RESISTIVE SENSOR FOR DETECTION OF NOBASED ON A RGO/ZNO NANOCOMPOSITE

摘要

The invention relates to a resistive sensor for detection of NO, based on an rGO/ZnO nanocomposite, which operates at the ambient temperature, with applications in the field of monitoring pollution degree in atmosphere and in industrial and domestic environment. According to the invention, the sensor consists of a sensitive element (ES) containing a substrate made of a printed circuit board on which an interdigital grid consisting of some spur pairs is applied, the spurs being made of Ag paste, by photolithographic technique, over which a sensitive material is deposited, the material having a composition comprising ZnO additivated with 10% graphene oxide reduced by heat treatment at a temperature in the range of 120°C...250°C, the direct forbidden region of ZnO being reduced by doping with 10% rGO, and an electronic block for conditioning the signal generated by the sensitive element (ES), comprising a Wheatstone bridge having on one of its legs the sensitive element (ES) itself which exhibits a resistance R=100 k Ω for an NOconcentration of zero ppm, while on the other three legs it has placed some resistors with a fixed value of resistance R, irrespective of the NOconcentration, a source of excitation direct voltage Uconnected to one of the bridge diagonals, an operational instrumentation amplifier (InAmp) with programmable resistor which outputs a signal Utaken over from the Wheatstone bridge, signal which is linearized by means of an analogue multiplier which outputs a voltage U, where a fraction β of the voltage Uis applied to one of the inputs (Y) of the analogue multiplier by means of a potentiometer (P).