TY  - JOUR
A1  - Werner, Frederik
A1  - Wagner, Torsten
A1  - Yoshinobu, Tatsuo
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Frequency behaviour of light-addressable potentiometric sensors
JF  - Physica Status Solidi (A)
N2  - Light-addressable potentiometric sensors (LAPS) are semiconductor-based potentiometric sensors, with the advantage to detect the concentration of a chemical species in a liquid solution above the sensor surface in a spatially resolved manner. The addressing is achieved by a modulated and focused light source illuminating the semiconductor and generating a concentration-depending photocurrent. This work introduces a LAPS set-up that is able to monitor the electrical impedance in addition to the photocurrent. The impedance spectra of a LAPS structure, with and without illumination, as well as the frequency behaviour of the LAPS measurement are investigated. The measurements are supported by electrical equivalent circuits to explain the impedance and the LAPS-frequency behaviour. The work investigates the influence of different parameters on the frequency behaviour of the LAPS. Furthermore, the phase shift of the photocurrent, the influence of the surface potential as well as the changes of the sensor impedance will be discussed.
Y1  - 2013
U6  - https://doi.org/10.1002/pssa.201200929
SN  - 1521-396X ; 0031-8965
VL  - 210
IS  - 5
SP  - 884
EP  - 891
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Huck, Christina
A1  - Schiffels, Johannes
A1  - Herrera, Cony N.
A1  - Schelden, Maximilian
A1  - Selmer, Thorsten
A1  - Poghossian, Arshak
A1  - Baumann, Marcus
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - Metabolic responses of Escherichia coli upon glucose pulses captured by a capacitive field-effect sensor
JF  - Physica Status Solidi (A)
N2  - Living cells are complex biological systems transforming metabolites taken up from the surrounding medium. Monitoring the responses of such cells to certain substrate concentrations is a challenging task and offers possibilities to gain insight into the vitality of a community influenced by the growth environment. Cell-based sensors represent a promising platform for monitoring the metabolic activity and thus, the “welfare” of relevant organisms. In the present study, metabolic responses of the model bacterium Escherichia coli in suspension, layered onto a capacitive field-effect structure, were examined to pulses of glucose in the concentration range between 0.05 and 2 mM. It was found that acidification of the surrounding medium takes place immediately after glucose addition and follows Michaelis–Menten kinetic behavior as a function of the glucose concentration. In future, the presented setup can, therefore, be used to study substrate specificities on the enzymatic level and may as well be used to perform investigations of more complex metabolic responses. Conclusions and perspectives highlighting this system are discussed.
Y1  - 2013
U6  - https://doi.org/10.1002/pssa.201200900
SN  - 0031-8965
VL  - 210
IS  - 5
SP  - 926
EP  - 931
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Bäcker, Matthias
A1  - Schusser, Sebastian
A1  - Poghossian, Arshak
A1  - Schöning, Michael Josef
T1  - Degradationsverhalten bioabbaubarer Polymere : siliziumbasierte Sensorik zur Überwachung
JF  - GIT Labor-Fachzeitschrift
Y1  - 2013
SN  - 0016-3538
SP  - 32
EP  - 33
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Gräßl, Andreas
A1  - Renz, Wolfgang
A1  - Hezel, Fabian
A1  - Dieringer, Matthias A.
A1  - Winter, Lukas
A1  - Özerdem, Celal
A1  - Rieger, Jan
A1  - Kellmann, Peter
A1  - Santoro, Davide
A1  - Lindel, Tomasz D.
A1  - Frauenrath, Tobias
A1  - Pfeiffer, Harald
A1  - Niendorf, Thoralf
T1  - Modular 32-channel transceiver coil array for cardiac MRI at 7.0T
JF  - Magnetic Resonance in Medicine
N2  - Purpose
To design and evaluate a modular transceiver coil array with 32 independent channels for cardiac MRI at 7.0T.

Methods
The modular coil array comprises eight independent building blocks, each containing four transceiver loop elements. Numerical simulations were used for B1+ field homogenization and radiofrequency (RF) safety validation. RF characteristics were examined in a phantom study. The array's suitability for accelerated high spatial resolution two-dimensional (2D) FLASH CINE imaging of the heart was examined in a volunteer study.

Results
Transmission field adjustments and RF characteristics were found to be suitable for the volunteer study. The signal-to-noise intrinsic to 7.0T together with the coil performance afforded a spatial resolution of 1.1 × 1.1 × 2.5 mm3 for 2D CINE FLASH MRI, which is by a factor of 6 superior to standardized CINE protocols used in clinical practice at 1.5T. The 32-channel transceiver array supports one-dimensional acceleration factors of up to R = 4 without impairing image quality significantly.

Conclusion
The modular 32-channel transceiver cardiac array supports accelerated and high spatial resolution cardiac MRI. The array is compatible with multichannel transmission and provides a technological basis for future clinical assessment of parallel transmission techniques at 7.0T.
Y1  - 2013
U6  - https://doi.org/10.1002/mrm.24903
SN  - 1522-2594
VL  - 72
IS  - 1
SP  - 276
EP  - 290
PB  - Wiley-Liss
CY  - New York
ER  -