Phenomena ◽  
Glass Plate ◽  
Concentration Field ◽  
Lab On A Chip ◽  
Theoretical Models ◽  
Spatial Gradient ◽  
Precise Control ◽  
Spatial Gradients ◽  
Injection Process ◽  
On Chip

The systematic design and precise control of the microfluidic dispenser (crossing microchannels etched into a plastic of glass plate) is key to the performance of many lab-on-a-chip devices. The fundamental understanding of the complicated electrokinetic phenomena in microfluidic dispensers therefore is necessary. In the literature, a few theoretical models studying the transport phenomena in similar crossing microchannels didn’t consider the spatial gradients of conductivity due to its complexity. A new theoretical model was developed in this paper to simulate the transport phenomena in a microfluidic dispenser with the consideration of a large range of spatial gradient of electric conductivity. This developed model was used to simulate the potential field, flow field, and concentration field of the injection processes where the conductivity of the sample-carrying buffer differs significantly from that of the driving buffer. The transport phenomena are found to be very sensitive to the conductivity difference between the sample-carrying buffer and the driving buffer. The developed model can be employed to find the optimal voltages for controlling the dispensed sample size and to provide guidance for designing such a microfluidic dispenser in lab-on-a-chip devices.

Numerical Studies of Injection Process Control With Spatial Gradients of Electrical Conductivity

2003 ◽  
Author(s):  
Liqing Ren ◽  
Dongqing Li
Keyword(s):  
Transport Phenomena ◽  
Glass Plate ◽  
Concentration Field ◽  
Lab On A Chip ◽  
Theoretical Models ◽  
Spatial Gradient ◽  
Precise Control ◽  
Spatial Gradients ◽  
Injection Process ◽  
Numerical Studies

The systematic design and precise control of the microfluidic dispenser (crossing microchannels etched into a plastic or glass plate) is key to the performance of many lab-on-a-chip devices. The fundamental understanding of the complicated electrokinetic phenomena in microfluidic dispensers therefore is necessary. In the literature, a few theoretical models studying the transport phenomena in similar crossing microchannels didn’t consider the spatial gradients of conductivity due to its complexity. A new theoretical model was developed in this paper to simulate the transport phenomena in a microfluidic dispenser with the consideration of a large range of spatial gradient of electric conductivity. This developed model was used to simulate the potential field, flow field, and concentration field of the injection processes where the conductivity of the sample-carrying buffer differs significantly from that of the driving buffer. The transport phenomena are found to be very sensitive to the conductivity difference between the sample-carrying buffer and the driving buffer. The developed model can be employed to find the optimal voltages for controlling the dispensed sample size and to provide guidance for designing such a microfluidic dispenser in lab-on-a-chip devices.

Justification of Non-Dimensional Schemes and Identification of Parameters on Modelling Electrokinetic Transport Phenomena in Microchannels

2010 ◽  
Author(s):  
Zhanjie Shao ◽  
Gerry Schneider ◽  
Carolyn Ren
Keyword(s):  
Initial Conditions ◽  
Transport Phenomena ◽  
Concentration Field ◽  
Electrokinetic Transport ◽  
Dimensional Model ◽  
Applied Potential ◽  
Governing Equations ◽  
Numerical Studies ◽  
Electrokinetic Flows ◽  
On Chip

The electrokinetic transport phenomena are to be numerically studied based on cross-linked microchannel networks, which have been commonly employed for on-chip capillary electrophoresis applications. Applied potential field, flow field and concentration field should be solved to predict the species transport process under electrokinetic flows. Together with the well-designed channel geometry, a detailed physical model was firstly formulated through a series of governing equations and corresponding boundary/initial conditions, which was briefly re-presented from our previous publications. The emphasis of current work was to justify the simplest non-dimensional scheme and identify the most beneficial parameters so that an effective and simplified non-dimensional model was developed for numerical studies.

scholarly journals 3D printed microfluidic lab-on-a-chip device for fiber-based dual beam optical manipulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haoran Wang ◽  
Anton Enders ◽  
John-Alexander Preuss ◽  
Janina Bahnemann ◽  
Alexander Heisterkamp ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Single Cells ◽  
Lab On A Chip ◽  
Cost Effective ◽  
Optical Manipulation ◽  
Hydrodynamic Focusing ◽  
Trapping Region ◽  
Dual Beam ◽  
3D Printed ◽  
On Chip

Abstract3D printing of microfluidic lab-on-a-chip devices enables rapid prototyping of robust and complex structures. In this work, we designed and fabricated a 3D printed lab-on-a-chip device for fiber-based dual beam optical manipulation. The final 3D printed chip offers three key features, such as (1) an optimized fiber channel design for precise alignment of optical fibers, (2) an optically clear window to visualize the trapping region, and (3) a sample channel which facilitates hydrodynamic focusing of samples. A square zig–zag structure incorporated in the sample channel increases the number of particles at the trapping site and focuses the cells and particles during experiments when operating the chip at low Reynolds number. To evaluate the performance of the device for optical manipulation, we implemented on-chip, fiber-based optical trapping of different-sized microscopic particles and performed trap stiffness measurements. In addition, optical stretching of MCF-7 cells was successfully accomplished for the purpose of studying the effects of a cytochalasin metabolite, pyrichalasin H, on cell elasticity. We observed distinct changes in the deformability of single cells treated with pyrichalasin H compared to untreated cells. These results demonstrate that 3D printed microfluidic lab-on-a-chip devices offer a cost-effective and customizable platform for applications in optical manipulation.

All-nanoparticle layer-by-layer coatings for Mid-IR on-chip gas sensing

2020 ◽  
Vol 56 (91) ◽  
pp. 14283-14286
Author(s):  
Diana Al Husseini ◽  
Junchao Zhou ◽  
Daniel Willhelm ◽  
Trevor Hastings ◽  
Gregory S. Day ◽  
...  
Keyword(s):  
Optical Waveguides ◽  
Gas Sensing ◽  
Layer By Layer ◽  
Precise Control ◽  
Nanoparticle Layer ◽  
Withdrawal Speed ◽  
Layer Deposition ◽  
Nanoparticle Coatings ◽  
On Chip

Functionalization of optical waveguides with submicron all-nanoparticle coatings significantly enhanced the detection of acetone. Such coatings were enabled via precise control of the substrate withdrawal speed using the layer-by-layer deposition.

scholarly journals Epidermal Growth Factor Receptor Distribution during Chemotactic Responses

2000 ◽  
Vol 11 (11) ◽  
pp. 3873-3883 ◽  
Author(s):  
Maryse Bailly ◽  
Jeffrey Wyckoff ◽  
Boumediene Bouzahzah ◽  
Ross Hammerman ◽  
Vonetta Sylvestre ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Fluorescent Protein ◽  
Growth Factor Receptor ◽  
Spatial Gradient ◽  
Spatial Gradients ◽  
Epidermal Growth ◽  
Green Fluorescent

To determine the distribution of the epidermal growth factor (EGF) receptor (EGFR) on the surface of cells responding to EGF as a chemoattractant, an EGFR-green fluorescent protein chimera was expressed in the MTLn3 mammary carcinoma cell line. The chimera was functional and easily visualized on the cell surface. In contrast to other studies indicating that the EGFR might be localized to certain regions of the plasma membrane, we found that the chimera is homogeneously distributed on the plasma membrane and becomes most concentrated in vesicles after endocytosis. In spatial gradients of EGF, endocytosed receptor accumulates on the upgradient side of the cell. Visualization of the binding of fluorescent EGF to cells reveals that the affinity properties of the receptor, together with its expression level on cells, can provide an initial amplification step in spatial gradient sensing.

On-Chip Platinum Micro-Heater with Platinum Temperature Sensor for a Fully Integrated Disposable PCR Module

2010 ◽  
Vol 93-94 ◽  
pp. 129-132 ◽  
Author(s):  
W. Sripumkhai ◽  
A. Lekwichai ◽  
Win Bunjongpru ◽  
S. Porntheeraphat ◽  
B. Tunhoo ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Temperature Sensor ◽  
Lab On A Chip ◽  
Conventional Pcr ◽  
Fully Integrated ◽  
On Chip

The on-chip platinum micro-heater prototypes for thermal cycling equipped with platinum temperature sensor are fabricated. The device has been designed, fabricated and characterized to explore the feasibility of the micro-heater for a fully integrated disposable lab-on-a-chip with the PCR module. The on-chip micro-heater demonstrates that the temperature transitions are shorter by comparison with the conventional PCR temperature routines.

scholarly journals Laser ultrasonic imaging of wavefield spatial gradients for damage detection

2020 ◽  
pp. 147592172095133
Author(s):  
Zihan Wu ◽  
See Yenn Chong ◽  
Michael D Todd
Keyword(s):  
Laser Scanning ◽  
Ultrasonic Imaging ◽  
Image Processing Technique ◽  
Spatial Gradient ◽  
Spatial Covariance ◽  
Laser Ultrasonic ◽  
Spatial Gradients ◽  
Orientation Map ◽  
Scanning Area ◽  
Damage Visualization

This article describes a new damage visualization method to investigate and analyze propagating guided Lamb waves using analyses of wavefield spatial gradients. A laser ultrasonic interrogation system was used to create full-field ultrasonic data measurements for ultrasonic wavefield imaging. The laser scanning process was performed based on both a raster scan and a circle scan. From the high-resolution wavefield data, a spatial gradient–based image processing technique was developed using gradient vectors to extract features sensitive to defects. Local impedance changes at the damaged area would result in a local distortion of the waveform which was captured and quantified by the variation of the gradient vectors in the scanning area as time evolves. Such variation was accumulated over time with a statistical threshold filter to generate a gradient-orientation map for damage visualization. The proposed algorithm was capable of producing distinctive damage patterns when tested experimentally on a 3-mm aluminum plate with multiple simultaneous simulated defects. Compared to conventional techniques like local wavenumber estimation, the generation of the accumulated orientation map involves no filtering process in the frequency or wavenumber domain, at the expense of more accurate shaping of the defect. A spatial covariance analysis was adopted to locate damage from the results as well as to evaluate the correlation between different kinds of defects. Combining the proposed approach with conventional laser ultrasonic imaging techniques enables a fast and robust damage identification and characterization process which requires lower computational burden and practical operation.

Differential Gene Expression of Endothelial Cells Under High Wall Shear Stress and Spatial Gradients

2010 ◽  
Author(s):  
Jennifer Dolan ◽  
Song Liu ◽  
Hui Meng ◽  
John Kolega
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Vessel Wall ◽  
Cerebral Aneurysms ◽  
In Vivo Studies ◽  
Spatial Gradient ◽  
Flow Acceleration ◽  
Spatial Gradients ◽  
Wall Shear

In both human and animal models, cerebral aneurysms tend to develop at the apices of bifurcations in the cerebral vasculature. Due to the focal nature of aneurysm development it has long been speculated that hemodynamics are an important factor in aneurysm susceptibility. The local hemodynamics of bifurcations are complex, being characterized by flow impingement causing a high frictional force on the vessel wall known as wall shear stress (WSS) and significant flow acceleration or deceleration, manifested as the positive or negative spatial gradient of WSS (WSSG). In vivo studies have recently identified that aneurysm initiation occurs at areas of the vessel wall that experience a combination of both high WSS and positive WSSG [1,2]

scholarly journals Miniaturization of fluorescence sensing in optofluidic devices

2020 ◽  
Vol 24 (9) ◽  
Author(s):  
Daniel Măriuţa ◽  
Stéphane Colin ◽  
Christine Barrot-Lattes ◽  
Stéphane Le Calvé ◽  
Jan G. Korvink ◽  
...  
Keyword(s):  
Lab On A Chip ◽  
Time Data ◽  
Fluorescence Sensing ◽  
Successful Development ◽  
Total Analysis System ◽  
Total Analysis ◽  
Integration Strategies ◽  
Analysis System ◽  
On Chip ◽  
Industrial Sensing

Abstract Successful development of a micro-total-analysis system (µTAS, lab-on-a-chip) is strictly related to the degree of miniaturization, integration, autonomy, sensitivity, selectivity, and repeatability of its detector. Fluorescence sensing is an optical detection method used for a large variety of biological and chemical assays, and its full integration within lab-on-a-chip devices remains a challenge. Important achievements were reported during the last few years, including improvements of previously reported methodologies, as well as new integration strategies. However, a universal paradigm remains elusive. This review considers achievements in the field of fluorescence sensing miniaturization, starting from off-chip approaches, representing miniaturized versions of their lab counter-parts, continuing gradually with strategies that aim to fully integrate fluorescence detection on-chip, and reporting the results around integration strategies based on optical-fiber-based designs, optical layer integrated designs, CMOS-based fluorescence sensing, and organic electronics. Further successful development in this field would enable the implementation of sensing networks in specific environments that, when coupled to Internet-of-Things (IoT) and artificial intelligence (AI), could provide real-time data collection and, therefore, revolutionize fields like health, environmental, and industrial sensing.

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