A Lamination Micro Mixer for .MU.-Immunomagnetic Cell Sorter

Abstract

We report successful design, fabrication and testing of a novel lamination micro mixer to be integrated in the micro-scale immunomagnetic cell sorter (µ-IMCS), which should be a key device for clinical applications of regenerative medicine. This paper covers, (i) the concept of µ-IMCS, (ii) design and fabrication of lamination mixer using MEMS technologies, (iii) numerical analysis for the evaluation of the mixer performance, and (iv) experimental evaluation of target cell capturing with the present micro mixer. In order to reduce the sedimentation loss of the cells and the magnetic beads, the conduits in the mixer are designed in such a way that the stream is turned over 180 degree. It is found in the CFD analysis that the present lamination mixer realizes better mixing and lower sedimentation loss than the one without rotation in the previous study. Experiments reveal that the cell capture rate is (i) increased by up to 8.6 times compared with that in a straight channel, and (ii) decreased with decreasing the residence time. It is also demonstrated in a preliminary experiment that CD31 expressions of HUVEC and hMSC obtained with the present micro mixer are in good agreement with the data obtained with a conventional cell sorting system. Therefore, the present mixer should be a viable component in a µ-IMCS.

Performance Assessment and Improvement of a Spilt-and-Recombine Micromixer for Immunomagnetic Cell Sorting

“…We consider an SAR micromixer proposed by Tan et al, (9) as shown in Fig. 2(a), which has a three-layer structure.…”

“…On the other hand, the passive micromixers use the geometrical structure of the conduit, so that the stretching and folding of fluids are induced by the chaotic advection (5,6) or the lamination of interfaces. (7)(8)(9)(10) The mixers using the latter mechanism, which are called lamination mixers or split-and-recombine (SAR) mixers, can simplify the fabricating and operating processes as compared to the active mixers. In order to optimize the design of micro mixing devices, the flow characteristics and the resulting mixing performance should be investigated in detail.…”

“…(10) They reported that a cross-SAR configuration accelerates the mixing by 4.4 times as compared to the flow in a straight channel with the same pressure drop. The objective of the present study is to numerically investigate the relationship between the particle motion and the performance of another type of SAR micromixer (9) and to propose an improved design based on the knowledge obtained from the simulation.…”

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AbstractPerformance of a split-and-recombine micromixer (Tan et al, 2005) is assessed by means of numerical simulation. The micromixer is designed for micro cell sorting systems using immunomagnetic beads, of which working principle is lamination of fluid layers.

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“…Based on the observation, an improved mixer arrangement is proposed. While the original arrangement proposed by Tan et al (2005) was to simply connect identical unit-mixers, the present arrangement is to alternately connect the original unit-mixer and one with the mirrored geometry. With this modified arrangement, the unmixed region is suppressed and better mixing is achieved.…”