A microfluidic platform for micromixing, trapping and real-time monitoring of single cells via microvortices
Date Issued
2009
Date
2009
Author(s)
Lin, Cheng-Ming
Abstract
A quantified cell-based analysis system requires the ability to locate live cells gently without changing their natural behavior. We describe a new hydrodynamic method via a secondary, steady streaming flow to trap suspended bioparticles and enhance flow mixing. Generation of the streaming flow utilized an in-plane resonating microplate (100 μm × 100 μm × 1.2 μm) actuated by Lorentz law. Either one of the two non-linear time-mean flow structures is feasible for the finite plate resonated in liquid: (1) two-dimensional (2D), small-scale, counter-rotating microvortices, or (2) three-dimensional, large-scale, recirculating flow. esults consist of kinematics of microvortices, efficacy in mixing enhancement, trapping and release of bioparticles, cell viability study, and monitoring of single trapped cell via immuno-staining. ixing performance due to the 3D circulating flow was studied and characterized. The 3D recirculating flow is shown to enhance mixing – majority of mixing (X90) is reached within 1mm. The 2D counter-rotating microvortices rotate at 0-6 Hz corresponding to 2-9 Vpp (peak-to-peak) excitation. At a particular rate of rotation (2-7 Vpp tested), a bioparticle is trapped until the background flow exceeds a limit. The flow limit increases with the rate of rotation, which defines the trap/release force boundary over the range of operation. rapping and releasing of 10μm polystyrene beads, human embryonic kidney (HEK) cells, red blood cells (RBCs), Jurkat cells and IgG antibodies were demonstrated. The trap/release boundary is 12(+-)2.0 pN for cell-size bioparticles and 160(+-)50 fN for antibodies. Trapping of RBCs demonstrated microvortices’ ability for non-spherical cells. Cell viability was studied via HEK cells that were trapped for 30 minutes and shown to be viable. esignedly, a platform was combined a micromixer, providing 3D circulating flow, in the upstream with four trappers in the downstream. Single Jurkat cells were tested by immunofluorescent staining with CD45 antibodies (conjugated to R-phycoerythrin) under a real-time observation. Data show only the trapped cells subjected to the immunofluorescent treatment can express red fluorescence. This hydrodynamically controlled approach to trap a wide range of bioparticles and enhance mixing should be useful as a microfluidic device for cellular and sub-cellular bioassay applications. uture development of the technique might include various bioassay platforms, such as cell culture of suspended cells after being trapped, study on interaction between single cell and flow dynamics, drug screening, and enrichment of low volume fraction bioparticle studies.
Subjects
Vortices
Circulating flow
Oscillatory plate
Lorentz force
Cell trapping
Micromixer
Type
thesis
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