High sensitivity AlGaN/GaN field effect transistor protein sensors operated in the subthreshold regime by a control gate electrode

We demonstrate high sensitivity AlGaN/GaN field effect transistor biosensors with a control gate electrode for streptavidin detection. The device active area is functionalized with 3-Aminopropyltriethoxysilane and N-hydroxysulfosuccinimide-biotin for streptavidin binding. Without any electrochemical side effects, a gate voltage is applied through a Pt control electrode to the solution so that the device operates sensitively in the subthreshold regime. Due to the logarithmic relationship between the channel current and gate voltage in the subthreshold regime, at a concentration of 4.73 pM streptavidin, the device exhibits 9.97% current change in the subthreshold regime compared with the current in phosphate buffered saline solution. In the linear regime, the current change is 0.49% at the same streptavidin concentration. (C) 2011 American Institute of Physics. [doi:10.1063/1.3600063]