- 學位論文
應用微流道嵌入壓力感測器於細胞硬度量測裝置開發
Development of Cell Rigidity Detection Device based on embedded Electrofluidic Pressure Sensor
摘要
細胞是生物最基本的組成，因而細胞研究在生物學上是非常重要的課題，而了解在細胞周圍微小環境也很重要，因為細胞會對於周圍環境的改變作出感知和反應，因此微小環境對於細胞的機能和行為有很大的影響。探討細胞的機械性質則有助我們了解細胞對於外在環境會產生如何的反應，其中，細胞的彈性(或硬度)可能是最重要的機械性質之一，這是由於細胞的功能與其結構組織息息相關，而彈性又決定了結構組織的特性，過去有許多學者利用細胞的軟硬程度應用在相關研究上，例如以細胞的硬度去區分癌細胞與正常細胞，或是利用細胞的硬度差異對不同細胞群快速的分類。過去的十年間，最常用來決定細胞硬度的方法是透過原子力顯微鏡：將原子力施加在細胞上並偵測其形變量進而推得細胞的楊氏係數。但是依照原子力顯微鏡的原理，細胞被探討的是垂直細胞貼附平面方向上的硬度。而細胞被認為是非等向性的物質，沿著貼附平面方向上的硬度可能比垂直方向上的硬度還重要，因為細胞在生物活動中較常經歷的是平面方向上的延展。本研究開發了一包含電流道型壓力感測器的微流道裝置，用於探討細胞在平面方向上的硬度。此壓力感測器是基於以離子液體在微流道中建立的惠斯同電橋，利用施加的壓力改變裝置的幾何形狀，反映在電路上進而轉換成電壓訊號輸出。而根據此方法，一旦將細胞植入在裝置中改變其機械性質，細胞的硬度可以從植入前後電壓訊號上的差異推算而得。由於裝置中的幾何形變是基於樑理論，本裝置可以量測到是群體細胞在平面方向上的硬度。而所探討在平面方向上的延展與肺部的活動狀況類似，所以本實驗採用植入裝置的是人類肺部纖維母細胞。實驗結果顯示細胞的楊氏係數範圍介於547kPa到412kPa，此結果比起以往用原子力顯微鏡所量測的硬度有顯著差異，這說明了細胞的非等向性而可以從細胞的結構上做出解釋：細胞在平面方向上用於支撐的骨架與細胞自身相比，擁有相當強大的機械強度，而造成硬度的非等向性。本研究所開發之裝置具有許多優點，例如長期的監控細胞硬度將會對未來研究上有許多其他的應用。
並列摘要
Cells research is one of the most important studies in biology since cells are the basic unit of life. Understanding the cell microenvironments (including biochemical, physical and physicochemical factors) is also important because cells sense and respond the changes in their environments and thus the microenvironments have great influence on the function and behavior of cells. Therefore, investigation on the mechanical properties of cells is essential because it is one of the connections between cells and the microenvironments. Among various mechanical properties, the elasticity (or rigidity) is probably the most important because the cells functions are determined by their structures which are characterized by their elasticity. Previous studied has shown the application of investigation on cell rigidity such as cancerous cell distinction and cell sorting. Over the past decade, the most common way to determine the cell rigidity is the atomic force microscopy (AFM). By applying force on the cells and detect the deformation causing from the force, the Young’s modulus of the cells can be determined. However, according to its working principle, the AFM is mainly concerned with the rigidity in the direction normal to substrate where the cells attached. Cells are considered to be anisotropic and the rigidity in along the substrate direction is more important because cells commonly experience stretch in this direction. This thesis develops a microfluidic device with embedded electrofluidic circuit pressure sensor to investigate the in-plane cell rigidity. The method of the pressure sensor is constructed by an ionic-liquid based Wheatstone bridge circuit. The applying pressure alters the geometries of the microfluidic channel in the device and further changes the characteristics of the circuit and consequently can be read out by voltage signal. Based on this method, once the cells are seeded into the device, the mechanical propertied of the device will be changed and thus by comparing the voltage readout before and after cell seeding, the mechanical properties of the cells can be acquired. Since the deformation mechanism is based on the beam theory, the in-plane, group cell rigidity is investigated by the device. The human embryonal lung fibroblast cells (MRC-5) is used in this thesis because the in-plane stretch in the device has the similar mechanical condition in human lung. The experiment result shows that the in-plane rigidity of MRC-5s ranges from 547kPa to 412kPa which is much larger than the value measured by previous study. The result demonstrates the anisotropism of cell mechanical properties and can be explained by the in-plane structure of cells. In the plane direction, cells are connected by cytoskeleton which also has much larger Young’s modulus of several Giga-Pascale. Consequently, the device shows various advantages such as long-term monitoring and thus can help to develop the application for the future research.