Yi Wang

Columbia University, New York City, NY, United States

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Publications (14)27.8 Total impact

  • Yao Zhou, Yi Wang, Qiao Lin
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    ABSTRACT: This paper presents a novel microfluidic device that exploits magnetic manipulation for integrated capture and isolation of microparticles in continuous flow. The device, which was fabricated from poly(dimethylsiloxane) (PDMS) by soft-lithography techniques, consists of an incubator and a separator integrated on a single chip. The incubator is based on a novel scheme termed target acquisition by repetitive traversal (TART), in which surface-functionalized magnetic beads repetitively traverse a sample to seek out and capture target particles. This is accomplished by a judicious combination of a serpentine microchannel geometry and a time-invariant magnetic field. Subsequently, in the separator, the captured target particles are isolated from nontarget particles via magnetically driven fractionation in the same magnetic field. Due to the TART incubation scheme that uses a corner-free serpentine channel, the device has no dead volume and allows minimization of undesired particle or magnetic-bead retention. Single-chip integration of the TART incubator with the magnetic-fractionation separator further allows automated continuous isolation and retrieval of specific microparticles in an integrated manner that is free of manual off-chip sample incubation, as often required by alternative approaches. Experiments are conducted to characterize the individual incubation and separation components, as well as the integrated device. The device is found to allow 90% of target particles in a sample to be captured and isolated and 99% of nontarget particles to be eliminated. With this high separation efficiency, along with excellent reliability and flexibility, the device is well suited to sorting, purification, enrichment, and detection of micro/nanoparticles and cells in lab-on-a-chip systems.
    Journal of Microelectromechanical Systems 09/2010; · 2.13 Impact Factor
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    ABSTRACT: This paper proposes novel microfluidic concentration gradient generator (CGG) devices that are capable of constructing complex profiles of chemical concentrations by laterally combining the constituent profiles (e.g., linear and bell-shaped) generated in simple Y- or psi-shaped mixers. While the majority of currently existing CGG devices are based on complete mixing of chemical species, our design harnesses partial diffusive mixing in multi-stream laminar flow, and hence, features simple network structures and enhanced device reliability. An iterative simulation approach that incorporates our previous system-level models of CGG networks is developed to locate best-matched combinations of geometrical and operating parameters (e.g., inlet flow rates and inlet sample concentrations) for the device design. Microfluidic CGG chips are fabricated and experimentally characterized using optimal layout and operating conditions selected by the design process. The experimental results not only serve as a benchmark for model verification but also establish the feasibility of concentration gradient generation based on partial mixing for a variety of microfluidic applications.
    Lab on a Chip 06/2009; 9(10):1439-48. · 5.70 Impact Factor
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    ABSTRACT: This paper presents a systematic modeling methodology for microfluidic concentration gradient generators. The generator is decomposed into a system of microfluidic elements with relatively simple geometries. Parameterized models for such elements are analytically developed and hold for general sample concentration profiles and arbitrary flow ratios at the element inlet; hence, they are valid for concentration gradient generators that rely on either complete or partial mixing. The element models are then linked through an appropriate set of parameters embedded at the element interfaces. This yields a systematic, lumped-parameter representation of the entire generator in terms of a network of gradient-generation elements. The system model is verified by numerical analysis and experimental data and accurately captures the overall effects of network topologies, element sizes, flow rates and reservoir sample concentrations on the generation of sample concentration gradient. Finally, this modeling methodology is applied to propose a novel and compact microfluidic device that is able to create concentration gradients of complex shapes by juxtaposing simple constituent profiles along the channel width.
    Journal of Micromechanics and Microengineering 08/2006; 16(10):2128. · 1.79 Impact Factor
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    ABSTRACT: This paper presents a systematic modeling and design methodology for microfluidic concentration gradient generators. The generator is decomposed into a system of microfluidic elements with relatively simple geometries. Parameterized models for such elements are analytically developed and hold for general sample concentration profiles and arbitrary flow ratios at the element inlet, hence they are valid for concentration gradient generators that rely on both complete and partial mixing. The element models are then linked through an appropriate set of parameters embedded at the element interfaces to construct a lumped-parameter and systematic representation of the entire generator network. The system model is verified by numerical analysis and experimental data and accurately captures the overall effects of network topologies, element sizes, flow rates and reservoir sample concentrations on the generation of sample concentration gradient. Finally, this modeling methodology is applied to propose a novel and compact microfluidic device that is able to create concentration gradients of complex shapes by juxtaposing simple constituent profiles along the channel width
    Nano/Micro Engineered and Molecular Systems, 2006. NEMS '06. 1st IEEE International Conference on; 02/2006
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    ABSTRACT: This paper presents composable behavioral models and a schematic-based simulation methodology to enable top-down design of electrokinetic (EK) lab-on-a-chip (LoC). Complex EK LoCs are shown to be decomposable into a system of elements with simple geometry and specific function. Parameterized and analytical models are developed to describe the electric and biofluidic behavior within each element. Electric and biofluidic pins at element terminals support the communication between adjacent elements in a simulation schematic. An analog hardware description language implementation of the models is used to simulate LoC subsystems for micromixing and electrophoretic separation. Both direct current (dc) and transient analysis can be performed to capture the influence of system topology, element sizes, material properties, and operational parameters on LoC system performance. Accuracy (relative error generally less than 5%) and speedup$(≫hbox100times)$of the schematic-based simulation methodology are demonstrated by comparison to experimental measurements and continuum numerical simulation.
    IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 01/2006; 25:258-273. · 1.09 Impact Factor
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    ABSTRACT: This paper presents a model for the efficient and accurate simulations of laminar diffusion-based complex electrokinetic passive micromixers by representing them as a system of mixing elements of relatively simple geometry. Parameterized and analytical models for such elements are obtained, which hold for general sample concentration profiles and arbitrary flow ratios at the element inlet. A lumped-parameter and system-level model is constructed for a complex micromixer, in which the constituent mixing elements are represented by element models, in such a way that an appropriate set of parameters are continuous at the interface between each pair of adjacent elements. The system-level model, which simultaneously computes electric circuitry and sample concentration distributions in the entire micromixer, agrees with numerical and experimental results, and offers orders-of-magnitude improvements in computational efficiency over full numerical simulations. The efficiency and usefulness of the model is demonstrated by exploring a number of laminar diffusion based mixers and mixing networks that occur in practice.
    Lab on a Chip 09/2005; 5(8):877-87. · 5.70 Impact Factor
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    ABSTRACT: This paper presents a schematic-based and system-oriented modeling and simulation framework to enable top-down designs of multifunctional biofluidic lab-on-a-chip systems. An analog hardware description language (Verilog-A) is used to integrate parameterized and closed-form models of elements with different functionalities (e.g., mixing, reaction, injection and separation). Both DC and transient analysis are performed on a practical competitive immunoassay chip to capture the influence of topology, element sizes, material properties and operational parameters on the chip performance. Accuracy (relative error generally less than 5%) and speedup (>100×) of the schematic-based simulation is obtained by comparison to continuum numerical simulation as well as experimental measurements. A redesign of the original LoC device using our framework to improve bio-analysis efficiency and minimize chip-area has been demonstrated.
    Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05. The 13th International Conference on; 07/2005
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    ABSTRACT: This paper presents an analytical and parameterized model for analyzing the effects of Joule heating on analyte dispersion in electrophoretic separation microchannels. We first obtain non-uniform temperature distributions in the channel resulting from Joule heating, and then determine variations in electrophoretic velocity, based on the fact that the analyte's electrophoretic mobility depends on the buffer viscosity and hence temperature. The convection-diffusion equation is then formulated and solved in terms of spatial moments of the analyte concentration. The resulting model is validated by both numerical simulations and experimental data, and holds for all mass transfer regimes, including unsteady dispersion processes that commonly occur in microchip electrophoresis. This model, which is given in terms of analytical expressions and fully parameterized with channel dimensions and material properties, applies to dispersion of analyte bands of general initial shape in straight and constant-radius-turn channels. As such, the model can be used to represent analyte dispersion in microchannels of more general shape, such as serpentine- or spiral-shaped channels.
    Lab on a Chip 01/2005; 4(6):625-31. · 5.70 Impact Factor
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    ABSTRACT: This paper presents a system-oriented model for analyzing the dispersion of electrophoretic transport of charged analyte molecules in a general-shaped microchannel, which is represented as a system of serially connected elemental channels of simple geometry. Parameterized analytical models that hold for analyte bands of virtually arbitrary initial shape are derived to describe analyte dispersion, including both the skew and broadening of the band, in elemental channels. These models are then integrated to describe dispersion in the general-shaped channel using appropriate parameters to represent interfaces of adjacent elements. This lumped-parameter system model offers orders-of-magnitude improvement in computational efficiency over full numerical simulations, and is verified by results from experiments and numerical simulations. The model is used to perform a systematic parametric study of serpentine channels consisting of a pair of complementary turn microchannels, and the results indicate that dispersion in a particular turn can contribute to either an increase or decrease of the overall band broadening. The efficiency and accuracy of the system model is further demonstrated by its application to general-shaped channels that occur in practice, including a serpentine channel with multiple complementary turns and a multi-turn spiral-shaped channel. The results indicate that our model is an accurate and efficient simulation tool useful for designing optimal electrophoretic separation microchips.
    Lab on a Chip 11/2004; 4(5):453-63. · 5.70 Impact Factor
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    ABSTRACT: This paper presents an analytical and parameterized model for analyzing the effects of Joule heating on analyte dispersion in electrophoretic separation microchannels. We first obtain non-uniform temperature distributions in the channel resulting from Joule heating, and then determine variations in electrophoretic velocity, based on the fact that the analyte’s electrophoretic mobility depends on the buffer viscosity and hence temperature. The convection-diffusion equation is then formulated and solved in terms of spatial moments of the analyte concentration. The resulting model is validated by both numerical simulations and experimental data, and holds for all mass transfer regimes, including unsteady dispersion processes that commonly occur in microchip electrophoresis. This model, which is given in terms of analytical expressions and fully parameterized with channel dimensions and material properties, applies to dispersion of analyte bands of general initial shape in straight and constant-radius-turn channels. As such, the model can be used to represent analyte dispersion in microchannels of more general shape, such as serpentine- or spiral-shaped channels.
    ASME 2004 International Mechanical Engineering Congress and Exposition; 01/2004
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    ABSTRACT: This paper presents a model for Joule heating induced analyte dispersion in electrophoretic separation channels with a rectangular cross section. The model is in closed form and captures the effect of cross-sectional geometry. Three-dimensional numerical simulations are performed to satisfactorily verify the model, which can be used to accurately predict the performance of high speed electrophoretic separations.
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    ABSTRACT: This paper presents an analytical Joule heating dispersion model for rectangular microchannels. The model holds in all convection-diffusion mass transfer regimes and captures the effects of cross-sectional shape and separation time on JH induced dispersion. The model is verified by three-dimensional numerical simulation and agrees with experimental data from microchip electrophoresis.
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    Article: micromixers
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    ABSTRACT: This paper presents a model for the efficient and accurate simulations of laminar diffusion-based complex electrokinetic passive micromixers by representing them as a system of mixing elements of relatively simple geometry. Parameterized and analytical models for such elements are obtained, which hold for general sample concentration profiles and arbitrary flow ratios at the element inlet. A lumped-parameter and system-level model is constructed for a complex micromixer, in which the constituent mixing elements are represented by element models, in such a way that an appropriate set of parameters are continuous at the interface between each pair of adjacent elements. The system-level model, which simultaneously computes electric circuitry and sample concentration distributions in the entire micromixer, agrees with numerical and experimental results, and offers orders-of-magnitude improvements in computational efficiency over full numerical simulations. The efficiency and usefulness of the model is demonstrated by exploring a number of laminar diffusion based mixers and mixing networks that occur in practice.
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    ABSTRACT: This paper presents composable and parameterized electrokinetic passive mixing models that are the first to simultaneously simulate both electric and concentration (partial mixing) networks at the system level and enable the design of efficient and compact mixers for integrated Micro-TAS. Model validity is verified by comparison to numerical data.

Publication Stats

107 Citations
27.80 Total Impact Points

Institutions

  • 2009–2010
    • Columbia University
      • Department of Mechanical Engineering
      New York City, NY, United States
  • 2006–2009
    • CFDRC - CFD Research Corporation
      Huntsville, Alabama, United States
  • 2004–2005
    • Carnegie Mellon University
      • Department of Mechanical Engineering
      Pittsburgh, PA, United States