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  • Küçük Resim Yok
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    Capacitive solvent sensing with interdigitated microelectrodes
    (Springer, 2016) Bilican, Ismail; Guler, Mustafa Tahsin; Gulener, Neset; Yuksel, Mustafa; Agan, Sedat
    We were able to quantify dielectric properties of solvents such as DI water, isopropyl alcohol, and acetone using interdigitated microelectrodes (IMEs). IMEs were fabricated using conventional micro fabrication techniques. The fabricated IMEs were dipped into the solution, and the dielectric property of the medium was measured. A range of frequencies and excitation voltages were swept in order to determine the operation region that yields the highest signal to noise ratio. Measurements were performed at 1 MHz and 100 mV which resulted in best signal to noise ratio. We applied a simple analytical model for the calculation of the capacitance and measured the capacitance value using a simple parallel capacitor and resistor model which resulted in perfect agreement with theoretical results. The presented sensor provides a simple and accurate method to determine solvent type which may have possible future applications.
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    Öğe
    Using nanogap in label-free impedance based electrical biosensors to overcome electrical double layer effect
    (Springer, 2017) Okyay, Ali Kemal; Hanoglu, Oguz; Yuksel, Mustafa; Acar, Handan; Sulek, Selim; Tekcan, Burak; Agan, Sedat
    Point-of-care biosensor applications require low-cost and low-power solutions. They offer being easily accessible at home site. They are usable without any complex sample handling or any kind of special expertise. Impedance spectroscopy has been utilized for point-of-care biosensor applications; however, electrical double layer formed due to ions in the solution of interest has been a challenge, due to shielding of the electric field used for sensing the target molecules. Here in this study, we demonstrate a nanogap based biosensor structure with a relatively low frequency (1-100 kHz) measurement technique, which not only eliminates the undesired shielding effect of electrical double layer but also helps in minimizing the measurement volume and enabling low concentration (A mu molar level) detection of target molecules (streptavidin). Repeatability and sensitivity tests proved stable and reliable operation of the sensors. These biosensors might offer attributes such as low-cost label-free detection, fast measurement and monolithic chip integrability.