An extended gate FET-based biosensor integrated with a Si microfluidic channel for detection of protein complexes

In this work, we present an extended gate field effect transistor (EGFET)-based biosensor integrated with a silicon micro-fluidic channel for the electronic detection of streptavidin–biotin protein complexes. The connection between the EGFET and microfluidic system could be achieved with the proposed device, as it offers isolation between the device and solution, compatibility with the integrated circuit (IC) technology and, is applicable to the micro total analysis system (μ-TAS). The device was fabricated on the basis of semiconductor IC fabrication and micro-electro mechanical system (MEMS) technology. Au was used as the extended gate metal to form a self-assembled monolayer (SAM) with thiol. The bindings of the SAM, streptavidin and biotin were detected by measuring the electrical characteristics of the FET device. We also verified the interactions among the SAM, streptavidin, and biotin by using surface plasmon resonance (SPR) measurements. Furthermore, atomic force microscopy (AFM) images of the bio-layers formed on the Au electrode were taken in a solution in order to determine the presence of protein biomolecules with the proposed configuration.