Acoustic control of suspended particles in micro fluidic chips
Acoustic control of suspended particles in micro fluidic chips
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DOI：
10.1039/b313493h
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发表时间：
2004-01-01
期刊：
影响因子：
6.1
通讯作者：
Laurell, T
中科院分区：
文献类型：
--
作者：
Nilsson, A;Petersson, F;Laurell, T
描述了一种在微芯片水平上以连续模式从其介质中分离悬浮颗粒的方法。该方法将超声驻波场与硅微通道中获得的极端层流特性相结合。该通道为750 μ m宽和250 μ m深，具有通过各向异性湿法蚀刻限定的垂直侧壁。悬浮液包含“Orgasol 5 μ m”聚酰胺球和蒸馏水。通过向出口施加负压（抽吸）灌注通道。该通道由压电陶瓷板从芯片的背面超声致动。当在基本共振频率下操作声学分离器时，声学力不足以将颗粒聚焦到通道中心的良好限定的单个带中。因此，频率改变为约2 MHz，驻波中具有两个压力节点的第一谐波，因此形成两条颗粒线，其经由侧出口收集。研究了两种不同的微芯片分离器设计，其中出口通道分别以90度和45度的角度从分离通道分叉。45 °分离器表现出最佳的流体动力学性能，90%的颗粒聚集在原始流体体积的2/3中。
A method to separate suspended particles from their medium in a continuous mode at microchip level is described. The method combines an ultrasonic standing wave field with the extreme laminar flow properties obtained in a silicon micro channel. The channel was 750 mum wide and 250 mum deep with vertical side walls defined by anisotropic wet etching. The suspension comprised "Orgasol 5mum" polyamide spheres and distilled water. The channel was perfused by applying an under pressure ( suction) to the outlets. The channel was ultrasonically actuated from the back side of the chip by a piezoceramic plate. When operating the acoustic separator at the fundamental resonance frequency the acoustic forces were not strong enough to focus the particles into a well defined single band in the centre of the channel. The frequency was therefore changed to about 2 MHz, the first harmonic with two pressure nodes in the standing wave, and consequently two lines of particles were formed which were collected via the side outlets. Two different microchip separator designs were investigated with exit channels branching off from the separation channel at angles of 90degrees and 45degrees respectively. The 45degrees separator displayed the most optimal fluid dynamic properties and 90% of the particles were gathered in 2/3 of the original fluid volume.