Antfolk M, Muller P B, Augustsson P, Bruus H, Laurell T
Department of Biomedical Engineering, Lund University, Box 118, SE-221 00 Lund, Sweden.
Lab Chip. 2014 Aug 7;14(15):2791-9. doi: 10.1039/c4lc00202d. Epub 2014 Jun 4.
Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis-based microfluidic chip that uses ultrasound to focus sub-micrometer particles and bacteria, is presented. The ability to focus sub-micrometer bioparticles in a standing one-dimensional acoustic wave is generally limited by the acoustic-streaming-induced drag force, which becomes increasingly significant the smaller the particles are. By using two-dimensional acoustic focusing, i.e. focusing of the sub-micrometer particles both horizontally and vertically in the cross section of a microchannel, the acoustic streaming velocity field can be altered to allow focusing. Here, the focusability of E. coli and polystyrene particles as small as 0.5 μm in diameter in microchannels of square or rectangular cross sections, is demonstrated. Numerical analysis was used to determine generic transverse particle trajectories in the channels, which revealed spiral-shaped trajectories of the sub-micrometer particles towards the center of the microchannel; this was also confirmed by experimental observations. The ability to focus and enrich bacteria and other sub-micrometer bioparticles using acoustophoresis opens the research field to new microbiological applications.
在生物医学领域以及环境和食品分析中，处理诸如细菌等亚微米级生物颗粒变得越来越重要。因此，对劳动强度较低且耗时较少的处理方法的需求日益增加。在此，展示了一种基于声泳的微流控芯片，该芯片利用超声波聚焦亚微米级颗粒和细菌。在驻波一维声波中聚焦亚微米级生物颗粒的能力通常受到声流诱导的阻力限制，颗粒越小，这种阻力就越显著。通过使用二维声聚焦，即在微通道的横截面内水平和垂直地聚焦亚微米级颗粒，可以改变声流速度场以实现聚焦。在此，展示了在方形或矩形横截面的微通道中对直径小至0.5μm的大肠杆菌和聚苯乙烯颗粒的聚焦能力。数值分析用于确定通道中一般的横向颗粒轨迹，结果显示亚微米级颗粒朝着微通道中心呈螺旋形轨迹；实验观察也证实了这一点。利用声泳聚焦和富集细菌及其他亚微米级生物颗粒的能力为新的微生物学应用开辟了研究领域。
