Mikroakışkan çiplerde tek parçacık impedans ölçüm sistemi tasarımı

In recent years, cancer has become the number one killer in many countries and conventional diagnosis are very invasive, time-consuming, complicated process, and need stringent laboratory conditions. Traditional approaches study a group of cells which the results are averages and cannot exactly show individual cells. Hence single cell analyze is needed to associate cellular events with genomic information and plays an important role in biological measurement and medical research. The so-called "lab-on-a-chip" devices for handling samples in bio fluids are very applicable in biology and chemistry as they have lost of profits such as high resolution, very fast and inexpensive for analyzing and synthesizing and give the opportunity of manipulating of single cells, which is a key technology in cell engineering such as drug injection and gene introduction. For single cell analysis, cell impedance analysis has developed rapidly and has become an effective method of biological measurement. The temperature, electric conductivity and mobility of a cell can influence its impedance characteristics directly or indirectly so the cell impedance characteristic can be used to understand biological characteristic behavior. This Master's Thesis project presents a microfluidic chip for single-particle impedance measurement. The device with integrated actuation electrodes utilizes the DEP and controlled pressure-driven liquid flows to capture the single particle and sensing electrodes to measures the impedance of particle. The impedance was measured at different voltages ranges (0.1-2 V) between 3 KHz and 500 KHz. The impedance increase can be explained by a gradual blockage of the electrical path between the sensing electrodes. The impedance measurement over wide frequency range revealed that the impedance decreased as the frequency increased because of the double-layer capacitance on each electrode. In addition, the increment ratio was more evident for the particle experiment at the low frequency. Also it is obvious that with increasing the voltage, it was a slight decrease in impedance in most of frequencies. Furthermore comparison of the obtained results for DI water and 150mM NaCl shows less impedance magnitudes for 150mM NaCl which can be described due to increase of the conductivity of the suspending medium. The mean of impedance increased in DI water is 10.13% and in Nacl is 10.20%. Although different solutions are used for impedance evaluation of polystyrene particles, results in both case are close to each other with approximately 10% increasing.