scholarly journals Finger-Actuated Microfluidic Concentration Gradient Generator Compatible with a Microplate

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 174 ◽  
Author(s):  
Juhwan Park ◽  
Hyewon Roh ◽  
Je-Kyun Park
Keyword(s):  
Microfluidic Device ◽  
Concentration Gradient ◽  
Volume Of Fluid ◽  
Initial Reaction Rate ◽  
Initial Reaction ◽  
Concentration Gradients ◽  
Fluidic Channel ◽  
Push Button ◽  
Gradient Generator ◽  
Wide Range

The generation of concentration gradients is an essential part of a wide range of laboratory settings. However, the task usually requires tedious and repetitive steps and it is difficult to generate concentration gradients at once. Here, we present a microfluidic device that easily generates a concentration gradient by means of push-button actuated pumping units. The device is designed to generate six concentrations with a linear gradient between two different sample solutions. The microfluidic concentration gradient generator we report here does not require external pumps because changes in the pressure of the fluidic channel induced by finger actuation generate a constant volume of fluid, and the design of the generator is compatible with the commonly used 96-well microplate. Generation of a concentration gradient by the finger-actuated microfluidic device was consistent with that of the manual pipetting method. In addition, the amount of fluid dispensed from each outlet was constant when the button was pressed, and the volume of fluid increased linearly with respect to the number of pushing times. Coefficient of variation (CV) was between 0.796% and 13.539%, and the error was between 0.111% and 19.147%. The design of the microfluidic network, as well as the amount of fluid dispensed from each outlet at a single finger actuation, can be adjusted to the user’s demand. To prove the applicability of the concentration gradient generator, an enzyme assay was performed using alkaline phosphatase (ALP) and para-nitrophenyl phosphate (pNPP). We generated a linear concentration gradient of the pNPP substrate, and the enzyme kinetics of ALP was studied by examining the initial reaction rate between ALP and pNPP. Then, a Hanes–Woolf plot of the various concentration of ALP was drawn and the Vmax and Km value were calculated.

scholarly journals A Concentration Gradients Tunable Generator with Adjustable Position of the Acoustically Oscillating Bubbles

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 827
Author(s):  
Bendong Liu ◽  
Zhigao Ma ◽  
Jiahui Yang ◽  
Guohua Gao ◽  
Haibin Liu
Keyword(s):  
Concentration Gradient ◽  
Acoustic Waves ◽  
Gas Permeability ◽  
Liquid Interface ◽  
Biological Research ◽  
Concentration Gradients ◽  
New Device ◽  
Gradient Generator ◽  
Oscillating Bubbles ◽  
Pdms Chip

It is essential to control concentration gradients at specific locations for many biochemical experiments. This paper proposes a tunable concentration gradient generator actuated by acoustically oscillating bubbles trapped in the bubble channels using a controllable position based on the gas permeability of polydimethylsiloxane (PDMS). The gradient generator consists of a glass substrate, a PDMS chip, and a piezoelectric transducer. When the trapped bubbles are activated by acoustic waves, the solution near the gas–liquid interface is mixed. The volume of the bubbles and the position of the gas–liquid interface are regulated through the permeability of the PDMS wall. The tunable concentration gradient can be realized by changing the numbers and positions of the bubbles that enable the mixing of fluids in the main channel, and the amplitude of the applied voltage. This new device is easy to fabricate, responsive, and biocompatible, and therefore has great application prospects. In particular, it is suitable for biological research with high requirements for temporal controllability.

Biodetection using a ZnO nanorod-based microfluidic device with a concentration gradient generator

2020 ◽  
Vol 44 (14) ◽  
pp. 5186-5189
Author(s):  
Yan Xie ◽  
Yuchen Shi ◽  
Wenhui Xie ◽  
Mengjie Chang ◽  
Zhenjie Zhao ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Concentration Gradient ◽  
Cancer Biomarker ◽  
Zno Nanorod ◽  
Biomarker Detection ◽  
Gradient Generator

An effective microfluidic device with a concentration gradient generator for cancer biomarker detection is developed by integrating ZnO NR arrays into microchannels.

scholarly journals Concentration Gradient Constructions Using Inertial Microfluidics for Studying Tumor Cell–Drug Interactions

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 493
Author(s):  
Shaofei Shen ◽  
Fangjuan Zhang ◽  
Mengqi Gao ◽  
Yanbing Niu
Keyword(s):  
Tumor Cell ◽  
Drug Interactions ◽  
Cell Lines ◽  
Drug Concentration ◽  
Concentration Gradient ◽  
Breast Adenocarcinoma ◽  
Tumor Cell Lines ◽  
Concentration Gradients ◽  
Flow Rates ◽  
Wide Range

With the continuous development of cancer therapy, conventional animal models have exposed a series of shortcomings such as ethical issues, being time consuming and having an expensive cost. As an alternative method, microfluidic devices have shown advantages in drug screening, which can effectively shorten experimental time, reduce costs, improve efficiency, and achieve a large-scale, high-throughput and accurate analysis. However, most of these microfluidic technologies are established for narrow-range drug-concentration screening based on sensitive but limited flow rates. More simple, easy-to operate and wide-ranging concentration-gradient constructions for studying tumor cell–drug interactions in real-time have remained largely out of reach. Here, we proposed a simple and compact device that can quickly construct efficient and reliable drug-concentration gradients with a wide range of flow rates. The dynamic study of concentration-gradient formation based on successive spiral mixer regulations was investigated systematically and quantitatively. Accurate, stable, and controllable dual drug-concentration gradients were produced to evaluate simultaneously the efficacy of the anticancer drug against two tumor cell lines (human breast adenocarcinoma cells and human cervical carcinoma cells). Results showed that paclitaxel had dose-dependent effects on the two tumor cell lines under the same conditions, respectively. We expect this device to contribute to the development of microfluidic chips as a portable and economical product in terms of the potential of concentration gradient-related biochemical research.

Numerical and Experimental Study on a Microfluidic Concentration Gradient Generator for Arbitrary Approximate Linear and Quadratic Concentration Curve Output

2017 ◽  
Vol 16 (1) ◽  
Author(s):  
Xueye Chen ◽  
Zengliang Hu ◽  
Lei Zhang ◽  
Zhen Yao ◽  
Xiaodong Chen ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Concentration Gradient ◽  
Fluid Dynamic ◽  
Milling Machine ◽  
Microfluidic Chips ◽  
The Finite Element Method ◽  
Pmma Substrate ◽  
Concentration Gradients ◽  
Biochemical Engineering ◽  
Gradient Generator

AbstractThis work introduces a simple and versatile method for researching the concentration gradient generator (CGG) which can present the arbitrary approximate linear and quadratic concentration gradient curves output. The concentration gradients of arbitrary approximate linear curves with two inlets and arbitrary quadratic curves in the CGG with three inlets are obtained with the corresponding flow velocities. The CGG was simulated basing on the finite element method (FEM). The fluid-dynamic and mass-transport about the CGG was studied. Moreover, the feasibility of simulation was clearly verified by an experiment which two microfluidic chips of CGG on the PMMA substrate were processed using CNC engraving and milling machine. The paper successfully demonstrates the controllability of concentration gradient profiles in CGG with two inlets and three inlets. The study on the CGG can help the trends study of cell and molecule in different samples in the biochemical engineering.

Electrokinetic Concentration Gradient Generation Using a Converging-Diverging Microchannel

2005 ◽  
Author(s):  
Jacky S. H. Lee ◽  
Yandong Hu ◽  
Dongqing Li
Keyword(s):  
Concentration Gradient ◽  
Electroosmotic Flow ◽  
Channel Length ◽  
Concentration Profiles ◽  
Concentration Gradients ◽  
Simple Method ◽  
Gradient Generator ◽  
Gradient Generation ◽  
Diffusive Mixing ◽  
Linear Concentration

Creation of concentration gradients is important in the study of biological and chemical processes that are sensitive to concentration variations. This paper presents a simple method to generate a linear concentration gradient in electroosmotic flow in microchannels with converging and diverging geometries. The method is based on the enhanced diffusive mixing inside the microchannel. By varying the converging-diverging geometries, the degree of diffusive mixing can be controlled. Different concentration gradients can be obtained by varying the applied potential and the geometry. Concentration profiles with minimal axial variations can be achieved with a deviation of 7% and 3% over a channel length of 3mm and 1mm, respectively, for a 400μm wide microchannel. Although the underlying physics and mechanisms for creating concentration profiles in a converging-diverging microchannel are the same as a T-shaped micromixer, the converging-diverging microchannel can produce desired concentration profiles in a much shorter distance (shorter by a factor of 2∼3.5 compared to a T-shape mixer). A serially connected concentration gradient generator is also realized with the ability to generate two concentration gradient ranges in the same microchannel. Numerical simulations and experiments were carried out to investigate the factors contributed to the generation of the concentration gradients.

A Simple Device for Tissue Dehydration: Application of Concentration Gradient Generator

1976 ◽  
Vol 34 ◽  
pp. 338-339
Author(s):  
D. Goldfarb ◽  
K. Miyai ◽  
J. Hegenauer
Keyword(s):  
Electron Microscopy ◽  
Concentration Gradient ◽  
Chromatographic Separation ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Simple Device ◽  
Concentration Gradients ◽  
Gradient Generator ◽  
Mechanical Methods ◽  
General Configuration

We describe a simple device for dehydrating tissue for electron microscopy. Devices of the same general configuration are widely applied in chromatographic separation and density gradient centrifugation, which requires the generation of simple concentration gradients in a continuous rather than stepwise fashion. The application of this technique to tissue dehydration saves time and expense compared to manual and commercially available mechanical methods.The device consists of two parts: I. a gradient generator, and II. a tissue tray (Fig. 1). The upper part of the device consists of the concentration gradient generator, composed of reservoirs A, B, C and Delrin plate D. Torus A and cylinder B are connected by a channel E. Stopcock F permits independent filling of the reservoirs.

scholarly journals Optimal Design of Experiments for Hybrid Nonlinear Models, with Applications to Extended Michaelis–Menten Kinetics

2020 ◽  
Vol 25 (4) ◽  
pp. 601-616 ◽  
Author(s):  
Yuanzhi Huang ◽  
Steven G. Gilmour ◽  
Kalliopi Mylona ◽  
Peter Goos
Keyword(s):  
Optimal Design ◽  
Nonlinear Models ◽  
Nonlinear Least Squares ◽  
Kinetic Studies ◽  
Initial Reaction Rate ◽  
Industrial Applications ◽  
Design Criterion ◽  
Initial Reaction ◽  
Wide Range ◽  
Nonlinear Least Squares Estimation

Abstract Biochemical mechanism studies often assume statistical models derived from Michaelis–Menten kinetics, which are used to approximate initial reaction rate data given the concentration level of a single substrate. In experiments dealing with industrial applications, however, there are typically a wide range of kinetic profiles where more than one factor is controlled. We focus on optimal design of such experiments requiring the use of multifactor hybrid nonlinear models, which presents a considerable computational challenge. We examine three different candidate models and search for tailor-made D- or weighted-A-optimal designs that can ensure the efficiency of nonlinear least squares estimation. We also study a compound design criterion for discriminating between two candidate models, which we recommend for design of advanced kinetic studies. Supplementary materials accompanying this paper appear on-line

Complete experimental and theoretical characterization of nonlinear concentration gradient generator microfluidic device for analytical purposes

2021 ◽  
Vol 189 (1) ◽  
Author(s):  
Paulo Henrique Maciel Buzzetti ◽  
Maiara Mitiko Taniguchi ◽  
Nayara de Souza Mendes ◽  
Renata Corrêa Vicentino ◽  
Jean Halison de Oliveira ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Concentration Gradient ◽  
Gradient Generator ◽  
Theoretical Characterization

Nonlinear concentration gradients regulated by the width of channels for observation of half maximal inhibitory concentration (IC50) of transporter proteins

The Analyst ◽  
2015 ◽  
Vol 140 (16) ◽  
pp. 5557-5562 ◽  
Author(s):  
Yuta Abe ◽  
Koki Kamiya ◽  
Toshihisa Osaki ◽  
Hirotaka Sasaki ◽  
Ryuji Kawano ◽  
...  
Keyword(s):  
Abc Transporter ◽  
Concentration Gradient ◽  
Inhibitory Concentration ◽  
Concentration Gradients ◽  
Transporter Proteins ◽  
Gradient Generator

We determine a probable IC50 value of ABC transporter proteins by using a width-modulated nonlinear concentration gradient generator.

Influence of free convection on the diffusion current to a sphere in a laminar forced flow regime

1985 ◽  
Vol 50 (12) ◽  
pp. 2697-2714
Author(s):  
Arnošt Kimla ◽  
Jiří Míčka
Keyword(s):  
Asymptotic Expansion ◽  
Free Convection ◽  
Boundary Value Problem ◽  
Concentration Gradient ◽  
Empirical Formula ◽  
Convective Diffusion ◽  
Forced Flow ◽  
Diffusion Current ◽  
Wide Range ◽  
Free And Forced Convection

The formulation and solution of a boundary value problem is presented, describing the influence of the free convective diffusion on the forced one to a sphere for a wide range of Rayleigh, Ra, and Peclet, Pe, numbers. It is assumed that both the free and forced convection are oriented in the same sense. Numerical results obtained by the method of finite differences were approximated by an empirical formula based on an analytically derived asymptotic expansion for Pe → ∞. The concentration gradient at the surface and the total diffusion current calculated from the empirical formula agree with those obtained from the numerical solution within the limits of the estimated errors.

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