An FET-type gas sensor with a sodium ion conducting solid electrolyte for CO2 detection

Abstract

In this paper, a Field-Effect-Transistor (FET)-type gas sensor using the composite of Na2CO3 and NaNO2 as the sensing material is investigated. The sensor has a floating gate (FG) passivated by an insulator stack and a control gate (CG), which are formed in an interdigitated form in a horizontal direction. The inkjet printing process forms the sensing material on the interdigitated FG and CG. Just before forming the sensing material, a (3-aminopropyl) triethoxysilane (APTES) monolayer is formed to prevent diffusion of Na+ ions contained in the sensing material through the insulator layer. The sensor can be electrically programmed like a typical memory device due to the FG, which makes the calibration of the sensor possible. CO2 gas sensing properties of the sensor are characterized at an operating temperature of 160 °C. The results indicate that the proposed sensor produces a reasonable and repeatable response to a certain concentration of CO2.