Çok modlu mikrodalga sensörleri ile mikrodamlacık ve tek hücre saptanması

A novel detection mechanism which can reveal both morphological and electrical properties of analytes are needed for Lab-on-a-Chip applications. Herein, a label-free, real-time and non-contact detection paradigm in microwave domain is constructed, by using first and second electromagnetic modes of a microwave resonator. As the resonator, microstrip line is chosen since it offers accessible boundary conditions. In order to deliver the analytes into the sensing region, microfluidic channels are fabricated. As a proof-of-concept, while the microstrip line resonator's first and second modes are tracked simultaneously, analytes are delivered through the microchannel embedded underneath the signal layer. As the analytes, water microdroplets in oil, cervical (HeLa) and breast (MDA-MB-157) cancer cells in their appropriate medium are used and detected; their position and electrical volume informations are obtained and compared. Allan Deviation of the measurement is smaller than $2\times 10^{-8}$ for both modes, and due to analyte properties in microwave domain, such as the great permittivity difference between the biological analyte and medium, detection is possible. In order to test the accuracy of finding the position of the analyte, two different microchannel geometries are designed. The first geometry is based on a zigzag channel, where microstrip line crosses the channel at 6 different locations. Secondly, a branched channel is designed, to send the microdroplets at four different locations. This delivery mechanism is mostly based on the hydraulic resistance: Each droplet chooses its path by the hydraulic resistance that is caused by the previous droplet. Hence, microdroplets are distributed to four channels. Due to the mode shape of the specific mode, when analyte passing through these regions, it induces different frequency shifts. For these applications, microfluidic part is fabricated by conventional soft lithography methods, and the material for the microchannels is PDMS. Electrical volume of the droplets is also obtained. After the usage of prototypes for position and electrical volume calculations, second generation devices are fabricated. Compared to the PDMS-based devices, these devices offer rapid and low-cost prototyping. Additionally, Kapton is chosen for the dielectric material, and it has some material-wise benefits, such as the tangent loss level. Analytes are delivered through the sensing region by capillary tubings, hence soft lithography steps can be eliminated. Due to the equipment limitations, only the first mode is tracked with these novel devices, while another type of breast cancer cells (SK-BR-3) are delivered through the sensing region. Signal-to-noise ratio, when compared to the PDMS based devices, is improved. In this work, the first two modes of microstrip line resonators are used. However, by using higher order modes, more properties about the particles as skewness, geometrical volume, orientation, and composition can be obtained. These informations can be used to construct a global image of the analyte; rather than a pixel by pixel image. Additionally, flow cytometry applications, detection of Circulating Tumour Cells and applications for long term cultivation on chip (also known as Organ-on-Chip platforms) can be achieved.