Neild Adrian, Oberti Stefano, Haake Albrecht, Dual Jürg
Center of Mechanics, ETH Zurich, 8092 Zurich, Switzerland.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e455-60. doi: 10.1016/j.ultras.2006.05.168. Epub 2006 Jun 9.
The contactless movement of microparticles and cells to known locations within a fluid volume is of interest in the fields of microtechnology and life sciences. A device which can position such inhomogeneities suspended in a fluid at multiple locations is described and modeled. The device consists of a thin fluid layer contained in a channel etched into a silicon wafer. Waves are excited by a macro-piezoelectric plate with electrodes on the top and bottom surfaces and, as a result, waves propagate into the adjacent fluid. The result is a pressure field throughout the fluidic volume. When an inhomogeneity in a fluid is exposed to an ultrasonic field the acoustic radiation force results; this is found by integrating the pressure over the surface of the particle, retaining second order terms, and taking the time average. Thus, due to the presence of a pressure field in the fluid in which the particles are suspended, a force field is created. The particles are then collected at the locations of the force potential minima. In the device described here, the force field is used to position particles into lines. The locations of the particles are predicted by using a finite element model of the system. The experimental and modeling results, presented here, are in good agreement.
微粒和细胞在流体体积内非接触地移动到已知位置，这在微技术和生命科学领域备受关注。本文描述并建模了一种能够将悬浮在流体中的此类不均匀性物质定位在多个位置的装置。该装置由包含在蚀刻于硅片上的通道中的薄流体层组成。通过在上下表面带有电极的宏观压电板激发波，结果波传播到相邻流体中。其结果是在整个流体体积内形成一个压力场。当流体中的不均匀性物质暴露于超声场时会产生声辐射力；这是通过在粒子表面对压力进行积分、保留二阶项并取时间平均值得到的。因此，由于粒子悬浮其中的流体中存在压力场，从而创建了一个力场。然后粒子在力势极小值的位置被收集。在此描述的装置中，力场用于将粒子排列成线。通过使用该系统的有限元模型预测粒子的位置。本文给出的实验和建模结果吻合良好。
