A novel multivariable system, combining a transistor with fiber optic-based surface plasmon resonance spectroscopy with the gate electrode simultaneously acting as the fiber optic sensor surface, is reported. The dual-mode sensor allows for discrimination of mass and charge contributions for binding assays on the same sensor surface. Furthermore, we optimize the sensor geometry by investigating the influence of the fiber area to transistor channel area ratio and distance. We show that larger fiber optic tip diameters are favorable for electronic and optical signals and demonstrate the reversibility of plasmon resonance wavelength shifts after electric field application. As a proof of principle, a layer-by-layer assembly of polyelectrolytes is performed to benchmark the system against multivariable sensing platforms with planar surface plasmon resonance configurations. Furthermore, the biosensing performance is assessed using a thrombin binding assay with surface-immobilized aptamers as receptors, allowing for the detection of medically relevant thrombin concentrations.

AIT Austrian Institute of Technology GmbH Konrad Lorenz Strasse 24 3430 Tulln Austria

Danube Private University Steiner Landstraße 124 3500 Krems an der Donau Austria

FZU Institute of Physics Czech Academy of Sciences Na Slovance 2 Prague 182 21 Czech Republic

Institute of Science and Technology Austria Am Campus 1 3400 Klosterneuburg Austria

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A hybrid OTFT-SPR system for simultaneous electronic and optical sensing