@article{PourshahidiEngelmannOffenhaeusseretal.2022,
  author    = {Pourshahidi, Ali Mohammad and Engelmann, Ulrich M. and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim},
  title     = {Resolving ambiguities in core size determination of magnetic nanoparticles from magnetic frequency mixing data},
  series = {Journal of Magnetism and Magnetic Materials},
  volume    = {563},
  journal   = {Journal of Magnetism and Magnetic Materials},
  number    = {In progress, Art. No. 169969},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0304-8853},
  doi       = {10.1016/j.jmmm.2022.169969},
  year      = {2022},
  abstract  = {Frequency mixing magnetic detection (FMMD) has been widely utilized as a measurement technique in magnetic immunoassays. It can also be used for the characterization and distinction (also known as "colourization") of different types of magnetic nanoparticles (MNPs) based on their core sizes. In a previous work, it was shown that the large particles contribute most of the FMMD signal. This leads to ambiguities in core size determination from fitting since the contribution of the small-sized particles is almost undetectable among the strong responses from the large ones. In this work, we report on how this ambiguity can be overcome by modelling the signal intensity using the Langevin model in thermodynamic equilibrium including a lognormal core size distribution fL(dc,d0,σ) fitted to experimentally measured FMMD data of immobilized MNPs. For each given median diameter d0, an ambiguous amount of best-fitting pairs of parameters distribution width σ and number of particles Np with R2 > 0.99 are extracted. By determining the samples' total iron mass, mFe, with inductively coupled plasma optical emission spectrometry (ICP-OES), we are then able to identify the one specific best-fitting pair (σ, Np) one uniquely. With this additional externally measured parameter, we resolved the ambiguity in core size distribution and determined the parameters (d0, σ, Np) directly from FMMD measurements, allowing precise MNPs sample characterization.},
  language  = {en}
}
@article{PourshahidiAchtsnichtOffenhaeusseretal.2022,
  author    = {Pourshahidi, Ali Mohammad and Achtsnicht, Stefan and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim},
  title     = {Frequency Mixing Magnetic Detection Setup Employing Permanent Ring Magnets as a Static Offset Field Source},
  series = {Sensors},
  volume    = {22},
  journal   = {Sensors},
  number    = {22},
  editor    = {Offenh{\"a}usser, Andreas},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s22228776},
  pages     = {12 Seiten},
  year      = {2022},
  abstract  = {Frequency mixing magnetic detection (FMMD) has been explored for its applications in fields of magnetic biosensing, multiplex detection of magnetic nanoparticles (MNP) and the determination of core size distribution of MNP samples. Such applications rely on the application of a static offset magnetic field, which is generated traditionally with an electromagnet. Such a setup requires a current source, as well as passive or active cooling strategies, which directly sets a limitation based on the portability aspect that is desired for point of care (POC) monitoring applications. In this work, a measurement head is introduced that involves the utilization of two ring-shaped permanent magnets to generate a static offset magnetic field. A steel cylinder in the ring bores homogenizes the field. By variation of the distance between the ring magnets and of the thickness of the steel cylinder, the magnitude of the magnetic field at the sample position can be adjusted. Furthermore, the measurement setup is compared to the electromagnet offset module based on measured signals and temperature behavior.},
  language  = {en}
}
@article{PourshahidiAchtsnichtNambipareecheeetal.2021,
  author    = {Pourshahidi, Ali Mohammad and Achtsnicht, Stefan and Nambipareechee, Mrinal Murali and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim},
  title     = {Multiplex detection of magnetic beads using offset field dependent frequency mixing magnetic detection},
  series = {Sensors},
  volume    = {21},
  journal   = {Sensors},
  number    = {17},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s21175859},
  pages     = {16 Seiten},
  year      = {2021},
  abstract  = {Magnetic immunoassays employing Frequency Mixing Magnetic Detection (FMMD) have recently become increasingly popular for quantitative detection of various analytes. Simultaneous analysis of a sample for two or more targets is desirable in order to reduce the sample amount, save consumables, and save time. We show that different types of magnetic beads can be distinguished according to their frequency mixing response to a two-frequency magnetic excitation at different static magnetic offset fields. We recorded the offset field dependent FMMD response of two different particle types at frequencies ƒ₁ + n⋅ƒ₂, n = 1, 2, 3, 4 with ƒ₁ = 30.8 kHz and ƒ₂ = 63 Hz. Their signals were clearly distinguishable by the locations of the extremes and zeros of their responses. Binary mixtures of the two particle types were prepared with different mixing ratios. The mixture samples were analyzed by determining the best linear combination of the two pure constituents that best resembled the measured signals of the mixtures. Using a quadratic programming algorithm, the mixing ratios could be determined with an accuracy of greater than 14\%. If each particle type is functionalized with a different antibody, multiplex detection of two different analytes becomes feasible.},
  language  = {en}
}
@article{PolenKraemerBongaertsetal.2005,
  author    = {Polen, T. and Kr{\"a}mer, Marco and Bongaerts, Johannes and Wubbolts, Marcel and Wendisch, V. F.},
  title     = {The global gene expression response of Escherichia coli to L-phenylalanine},
  series = {Journal of biotechnology},
  volume    = {Vol. 115},
  journal   = {Journal of biotechnology},
  number    = {Iss. 3},
  issn      = {1873-4863 (E-Journal); 0168-1656 (Print)},
  pages     = {221 -- 237},
  year      = {2005},
  language  = {en}
}
@article{PoghossianYoshinobuSimonisetal.2001,
  author    = {Poghossian, Arshak and Yoshinobu, Tatsuo and Simonis, A. and Ecken, H. and L{\"u}th, Hans and Sch{\"o}ning, Michael Josef},
  title     = {Penicillin detection by means of field-effect based sensors: EnFET, capacitive EIS sensor or LAPS?},
  series = {Sensors and Actuators B. 78 (2001), H. 1-3},
  journal   = {Sensors and Actuators B. 78 (2001), H. 1-3},
  isbn      = {0925-4005},
  pages     = {237 -- 242},
  year      = {2001},
  language  = {en}
}
@article{PoghossianYoshinobuSchoening2003,
  author    = {Poghossian, Arshak and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {Flow-velocity microsensors based on semiconductor field-effect structures},
  series = {Sensors. 3 (2003), H. 7},
  journal   = {Sensors. 3 (2003), H. 7},
  isbn      = {1424-8220},
  pages     = {202 -- 212},
  year      = {2003},
  language  = {en}
}
@article{PoghossianYoshinobuSimonisetal.2000,
  author    = {Poghossian, Arshak and Yoshinobu, T. and Simonis, A. and Ecken, H. and L{\"u}th, H. and Sch{\"o}ning, Michael Josef},
  title     = {Penicillin detection by means of field-effect based sensors: EnFET, capacitive EIS sensor or LAPS?},
  series = {Proceedings : Copenhagen, Denmark, 27 - 30 August 2000 / [ed.: R. de Reus ...]},
  journal   = {Proceedings : Copenhagen, Denmark, 27 - 30 August 2000 / [ed.: R. de Reus ...]},
  publisher = {MIC, Mikroelektronik Centret},
  address   = {Lyngby, Denmark},
  isbn      = {87-89935-50-0},
  pages     = {27 -- 30},
  year      = {2000},
  language  = {en}
}
@article{PoghossianWernerBuniatyanetal.2017,
  author    = {Poghossian, Arshak and Werner, Frederik and Buniatyan, V. V. and Wagner, Torsten and Miamoto, K. and Yoshinobu, T. and Sch{\"o}ning, Michael Josef},
  title     = {Towards addressability of light-addressable potentiometric sensors: Shunting effect of non-illuminated region and cross-talk},
  series = {Sensor and Actuators B: Chemical},
  journal   = {Sensor and Actuators B: Chemical},
  number    = {244},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2017.01.047},
  pages     = {1071 -- 1079},
  year      = {2017},
  abstract  = {The LAPS (light-addressable potentiometric sensor) platform is one of the most attractive approaches for chemical and biological sensing with many applications ranging from pH and ion/analyte concentration measurements up to cell metabolism detection and chemical imaging. However, although it is generally accepted that LAPS measurements are spatially resolved, the light-addressability feature of LAPS devices has not been discussed in detail so far. In this work, an extended electrical equivalent-circuit model of the LAPS has been presented, which takes into account possible cross-talk effects due to the capacitive coupling of the non-illuminated region. A shunting effect of the non-illuminated area on the measured photocurrent and addressability of LAPS devices has been studied. It has been shown, that the measured photocurrent will be determined not only by the local interfacial potential in the illuminated region but also by possible interfacial potential changes in the non-illuminated region, yielding cross-talk effects. These findings were supported by the experimental investigations of a penicillin-sensitive multi-spot LAPS and a metal-insulator-semiconductor LAPS as model systems.},
  language  = {en}
}
@article{PoghossianWeldenBuniatyanetal.2021,
  author    = {Poghossian, Arshak and Welden, Rene and Buniatyan, Vahe V. and Sch{\"o}ning, Michael Josef},
  title     = {An Array of On-Chip Integrated, Individually Addressable Capacitive Field-Effect Sensors with Control Gate: Design and Modelling},
  series = {Sensors},
  volume    = {21},
  journal   = {Sensors},
  number    = {18},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s21186161},
  pages     = {17},
  year      = {2021},
  abstract  = {The on-chip integration of multiple biochemical sensors based on field-effect electrolyte-insulator-semiconductor capacitors (EISCAP) is challenging due to technological difficulties in realization of electrically isolated EISCAPs on the same Si chip. In this work, we present a new simple design for an array of on-chip integrated, individually electrically addressable EISCAPs with an additional control gate (CG-EISCAP). The existence of the CG enables an addressable activation or deactivation of on-chip integrated individual CG-EISCAPs by simple electrical switching the CG of each sensor in various setups, and makes the new design capable for multianalyte detection without cross-talk effects between the sensors in the array. The new designed CG-EISCAP chip was modelled in so-called floating/short-circuited and floating/capacitively-coupled setups, and the corresponding electrical equivalent circuits were developed. In addition, the capacitance-voltage curves of the CG-EISCAP chip in different setups were simulated and compared with that of a single EISCAP sensor. Moreover, the sensitivity of the CG-EISCAP chip to surface potential changes induced by biochemical reactions was simulated and an impact of different parameters, such as gate voltage, insulator thickness and doping concentration in Si, on the sensitivity has been discussed.},
  language  = {en}
}
@incollection{PoghossianWeilandSchoening2014,
  author    = {Poghossian, Arshak and Weiland, Maryam and Sch{\"o}ning, Michael Josef},
  title     = {Nanoplate field-effect capacitors: a new transducer structure for multiparameter (bio-)chemical sensing},
  series = {Multisensor system for chemical analysis : materials and sensors},
  booktitle = {Multisensor system for chemical analysis : materials and sensors},
  editor    = {Lvova, Larisa and Kirsanov, Dmitry and di Natale, Corrado and Legin, Audrey},
  edition   = {1},
  publisher = {Jenny Stanford Publishing},
  address   = {Singapore},
  isbn      = {978-981-4411-15-8 ; 978-981-4411-16-5},
  doi       = {10.1201/b15491-11},
  pages     = {333 -- 373},
  year      = {2014},
  abstract  = {An array of electrically isolated nanoplate field-effect silicon-on-insulator (SOI) capacitors as a new transducer structure for multiparameter (bio-)chemical sensing is presented. The proposed approach allows addressable biasing and electrical readout of multiple nanoplate field-effect capacitive (bio-)chemical sensors on the same SOI chip, as well as differential-mode measurements. The realized sensor chip has been applied for pH and penicillin concentration measurements, electrical monitoring of polyelectrolyte multilayer formation, and the label-free electrical detection of consecutive deoxyribonucleic acid (DNA) hybridization and denaturation events.},
  language  = {en}
}