AVS 52nd International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI1-TuA

Paper BI1-TuA4
Gallium Nitride-based BioFETs for Label-free Biosensing

Tuesday, November 1, 2005, 3:00 pm, Room 311

Session: Sensors/Diagnostics
Presenter: K. McCoy, University of Florida
Authors: K. McCoy, University of Florida
J.C. Sullivan, Naval Research Laboratory
J.C. Culbertson, Naval Research Laboratory
E. Snow, Naval Research Laboratory
S.J. Pearton, University of Florida
L.J. Whitman, Naval Research Laboratory
Correspondent: Click to Email
Biologically modified field effect transistors (BioFETs) have the potential to directly detect biochemical interactions in aqueous solutions for a myriad of applications. In order for these devices to be useful, they must satisfy three major criteria. The bioFET must be stable in aqueous solutions across a range of pH and salt concentrations, be sensitive to biochemical interactions on the surface of the device, and be able to probe specific biochemical interactions. BioFETs that we are developing based on AlGaN/GaN quantum well devices can potentially satisfy all of these requirements. These charge-sensitive devices are being functionalized with receptors to stochastically sense the binding of target molecules in aqueous samples. The sensing is based on device geometries whereby the stochastic binding of individual biomolecules above a device will cause a change in conductance. It has already been demonstrated that these AlGaN/GaN quantum well devices can sense small changes in pH of electrolyte solutions. It is our goal to functionalize the surface in such a manner that the sensitivity of the device is not severely reduced. We are evaluating two reaction schemes to accomplish this task. The first involves modifying the surface with a SAM, then attaching a polymer to that SAM which can couple to biological probes. The second method employs a proprietary scheme to functionalize the surface with a layer of avidin that can then be coupled to biotinylated probes. The reaction schemes have been characterized in both UHV (XPS) and solution (cyclic voltammetry, fluorescence microscopy). The effect of these schemes on the electrical properties of the devices will be discussed, along with our progress toward determining the ultimate sensitivity of this biosensor system.