三角形截面微流道中粒子惯性聚焦分离特性

Characterization of particles inertial focusing and separation in microchannel with triangular cross-section

为实现不同尺寸微粒的高效分离,提出一种三角形截面微流道的惯性微流控芯片,研究了微粒在流道中的聚焦与分离特性。首先,设计一种直角三角形截面结构的螺旋流道,采用精密微铣削工艺加工了流道的铝材模具,利用倒模与等离子清洗键合工艺制备微流控芯片。接着,配制三种尺寸(6μm,10μm和15μm)的荧光微粒悬浮液,利用高速摄像机和荧光显微镜拍摄粒子在流道中的运动轨迹,观测不同悬浮液流量时微粒的聚焦效果。最后,对微粒聚焦轨迹图像进行堆叠分析,研究微粒的惯性聚焦与分离行为。结果表明:随着悬浮液流量的增大,6μm粒子逐渐聚焦并向流道外壁面迁移,而10μm和15μm聚焦粒子束则向流道中心迁移。当悬浮液流量为1.5 mL/min时,6μm和15μm混合粒子实现了100%精确分离。研究结果表明,三角形截面螺旋流道可产生强偏置二次流,使不同尺寸微粒实现高效、精确分离,为细胞精准操控提供了一种新的技术手段。

In order to separate microparticles of different sizes,an inertial microfluidic chip with the micro⁃channel of triangular cross-section was proposed,and the characterization of particles focusing and separa⁃tion in the microchannel was studied.Firstly,a spiral channel with right-angled triangle cross-section was designed.Then,micro-milling was used to cut the microchannel in an aluminum mold,and casting and plasma cleaning were used to fabricate the microfluidic chip.Next,sample suspensions of three different fluorescent particles(6μm,10μm and 15μm)were prepared.The trajectories of particles in the channel were captured by a high-speed camera and a fluorescent microscope,and the focusing effect of particles un⁃der the different suspension flow rates was observed.Finally,the images of particle focusing were stacked and analyzed,and the inertial focusing and separation behavior of particles were studied.The results show that with the increase of the flow rate of particle suspension,the 6μm particles gradually focus and migrate towards the outer wall of the channel,while the focusing streams of 10μm and 15μm particles migrate to⁃wards the central channel.When the flow rate is set to 1.5 mL/min,the mixed suspension of 10μm and 15μm particles can be separated with the efficiency of 100%.This study demonstrates that the spiral mi⁃crochannel of triangular cross-section produces strongly skewed secondary flow,which can be applied for the high-efficiency and precise separation of microparticles of different sizes.The research findings will pro⁃vide new insights for accurate cell manipulation.