Electrical monitoring of polyelectrolyte multilayer formation by means of capacitive field-effect devices.

Poghossian, A.; Cherstvy, A. G.; Schöning, M. J.

doi:10.1007/s00216-013-6951-9

Journal Article

FZJ-2014-00649

Electrical monitoring of polyelectrolyte multilayer formation by means of capacitive field-effect devices.

Poghossian, A. (Corresponding author)FZJ* ; Cherstvy, A. G. ; Schöning, M. J.FZJ*

2013
Springer Berlin

Analytical and bioanalytical chemistry 405(20), 6425 - 6436 (2013) [10.1007/s00216-013-6951-9]

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Please use a persistent id in citations: doi:10.1007/s00216-013-6951-9

Abstract: The semiconductor field-effect platform represents a powerful tool for detecting the adsorption and binding of charged macromolecules with direct electrical readout. In this work, a capacitive electrolyte–insulator–semiconductor (EIS) field-effect sensor consisting of an Al-p-Si-SiO2 structure has been applied for real-time in situ electrical monitoring of the layer-by-layer formation of polyelectrolyte (PE) multilayers (PEM). The PEMs were deposited directly onto the SiO2 surface without any precursor layer or drying procedures. Anionic poly(sodium 4-styrene sulfonate) and cationic weak polyelectrolyte poly(allylamine hydrochloride) have been chosen as a model system. The effect of the ionic strength of the solution, polyelectrolyte concentration, number and polarity of the PE layers on the characteristics of the PEM-modified EIS sensors have been studied by means of capacitance–voltage and constant-capacitance methods. In addition, the thickness, surface morphology, roughness and wettabilityof the PE mono- and multilayers have been characterised by ellipsometry, atomic force microscopy and water contact-angle methods, respectively. To explain potential oscillations on the gate surface and signal behaviour of the capacitive field-effect EIS sensor modified with a PEM, a simplified electrostatic model that takes into account the reduced electrostatic screening of PE charges by mobile ions within the PEM has been proposed and discussed.

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