This paper presents theoretical analysis, design, simulation, fabrication and test of a microfluidic device ('Micro-hydrocyclone') for separation of micron and submicron size solid particles from liquid in a particle liquid mixture. A theoretical analysis of the micro-hydrocyclone is performed to understand the physics and develop suitable design models. The structure of the proposed device is designed based on the Bradley model, as it offers lower cut-size thus making it suitable for microfluidics applications. The operational parameters are derived from the dimensional group model. The particle separation process inside the micro-hydrocyclone is simulated by solving fluid flows using Navier-Stokes equations and particle dynamics using a Lagrangian approach in a Eulerian fluid. The influence of inlet velocity and density on separation efficiency is investigated. The device is fabricated with SU-8 photoresist on a PMMA substrate using a combination of photolithography and micro-milling. Experiments are performed to demonstrate particle-liquid separation using polystyrene microbeads suspended in PBS as the feed sample. The influence of inlet velocity and particle size on particle separation efficiency is measured and compared with that obtained from simulations and a good match was found. The proposed device can be easily integrated with micro-environments thus it is suitable for lab-on-chip and microsystems development. The device may have applications in chemical analysis, materials research, point-of-care, blood sample preparation and other biomedical applications.

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This paper presents a three-dimensional simulation of a micro hydrocyclone for the separation of micron sized particles from liquid in a particulated sample. A theoretical analysis is performed to demonstrate the working principle of the micro hydrocyclone and develop design models. The geometry of the proposed device is designed based on the Bradley model, since it offers a lower cut-size, thus making it suitable for microfluidics applications. The operational parameters of the hydrocyclone are derived from a dimensional group model. The particle separation process inside the micro hydrocyclone is simulated by solving fluid flows using Navier-Stokes equations and particle dynamics using the Lagrangian approach in a Eulerean fluid. First, the numerical model is validated by comparing the simulation results with the experimental results for a macroscale hydrocyclone reported in the literature. Then, the micro hydrocyclone is simulated and the simulation results are presented and discussed in the context of the functioning of the micro hydrocyclone. Finally, the effects of inlet velocity, vortex finder diameter, particle size, and density on the separation efficiency are investigated. The proposed device can be easily integrated with micro-environments; thus, is suitable for lab-on-chip and microsystems development.

A microfluidic system for rapid concentration, enumeration, and size based detection of microparticles is presented. The system includes a micro flow cytometer chip together with fluidics, optics and control on a single platform. The micro flow cytometer chip was designed, fabricated, and integrated with fluidics and optical fibers. The flow microchannel employs chevron structures at the top and bottom surfaces of the channel to achieve two-dimensional flow focusing. The system employs a cross-flow filter for sample concentration thus enabling enumeration and detection of microparticles even at low concentration levels (∼1.1 × 104/ml). A flow stabilizer chip based on the concept of a fluid chamber with a flexible membrane as the top wall was used to reduce flow pulsations within the fluidic system thus improving measurement accuracy. The excitation optical fiber is connected to a laser source and the collection fibers are connected to photomultiplier tubes (PMTs) for signal manipulation and conversion. Labview was used for data acquisition through a PC interface. The ability of the system for enumeration and size-based detection of microparticles was demonstrated using polystyrene microbeads suspended in PBS as the sample.

This paper presents theoretical analysis, design, fabrication and test of a microfluidic device (‘Micro hydrocyclone’) for separation of micron and sub-micron size solid particles from liquid in a particle-liquid mixture. A theoretical analysis of the micro hydrocyclone is performed to understand the physics and develop suitable design models. The structure of the proposed device is designed based on Bradley model, as it offers lower cut-size thus making it suitable for microfluidics applications. The operational parameters are derived from the dimensional group model. The device is fabricated with SU-8 photoresist on PMMA substrate using a combination of photolithography and micro-milling. Experiments are performed to demonstrate particle-liquid separation using polystyrene microbeads suspended in PBS as the feed sample. The influence of inlet velocity and particle size on particle separation efficiency is investigated. The proposed device can be easily integrated with micro-environments thus is suitable for lab-on-chip and microsystems development. The device may have applications in chemical analysis, materials research, point-of-care, blood sample preparation and other biomedical applications.