| dc.description.abstract | Impedance spectroscopy based microfluidics have the capability to characterize the dielectric properties of mediums, particles, cellular and sub-cellular contents in response to stimulating voltage signals over a frequency range. This label-free technology has broad ranges of applications in life sciences where there is a need for high-throughput, label-free, non-contact, and low-cost microsystems. To address these limitations, three innovative impedance spectroscopy microfluidic platforms have been developed and presented in this dissertation. The first platform was developed for detecting and characterizing the transverse position of a single cell flowing within a microfluidic channel using a single impedance spectroscopy electrode pair. Regardless of the cell separation methods used, identifying and quantifying the position of cells and particles within a microchannel are important, as these information indicate both the degree of separation as well as how many cells are separated into each position. Using a single pair of non-parallel surface microelectrodes, five different transverse positions of single cells flowing through a microfluidic channel were successfully identified at a throughput of more than 400 particles/s using the detected impedance peak height and width.
The second platform utilizes the above technology to count and quantify cells flowing through multiple outlets of microfluidic cell separation systems. A single pair of step-shaped electrodes was developed by integrating five different electrode-to-electrode gaps within a single pair of electrodes. Using this platform, an overall misclassification error rate of only 1.85% was achieved. The result shows the technology’s capability in
achieving efficient on-chip cell counting and quantification, regardless of the cell separation methods used, making it a promising on-chip, low-cost and label-free quantification method for cell and particle sorting and separation applications.
The third platform was developed for counting cells and particles encapsulated in water-in-oil emulsion droplets using microfluidic based impedance spectroscopy systems. Impedance signal peak height and width were utilized to successfully quantify the number of cells encapsulated within a droplet, and was successfully applied for various cell types and growth media. In addition, the developed platform has been also successfully tested for identifying and discriminating filamentous fungal cell growth, where single fungal spores and filamentous fungi of different lengths could be discriminated inside droplets.
Overall in this research, several impedance spectroscopy based microfluidic systems have been successfully developed to solve current limitations in technologies that need high-throughput, low-cost and label-free detection and characterization method for a broad range of cell/particle screening applications. | en |
