Single-layer planar on-chip flow cytometer using microfluidic drifting based three-dimensional (3D) hydrodynamic focusing

Lab on a Chip ◽  
2009 ◽  
Vol 9 (11) ◽  
pp. 1583 ◽  
Author(s):  
Xiaole Mao ◽  
Sz-Chin Steven Lin ◽  
Cheng Dong ◽  
Tony Jun Huang
Keyword(s):  
Three Dimensional ◽  
Single Layer ◽  
Flow Cytometer ◽  
Hydrodynamic Focusing ◽  
Chip Flow ◽  
On Chip

Three-Dimensional Electrokinetic Focusing in a Planar Microstructure

2005 ◽  
Author(s):  
Jeffrey T. Coleman ◽  
Bob M. Lansdorp ◽  
David Sinton
Keyword(s):  
Three Dimensional ◽  
Optical Measurements ◽  
Two Dimensional ◽  
Hydrodynamic Focusing ◽  
Cross Sectional ◽  
Local Flow ◽  
Surface Patches ◽  
Sample Stream ◽  
Chip Flow ◽  
On Chip

Hydrodynamic focusing is commonly employed to reduce the cross-sectional area of a microfluidic sample stream. Two-dimensional focusing is achieved by combining a central sample stream with a buffer sheathing flow on adjacent sides of a standard microfluidic cross chip. This method of on-chip hydrodynamic focusing is the most common, perhaps due to the relative ease and popularity of planar microfluidic chip fabrication methods. The application of two-dimensional focusing to on-chip flow cytometry is limited for two reasons: Firstly, the degree of focusing obtained is limited by the microchannel depth. Secondly, many biological analytes adhere to channel walls mitigating the optical measurements. Three-dimensional focusing can both increase the focus intensity, and minimize interaction between the analyte stream and the channel walls in the viewed region. In this work, a new method is presented for obtaining three-dimensional hydrodynamic focusing on a planar microfluidic geometry using strategically placed surface charge patches. Numerical simulations are employed to show the concentration profiles resulting from the local flow circulations induced by the surface patches in an electrokinetically-driven flow.

scholarly journals 3D Hydrodynamic Focusing in Microscale Optofluidic Channels Formed with a Single Sacrificial Layer

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 349 ◽  
Author(s):  
Erik S. Hamilton ◽  
Vahid Ganjalizadeh ◽  
Joel G. Wright ◽  
Holger Schmidt ◽  
Aaron R. Hawkins
Keyword(s):  
Cross Sections ◽  
Optical Waveguides ◽  
Sacrificial Layer ◽  
Three Dimensional ◽  
Single Layer ◽  
Detection Sensitivity ◽  
Low Flow ◽  
Hydrodynamic Focusing ◽  
Induced Focusing ◽  
Pressure Driven Flow

Optofluidic devices are capable of detecting single molecules, but greater sensitivity and specificity is desired through hydrodynamic focusing (HDF). Three-dimensional (3D) hydrodynamic focusing was implemented in 10-μm scale microchannel cross-sections made with a single sacrificial layer. HDF is achieved using buffer fluid to sheath the sample fluid, requiring four fluid ports to operate by pressure driven flow. A low-pressure chamber, or pit, formed by etching into a substrate, enables volumetric flow ratio-induced focusing at a low flow velocity. The single layer design simplifies surface micromachining and improves device yield by 1.56 times over previous work. The focusing design was integrated with optical waveguides and used in order to analyze fluorescent signals from beads in fluid flow. The implementation of the focusing scheme was found to narrow the distribution of bead velocity and fluorescent signal, giving rise to 33% more consistent signal. Reservoir effects were observed at low operational vacuum pressures and a balance between optofluidic signal variance and intensity was achieved. The implementation of the design in optofluidic sensors will enable higher detection sensitivity and sample specificity.

An auxiliary approach to the experimental study on chip control: A kinematically simulated test

1998 ◽  
Vol 212 (2) ◽  
pp. 159-166 ◽  
Author(s):  
N Fang
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Cutting Tools ◽  
Three Dimensional ◽  
Experimental Period ◽  
Machining Processes ◽  
Chip Breaking ◽  
Chip Flow ◽  
Simulated Test ◽  
On Chip

Traditionally, cutting tools made of sintered carbides or high-speed steels are used to cut a variety of metal materials in the experimental study on chip control. One of the existing problems is that, in most cases, it is difficult to make, in a laboratory, cutting tools with a three-dimensionally shaped chip breaking groove for use in the follow-up experiments. Turning to tool manufacturers, who use the powder metallurgy techniques of tool making for help, usually leads to a long experimental period and high cost. An auxiliary approach to the experimental study on chip control, called a kinematically simulated test (KST), is proposed in this present work to overcome the above shortcoming of the traditional method employed in the experimental study on chip control. A plexiglass-made cutting tool is employed to cut a commercially available paraffin wax to simulate some kinematic phenomena (such as chip flow and chip curl) which take place during practical machining processes. After the applied range of KST has been illustrated, two examples of applying KST are given. One is the application of KST to chip flow research. The other is optimizing the geometry of the chip breaking groove of a tool insert by means of KST. Both examples involve the making of the chip breaking grooves with the three-dimensional shape and geometry.

Three-Dimensional Microfluidic Focusing With Surface Charge Patterning

2005 ◽  
Author(s):  
Jeffrey T. Coleman ◽  
David Sinton
Keyword(s):  
Surface Charge ◽  
Three Dimensional ◽  
Memory Storage ◽  
Surface Patch ◽  
Hydrodynamic Focusing ◽  
Cross Sectional ◽  
Lab On Chip ◽  
Surface Patches ◽  
Sectional Surface ◽  
On Chip

Electrokinetically-driven flow circulations resulting from heterogeneous surface patches have previously been employed to improve mixing in microchannels. Here, numerical simulations demonstrate local in-channel hydrodynamic focusing through the use of strategically-patterned surface charge. Presented first is the case of a single straight channel with an axially-localized cross-sectional surface patch (ring). The surface patch exhibits a zeta potential equal in magnitude to the native microchannel surface but opposite in sign. The unsteady species transport in the presence of the electrokinetically-induced circulations is modelled, and a mean residence time is quantified. In general, residence times indicate the potential application of these circulations to microfluidic-based memory storage. Next, an improved focusing process for pinched-injection is demonstrated that exploits non-uniform surface patches. Lastly, surface patches are applied to enhance stream focusing in the microfluidic cross geometry. It is demonstrated that with this technique three-dimensional hydrodynamic focusing can be achieved in a single planar microfluidic structure. In one case, the microfluidic fluid stream was constrained to the centre of the channel and focused to 12% of its original cross-sectional area. Extensions of this work are discussed, as are the microfabrication and surface modification processes required for lab-on-chip implementation of these numerically simulated processes.

Universally applicable three-dimensional hydrodynamic focusing in a single-layer channel for single cell analysis

2018 ◽  
Vol 10 (28) ◽  
pp. 3489-3497 ◽  
Author(s):  
Yingying Zhao ◽  
Qin Li ◽  
Xiaoming Hu
Keyword(s):  
Single Cell ◽  
Single Cell Analysis ◽  
Three Dimensional ◽  
Single Layer ◽  
Optical Systems ◽  
Cell Analysis ◽  
Hydrodynamic Focusing ◽  
Integrated Optical ◽  
Microfluidic Structure

A microfluidic cytometer which integrated 3D hydrodynamic focusing and integrated optical systems on a single-layer microfluidic structure was demonstrated.

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