Particle Focusing in Staged Inertial Microfluidic Devices for Flow Cytometry (original) (raw)
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Microflow Cytometers with Integrated Hydrodynamic Focusing
Sensors, 2013
This study demonstrates the suitability of microfluidic structures for high throughput blood cell analysis. The microfluidic chips exploit fully integrated hydrodynamic focusing based on two different concepts: Two-stage cascade focusing and spin focusing (vortex) principle. The sample-A suspension of micro particles or blood cells-is injected into a sheath fluid streaming at a substantially higher flow rate, which assures positioning of the particles in the center of the flow channel. Particle velocities of a few m/s are achieved as required for high throughput blood cell analysis. The stability of hydrodynamic particle positioning was evaluated by measuring the pulse heights distributions of fluorescence signals from calibration beads. Quantitative assessment based on coefficient of variation for the fluorescence intensity distributions resulted in a value of about 3% determined for the micro-device exploiting cascade hydrodynamic focusing. For the spin focusing approach similar values were achieved for sample flow rates being 1.5 times lower. Our results indicate that the performances of both variants of hydrodynamic focusing suit for blood cell differentiation and counting. The potential of the micro flow cytometer is demonstrated by detecting immunologically labeled CD3 positive and CD4 positive T-lymphocytes in blood.
A Novel Hydrodynamic Focusing Microdevice for Flow Cytometry Applications
Iranian Journal of Science and Technology: Transactions of Mechanical Engineering
Hydrodynamic focusing is one of the most utilized techniques in microfluidics. Its applications have been employed in a wide variety of biological analyses including on-chip flow cytometry, single molecule detection, and laminar mixers. In the present study, a new hydrodynamic focusing microdevice for flow cytometry applications is presented and numerically investigated. In the proposed microdevice, the sample fluid is compressed both in vertical and horizontal directions simultaneously by radial sheath flows injected within flow cytometer through one ring. The microdevice configuration is optimized and effective parameters on stream distribution are investigated. In addition, in order to observe hydrodynamic focusing phenomena, particles trajectories are studied. Moreover, results of the proposed model are compared with the previous one in order to verify that the performance of the present model is more efficient.
Biomicrofluidics, 2012
In this work, we demonstrate an integrated, single-layer, miniature flow cytometry device that is capable of multi-parametric particle analysis. The device integrates both particle focusing and detection components on-chip, including a "microfluidic drifting" based three-dimensional (3D) hydrodynamic focusing component and a series of optical fibers integrated into the microfluidic architecture to facilitate onchip detection. With this design, multiple optical signals (i.e., forward scatter, side scatter, and fluorescence) from individual particles can be simultaneously detected. Experimental results indicate that the performance of our flow cytometry chip is comparable to its bulky, expensive desktop counterpart. The integration of on-chip 3D particle focusing with on-chip multi-parametric optical detection in a singlelayer, mass-producible microfluidic device presents a major step towards low-cost flow cytometry chips for point-of-care clinical diagnostics. V
Biomicrofluidics, 2020
We present design, characterization, and testing of an inexpensive, sheath-flow based microfluidic device for three-dimensional (3D) hydrodynamic focusing of cells in imaging flow cytometry. In contrast to other 3D sheathing devices, our device hydrodynamically focuses the cells in a single-file near the bottom wall of the microchannel that allows imaging cells with high magnification and low working distance objectives, without the need for small device dimensions. The relatively large dimensions of the microchannels enable easy fabrication using less-precise fabrication techniques, and the simplicity of the device design avoids the need for tedious alignment of various layers. We have characterized the performance of the device with 3D numerical simulations and validated these simulations with experiments of hydrodynamic focusing of a fluorescently dyed sample fluid. The simulations show that the width and the height of the 3D focused sample stream can be controlled independently by varying the heights of main and side channels of the device, and the flow rates of sample and sheath fluids. Based on simulations, we also provide useful guidelines for choosing the device dimensions and flow rates for focusing cells of a particular size. Thereafter, we demonstrate the applicability of our device for imaging a large number of RBCs using brightfield microscopy. We also discuss the choice of the region of interest and camera frame rate so as to image each cell individually in our device. The design of our microfluidic device makes it equally applicable for imaging cells of different sizes using various other imaging techniques such as phasecontrast and fluorescence microscopy.
Microfluidics for flow cytometric analysis of cells and particles
Physiological …, 2005
This review describes recent developments in microfabricated flow cytometers and related microfluidic devices that can detect, analyze, and sort cells or particles. The high-speed analytical capabilities of flow cytometry depend on the cooperative use of microfluidics, optics and electronics. Along with the improvement of other components, replacement of conventional glass capillary-based fluidics with microfluidic sample handling systems operating in microfabricated structures enables volume-and power-efficient, inexpensive and flexible analysis of particulate samples. In this review, we present various efforts that take advantage of novel microscale flow phenomena and microfabrication techniques to build microfluidic cell analysis systems.
Universally applicable three-dimensional hydrodynamic microfluidic flow focusing
Lab on a Chip, 2013
We have demonstrated a microfluidic device that can not only achieve three-dimensional flow focusing but also confine particles to the center stream along the channel. The device has a sample channel of smaller height and two sheath flow channels of greater height, merged into the downstream main channel where 3D focusing effects occur. We have demonstrated that both beads and cells in our device display significantly lower CVs in velocity and position distributions as well as reduced probability of coincidental events than they do in conventional 2D-confined microfluidic channels. The improved particle confinement in the microfluidic channel is highly desirable for microfluidic flow cytometers and in fluorescence-activated cell sorting (FACS). We have also reported a novel method to measure the velocity of each individual particle in the microfluidic channel. The method is compatible with the flow cytometer setup and requires no sophisticated visualization equipment. The principles and methods of device design and characterization can be applicable to many types of microfluidic systems.
Hydrodynamic focusing is an important method used in microfluidics cell sorting devices. It is a technique that allows two sheath fluids to conflow at different velocities to obtain the focusing of sample fluid. The objective of hydrodynamic focusing is to make sure the particle arrives one by one at detection source. Simulation is done using COMSOL Multyphysics software to observe particle trajectories in micro flow cytometer with circular and rectangular cross-section. The density and sizes of the particles is similar to protein particles properties. Normal inflow velocity fot sheath channel is 800µm/s and normal inflow velocity for sample channel is 150µm/s. At The beginning of the experiment, circular flow cytometer was expected to have better hydrodynamic focusing effect and better particle trajectories. However, after the simulation is done the results show that particle trajectories in rectangular channel are better. Reduce channel height is one of the factor that enables particle to focus in the middle of the channel for the rectangular shape channel device.
Effect of Microchannel Sizes on 3D Hydrodynamic Focusing of a Microflow Cytometer
Hydrodynamic focusing is an important method used in microfluidics cell sorting devices. A design of flow cytometer has been developed and simulated using COMSOL Multyphysics software. The device is capable of creating a self-aligned stream by manipulating the flow rate, Q in both sheath channel. The objective of this research is to study the effect of channel size variation on the fluid flow in the micro flow cytometer device. The flow rate ratio Qs/Qi is applied in order find the best flow rate ratio value between sheath channel and sample channel. Simulated results showed that when Qs is smaller than Qi, the stream size is bigger and the length of the stream is longer. However, Qs is equal to Qi, the stream becomes smaller and the length of the stream is shorter. Similary, when Qs is bigger than Qi, the stream becomes smaller and shorter. The results showed that fluid flow is better when the size of the channel is bigger.