A microfluidic device for impedance spectroscopy analysis of biological samples
A microfluidic device for impedance spectroscopy analysis of biological samples
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DOI：
10.1016/j.snb.2006.08.009
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发表时间：
2007-04-10
影响因子：
8.4
通讯作者：
Loe, Felicia C.
中科院分区：
文献类型：
--
作者：
Iliescu, Ciprian;Poenar, Daniel P.;Loe, Felicia C.
本文提出了一个原始的微流控装置的制造过程中的识别和表征的细胞悬浮液中使用阻抗谱。该装置由两个玻璃晶片组成：底部晶片包括微流体通道，其中添加了两个电极用于阻抗测量，以及顶部玻璃晶片，其中实现了入口和出口。该装置是基于玻璃的，这一事实提供了一些关键的优点：在测量过程中减少寄生成分的影响（由于基板的良好隔离特性），光学透明度和微流体通道的亲水表面。后一个特征是特别重要的，因为其仅由于毛细作用力而使得样品抽吸成为可能。因此，不需要外部泵送，并且仅小体积的样品就足以进行测量。该器件的制造过程包括三个主要步骤。首先，通过在49%HF溶液中使用低应力非晶硅/碳化硅/光致抗蚀剂掩模进行湿法蚀刻，在顶部玻璃晶片中形成通孔和入口/出口孔。其次，微流体通道被蚀刻到底部晶片中，然后使用基于喷涂的光刻在其顶部图案化Ti/Pt电极。最后的处理步骤是通过使用非常薄的粘合剂中间层（SU 8）将顶部和底部玻璃晶片结合在一起。该粘合剂层使用接触压印方法从特氟隆圆柱体选择性地仅施加在底部模具上。最后，使用去离子水、磷酸盐缓冲盐水（PBS）以及重悬于PBS中的死酵母细胞和活酵母细胞成功地测试了具有三种不同电极几何形状的装置。已经观察到死细胞和活细胞之间的明显差异。(c)2006 Elsevier B. V.保留所有权利。
The paper presents an original fabrication process of a microfluidic device for identification and characterization of cells in suspensions using impedance spectroscopy. The device consists of two glass wafers: a bottom wafer comprising a microfluidic channel with two electrodes added for impedance measurement, and a top glass wafer in which inlets and outlets are realized. The fact that the device is glass-based provides a few key advantages: reduced influence from parasitic components during measurements (due to the good isolation properties of the substrate), optical transparency and hydrophilic surface of the microfluidic channel. The latter feature is especially important as it enables sample suction due to capillarity forces only. Thus, no external pumping is required and only a small volume sample suffices for the measurement. The fabrication process of this device consists of three major steps. First, via-holes and inlet/outlet holes are executed in the top glass wafer by wet etching in a 49% HF solution using a low stress amorphous silicon/silicon carbide/photoresist mask. Second, the microfluidic channel is etched into the bottom wafer and Ti/Pt electrodes are then patterned on top of it using a spray coating-based lithography. The last processing step is bonding together the top and bottom glass wafers by employing a very thin adhesive intermediate layer (SU8). This adhesive layer was applied selectively only on the bottom die, from a Teflon cylinder, using a contact imprinting method. Finally, devices with three different electrode geometries were successfully tested using DI water, phosphate buffer saline (PBS), and both dead and living yeast cells resuspended in PBS. Clear differences between dead and live cells have been observed. (c) 2006 Elsevier B.V. All rights reserved.