近日，《自然—通讯》（Nature Communications）期刊上发表了加拿大麦吉尔大学生物医学工程系的Mohammad Ameen Qasaimeh和David Juncker与蒙特利尔大学Ecole Polytechnique分校的Thomas Gervais等学者的研究成果。他们共同开发了新型浮动显微装置，可用来研究包括肿瘤细胞的形成、神经元如何在大脑发育中自我调节等细胞过程。
这个新型装置以四极（quadrupoles）或成对的相同物体为基础，两个正极和两个负极分别安排在正方形的四角，使它们之间出现一个力场。静电四极用于无线电天线中，磁四极则用来集中在粒子加速器中的带电粒子束。建造这个装置要在矽质的尖端蚀刻出四个约1平方厘米的小孔。两个来源孔（正极）会喷出细微的液体，而另外两个排水孔（负极）会将液体迅速吸回装置中。该装置的作用类似于吸尘器，能悬浮于活组织切片或者黏附细胞层的表面，根据不同的需要，送出所需的化学液体来刺激、探测、分离或杀死细胞。该装置还能建立化学浓度梯度变化的区域，以研究细菌和其他的细胞如何在体内到处活动，从而应用在许多细胞重要过程的体外研究中。(生物谷Bioon.com)
doi:10.1038/ncomms1471
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Microfluidic quadrupole and floating concentration gradient
Mohammad A. Qasaimeh, Thomas Gervais & David Juncker
The concept of fluidic multipoles, in analogy to electrostatics, has long been known as a particular class of solutions of the Navier-Stokes equation in potential flows; however, experimental observations of fluidic multipoles and of their characteristics have not been reported yet. Here we present a two-dimensional microfluidic quadrupole and a theoretical analysis consistent with the experimental observations. The microfluidic quadrupole was formed by simultaneously injecting and aspirating fluids from two pairs of opposing apertures in a narrow gap formed between a microfluidic probe and a substrate. A stagnation point was formed at the centre of the microfluidic quadrupole, and its position could be rapidly adjusted hydrodynamically. Following the injection of a solute through one of the poles, a stationary, tunable, and movable—that is, 'floating'—concentration gradient was formed at the stagnation point. Our results lay the foundation for future combined experimental and theoretical exploration of microfluidic planar multipoles including convective–diffusive phenomena.
