ZnO nanoparticles-based vacuum pressure sensor

ZnO nanoparticles synthesized using the sol-gel technique with an average diameter of 11.5 nm are used to fabricate a vacuum pressure sensor in the range of 1 mbar to 10+3 mbar (low vacuum limit). A drastic increase in the current of the drop-casted ZnO on glass with 30 µm separated Au contacts defined by e-beam lithography is observed. The sensor reveals a linear relationship in current versus pressure in a logarithmic plot. In the range of 1 mbar to 10+3 mbar, the sensor sensitivity is found be 110. Using the resistance-time plot of the vacuum pressure, the rise (response) and fall (recovery) times of the sensor are determined as 6.6 and 15.6 s, respectively. The power consumption of the sensor is 6.5 W. The operational parameters of the proposed sensor are found be much better than those of previously reported ZnO nanostructure-based sensors and, indeed, traditional ones. The sensing mechanism of the sensor is explained by the adsorption/desorption of OH− ions from the surface of the ZnO nanoparticles, leaving behind oxygen ions combined with oxygen vacancy states.