P2.5.2 Electrical Monitoring of Layer-by-Layer Adsorption of Oppositely Charged Macromolecules by Means of Capacitive Field-Effect Devices

14th International Meeting on Chemical Sensors - IMCS 2012
2012-05-20 - 2012-05-23
Nürnberg/Nuremberg, Germany
P2.5 FET-based Sensors
M. Weil - Institute of Nano- and Biotechnologies (INB), FH Aachen (Germany), A. Poghossian, M. Schöning - Peter Grünberg Institute (PGI-8), Research Centre Jülich GmbH (Germany), A. Cherstvy - Max-Planck Institute for the Physics of Complex Systems (Germany) and Institute for Physics and Astronomy, University of Potsdam (Germany)
1575 - 1578


Field-effect-based semiconductor devices for the label-free detection of molecular interactions represent a promising platform for biosensor applications. However, a quantitative physical understanding of experimental observations is still not complete in many situations. Therefore, it is important to elucidate the possibilities and limitations of field-effect sensors for the detection of charged macromolecules. In this work, a capacitive electrolyteinsulator-semiconductor field-effect sensor has been applied for real-time in-situ electrical monitoring of a layer-bylayer build-up of polyelectrolyte multilayers. The thickness of polyelectrolyte layers and changes in the surface morphology after the adsorption of each polyelectrolyte layer has been studied by ellipsometry and scanningelectron microscopy. Reproducible oscillations of the sensor signal have been observed upon repetitive alternating adsorption of positively and negatively charged polyelectrolyte layers. To explain signal behaviour of a capacitive field-effect sensor modified with polyelectrolyte multilayers, potential oscillations on the gate surface were simulated using a simplified electrostatic model that accounts for the screening of polyelectrolyte charges by mobile ions within the PEM film.