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|Title: ||Study In-Plane Elasticity of Alveolar Epithelial Cells with Different Oncogene Expression Levels using Microfluidic Device|
|Authors: ||Ko, P.-L.;Lee, T.-A.;Wang, C.-K.;Peng, C.-C.;Tung, Y.-C.|
|Keywords: ||Structural mechanics;Peak system response;Extreme load distribution;Optimal structural design|
|Issue Date: ||2017-05-18 02:10:38 (UTC+8)|
|Abstract: ||In this paper, we develop a microfluidic device with an embedded pressure sensor to study the in-plane direction elasticity of adenocarcinomic human alveolar epithelial (A549) cells with different oncogene, multiple copies in T-cell malignancy (MCT-1), expression levels . The pressure sensor is constructed based on electrofluidic circuits, ionic liquid-filled microfluidic channel networks, with great long-term and temperature stabilities. The device consists of three polydimethylsiloxane (PDMS) layers: a top cell culture chamber layer, a middle sensing membrane layer and a bottom electrofluidic circuit layer as shown in Figure 1(a). On the top layer, a cell culture chamber with a single inlet and a single outlet is designed to culture cells for the measurement. On the bottom ionic liquid-filled circuit layer, four identical electrofluidic resistors  designed and arranged as a Wheatstone bridge circuit as shown in Figure 1(b). The membrane is sandwiched between the top and bottom layers. When the membrane is deformed by pressure application, the geometries of the electofluidic channel will be changed, and the characteristic of the electrofluidic circuit will also be changed accordingly. The change will further vary the output voltage signal from the circuit. When cells are seeded on the top of the sensing membrane, the cell- adhered membrane can be modeled as a two-layer composite plate. To quantitatively estimate the in-plane elasticity of a layer of cells, we derive a theoretical model based on first order shear deformation theory of plate [3-4] and basic circuit theories to estimate the cell elasticity from the sensor sensitivity variation. For comparison, we use an atomic force microscope (AFM) to measure the out-of-plane elasticity and thickness of the A549 cells. The average measured thickness of A549 cells is 1.11μm. With the measured pressure sensor output signals and the sensing membrane geometries and mechanical properties, we can calculate the relationship between the Young’s modulus of the cells layer and the sensitivity ratio. The ratio is obtained from the same device with and without the cells cultured in it (Figure 2). In the experiments, A549-control cells (A549-C) and A549 cells with MCT-1 oncogene overexpression (A549-M)  are used to investigate their in-plane elasticities. Figure 3 shows bright field phase images of the A549 cells cultured in the microfluidic devices during the experiments. Figure 4 (a) and (b) show the typical average sensitivity of the pressure sensor devices cultured A549-C and A549-M cells, respectively. According to the Figure 2, we can estimate the in-plane elasticity of A549-C and A540-M cells layers. Figure 5 shows comparison of the average in-plane elasticities of the A549-C and A549-M cells measured using the developed microfluidic devices. The results show that the average in-plane elasticities of A549-C and A549-M are 3.91 MPa and 8.74 MPa (n=3), respectively. The results demonstrate that the developed device can successfully measure the in-plane elasticity of the cells, and the in-plane elasticity increases when MCT-1 oncogene overexpressed in the A549 cells. With the demonstrated capability, the developed device shows its great potential for study of cell physical properties with different gene expression profiles.|
|Relation: ||microTAS 2017|
|Appears in Collections:||[土木工程學系暨研究所] 會議論文|
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