This work shows the possibility of using arrays of ZnO nanorods grown on a glass substrate as a sensitive element of a gas flow velocity sensor.
It has been theoretically shown that when a ZnO nanorod is blown with a gas stream, the temperature of its free end can decrease by 20–40 ° C, which should lead to a change in the resistance of the nanorod material.
Arrays of ZnO nanorods were synthesized on a silicon substrate by the hydrothermal method in an aqueous solution of zinc nitrate and hexamethylenetetramine (C6H12N4) in the temperature range of about 90 ° C for 1-3 h. The formed ZnO nanorods were predominantly vertical with a height of 590-660 nm and had an average transverse size of about 30-40 nm Then, contact metallization of V-Cu-Ni with a thickness of 0.2-0.3 μm was applied over them. The resistance of the obtained samples of sensitive elements ranged from hundreds of ohms to several megohms.
To measure the dependence of the resistance of the ZnO array of nanorods on the gas supply rate, the sample was located in a measuring chamber. The heating temperature of the sample was controlled by a thermocouple and amounted to (200 ° C). Gas was supplied at a speed of 1 to 100 cm / s. The resistance of the sensitive elements, in this case, changed according to a dependence close to linear and increased by 20%. Thus, based on zinc oxide nanorods, a gas flow rate sensor can be built for various applications