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AKB: Biologische Physik

AKB 85: Biosensors and Biohybrid Systems

AKB 85.2: Vortrag

Mittwoch, 9. März 2005, 12:45–13:00, TU H2013

Adsorption of Self-Assembled Polyelectrolyte Multilayers on a Silicon-on-Insulator based Sensor Device — •Petra A. Neff, Michael G. Nikolaides, Simon Q. Lud, and Andreas R. Bausch — Lehrstuhl für Biophysik - E22, Technische Universität München, 85747 Garching

Recently, a new Silicon-on-Insulator (SOI) based thin film resistor device for chemical and biological sensor applications was introduced. Its response against pH changes and variations of the salt concentration of an electrolyte on the native oxide surface was measured and compared to the theoretical predictions. It has been shown that the charge of different small peptides or proteins can be determined.

We study the adsorption of polyelectrolyte multilayers onto the SOI sensor devices. During the layer-by-layer deposition of the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly(styrene sulfonate) (PSS) by alternating buffer exchange, the response of a SOI sensor with a native oxide surface was observed as a change in its sheet resistance. The change in surface potential can be calculated from the sheet resistance applying calibration measurements. It corresponds to the surface charge density expected as a result of the multilayer build-up. The sensor signal amplitude was observed to be decreasing linearly with an increasing number of monolayers enabling the detection of more than 20 monolayers. To understand the sensor signal a theoretical model of the properties of the polyelectrolyte layers was compared to the measured data.