IGZO MESFET with enzyme-modified Schottky gate electrode for glucose sensing

We describe the development of a glucose sensor through the immobilization of an enzyme (glucose oxidase) into the gate of an In–Ga–Zn–O thin film transistor in a MESFET configuration with Ru–Si–O acting as a Schottky gate electrode. A change in the gate potential, due to a different glucose concentration in the buffer solution causes a change in the width of the depletion region, hence modulating the current in the channel layer. The glucose sensing mechanism of the presented MESFET structure is discussed using energy band diagrams The sensitivity of the fabricated IGZO MESFET biosensor evaluated from the slope of the linear ranges: from 0 to 2 mmol l −1 and from 2 to 10 mmol l −1 , which cover blood, salivary, sudoriferous and lachrymal glucose concentration in humans, equal: 2.23 μ A mmol −1 l −1 and 0.41 μ A mmol −1 l −1 , respectively.