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Microf Low Cytometer: Hydrodynamic Focusing and Separation of Sample Stream
| Content Provider | Semantic Scholar |
|---|---|
| Author | Hashemi, Nastaran Ligler, Frances S. |
| Copyright Year | 2010 |
| Abstract | Using grooves in the walls of a microchannel and two sheath streams, we have passively focused a sample stream in the center of the microchannel for optical analysis. Even though the sample stream is completely surrounded by sheath fluid, reversing the orientation of the grooves in the channel walls returns the sample stream to its original position with respect to the sheath streams. The use of this sheathing technique has already been demonstrated in a sensitive microflow cytometer; the unsheathing capability now provides the opportunity to recover particles from the sensor with minimal dilution or to recycle the sheath fluid for long-term unattended operation. The ability to reverse focused laminar flows opens a variety of options for combining target transport, processing and analysis procedures. INTRODUCTION Flow cytometry is used to count and characterize cells and particles. In the traditional design, the sample stream exiting a small channel is introduced into the center of a larger channel containing sheath fluid. Then the larger channel constricts to force the cells or particles to travel in single file along a fixed and precise trajectory within the flow channel. Since the cells are following the same path, they all have the same velocity and can be interrogated with low variance. Over the last decades, researchers in the microfluidics community have focused on using microfluidics to create microflow cytometers with very small footprints. Furthermore, hydrodynamic focusing of one laminar stream by another without mixing has inspired new approaches for separations, optical components, biosensors, and cell analysis.[3,5,6,7,8,9] Creating sheathed flow by placing a small tube inside a larger one is hard to microfabricate. Jacobson and Ramsey used a cross intersection to create sheathed flow. [10] Later on, Blankenstein and Larsen used pressure-driven flow for the interrogation of polystyrene beads for cytometry. [11] Howell et al. presented two designs that can create fully sheathed flow in a microdevice. In the first design, a T-junction directed the sample and sheath streams side-by-side into the channel. A set of straight diagonal grooves on the top and bottom of the channel wrapped the sample fluid with sheath fluid. Passing through more grooves, the sheath fluid moved toward the far side of the sample stream and sample stream became focused more toward the center of the channel. Fig. 1A shows numerical simulation of this design using Tiny-3D.[23] The chips were made in polymethyl methacrylate (PMMA) using a Haas Minimill to experimentally demonstrate the sheathing process. Channel dimensions were 450 μm wide by 150 μm deep. The grooves were 150 μm wide by 75 μm deep at 45 ◦ relative to the axis of the channel. Fig. 1B shows the dye-labeled sample stream is brought to the center of the channel by 5 pairs of stripes. In the other design, shown in Fig. 2, the sheath solution was divided equally between the two inlets of a Tintersection to position the sample stream in the center of the channel. A set of chevrons cut into the top and Proceedings of the ASME 2010 International Mechanical Engineering Congress & Exposition IMECE2010 November 12-18, 2010, Vancouver, British Columbia, Canada |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://web.me.iastate.edu/hashemi/Proceeding/Microflow%20Cytometer%20Hydrodynamic%20Focusing%20and%20Separation%20of%20Sample%20Stream.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Apache Axis Audio feedback Axis vertebra Bead Dosage Form Biosensors Columbia (supercomputer) Computer simulation Dimensions Dimercaprol Dyes Experiment Flow Cytometry Greater Hydrodynamics Inspiration function Large Methacrylates Microfluidics Optical Devices Polyhydroxyethyl Methacrylate Polymethyl Methacrylate Polystyrenes Precedence effect P–n junction Recycling Reversing: Secrets of Reverse Engineering Sample Variance Streaming media Stripes Tracer Velocity (software development) Walls of a building automated flow cytometers |
| Content Type | Text |
| Resource Type | Article |
