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- ItemTowards Bacteria Counting in DI Water of Several Microliters or Growing Suspension Using Impedance Biochips(Basel : MDPI, 2020) Kiani, Mahdi; Tannert, Astrid; Du, Nan; Hübner, Uwe; Skorupa, Ilona; Bürger, Danilo; Zhao, Xianyue; Blaschke, Daniel; Rebohle, Lars; Cherkouk, Charaf; Neugebauer, Ute; Schmidt, Oliver G.; Schmidt, HeidemarieWe counted bacterial cells of E. coli strain K12 in several-microliter DI water or in several-microliter PBS in the low optical density (OD) range (OD = 0.05–1.08) in contact with the surface of Si-based impedance biochips with ring electrodes by impedance measurements. The multiparameter fit of the impedance data allowed calibration of the impedance data with the concentration cb of the E. coli cells in the range of cb = 0.06 to 1.26 × 109 cells/mL. The results showed that for E. coli in DI water and in PBS, the modelled impedance parameters depend linearly on the concentration of cells in the range of cb = 0.06 to 1.26 × 109 cells/mL, whereas the OD, which was independently measured with a spectrophotometer, was only linearly dependent on the concentration of the E. coli cells in the range of cb = 0.06 to 0.50 × 109 cells/mL.
- ItemP-N junction-based Si biochips with ring electrodes for novel biosensing applications(Basel : MDPI, 2019) Kiani, Mahdi; Du, Nan; Vogel, Manja; Raff, Johannes; Hübner, Uwe; Skorupa, Ilona; Bürger, Danilo; Schulz, Stefan E.; Schmidt, Oliver G.; Schmidt, HeidemarieIn this work, we report on the impedance of p-n junction-based Si biochips with gold ring top electrodes and unstructured platinum bottom electrodes which allows for counting target biomaterial in a liquid-filled ring top electrode region. The systematic experiments on p-n junction-based Si biochips fabricated by two different sets of implantation parameters (i.e. biochips PS5 and BS5) are studied, and the comparable significant change of impedance characteristics in the biochips in dependence on the number of bacteria suspension, i.e., Lysinibacillus sphaericus JG-A12, in Deionized water with an optical density at 600 nm from OD600 = 4–16 in the electrode ring region is demonstrated. Furthermore, with the help of the newly developed two-phase electrode structure, the modeled capacitance and resistance parameters of the electrical equivalent circuit describing the p-n junction-based biochips depend linearly on the number of bacteria in the ring top electrode region, which successfully proves the potential performance of p-n junction-based Si biochips in observing the bacterial suspension. The proposed p-n junction-based biochips reveal perspective applications in medicine and biology for diagnosis, monitoring, management, and treatment of diseases.In this work, we report on the impedance of p-n junction-based Si biochips with gold ring top electrodes and unstructured platinum bottom electrodes which allows for counting target biomaterial in a liquid-filled ring top electrode region. The systematic experiments on p-n junction-based Si biochips fabricated by two different sets of implantation parameters (i.e. biochips PS5 and BS5) are studied, and the comparable significant change of impedance characteristics in the biochips in dependence on the number of bacteria suspension, i.e., Lysinibacillus sphaericus JG-A12, in Deionized water with an optical density at 600 nm from OD600 = 4–16 in the electrode ring region is demonstrated. Furthermore, with the help of the newly developed two-phase electrode structure, the modeled capacitance and resistance parameters of the electrical equivalent circuit describing the p-n junction-based biochips depend linearly on the number of bacteria in the ring top electrode region, which successfully proves the potential performance of p-n junction-based Si biochips in observing the bacterial suspension. The proposed p-n junction-based biochips reveal perspective applications in medicine and biology for diagnosis, monitoring, management, and treatment of diseases.
- ItemMagnetooptical response of permalloy multilayer structures on different substrate in the IR-VIS-UV spectral range(Bristol : IOP Publ., 2019) Patra, Rajkumar; Mattheis, Roland; Stöcker, Hartmut; Monecke, Manuel; Salvan, Georgeta; Schäfer, Rudolf; Schmidt, Oliver G.; Schmidt, HeidemarieThe magnetooptical (MO) response of Ru/Py/Ta thin film stacks with 4, 8, and 17 nm thick Ni81Fe19 permalloy (Py) films on a SiO2/Si and a ZnO substrate was measured by vector magnetooptical generalized ellipsometry. The MO response from VMOGE was modelled using a 4 × 4 Mueller matrix algorithm. The wavelength-dependent, substrate-independent and thickness-independent complex MO coupling constant (Q) of Py in the Ru/Py/Ta thin film stacks was extracted by fitting Mueller matrix difference spectra in the spectral range from 300 nm to 1000 nm. Although the composition-dependent saturation magnetization of NixFe1−x alloys (x = 0.0...1.0), e.g. of Ni81Fe19, is predictable from the two saturation magnetization end points, the MO coupling constant of NixFe1−x is not predictable from the two Q end points. However, in a small alloy range (0.0 < x < 0.2 and 0.8 < x < 1.0) the composition-dependent Q of NixFe1−x can be interpolated from a sufficiently high number of analyzed NixFe1−x alloys. The available complex MO coupling constants of six different NixFe1−x (x = 1.0 to 0.0) alloys were used to interpolate MO response of binary NixFe1−x alloys in the range from x = 0.0 to x = 1.0.