A novel GaN-based multiparameter sensor system for biochemical analysis

GaN and its ternary alloys offer several advantages for the fabrication of biochemical sensors systems due to their chemical stability and optical transparency. We employ ion-sensitive field effect transistors (ISFET) based on a surface sensitive AlGaN/GaN heterostructure. Combined with a pico-liter dosing system, an integrated micro reference electrode and an optical spectroscopy system a novel multi-parameter analysis system for aqueous solutions in the micro- to nanoliter range was constructed. Application examples are presented to illustrate the application potential of the sensor system e.g. in the high-throughput screening of cancer drugs. Simultaneous opto-electrochemical monitoring of enzyme reaction kinetics by pH and absorption measurements in 700 nl and parallel automated measurements with functionalized enzyme-modified FETs (EnFET) and a reference ISFET in 3 mu l are demonstrated. The experimental data obtained agree well with published values for the reaction kinetic and with reference measurements performed with a state-of-the-art pH-meter and spectrophotometer which require 1000-fold larger volumes.