Sensing of Oxygen Partial Pressure in Air with ZnO Nanoparticles

Abstract

The demand for sensors in response to oxygen partial pressure in air is increasingly high in recent years and small-size sensors on a micrometer scale and even a nanometer scale are particularly desirable. In this paper, the sensing of oxygen partial pressure in air was realized by a solution-processed ZnO nanoparticle (NP). Thin-film ZnO NP was prepared by spin-coating and a highly sensitive sensor was then fabricated. The oxygen sensing performance was characterized in air and compared with that in nitrogen, which showed an increase in electrical conductance by more than 100 times as a result of decreasing oxygen partial pressure from 103 mBar to 10−5 mBar. Moreover, higher sensitivity was achieved by increasing the annealing temperature and the effect of thermal annealing was also investigated. Furthermore, ZnO NP lines with 7 μm in width were successfully patterned with low cost by a mould-guided drying technique from ZnO NP dispersion, which makes ZnO NP extremely promising for miniaturized and integrated sensing applications.

Photoactivated Processes on the Surface of Metal Oxides and Gas Sensitivity to Oxygen

“…All of these metal oxides demonstrate high photoconductivity when exposed to UV radiation and are often considered as materials for photoactivated gas sensors, both individually and as a component of gas-sensitive nanocomposites (see, for example, the references in [ 15 ]). In particular, the mentioned metal oxides are also considered as oxygen gas sensors [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ], and several papers were recently published on enhancing the sensor response to oxygen under UV activation [ 23 , 24 , 25 , 26 ]. Oxygen detection by metal oxide gas sensors, in addition to the obvious practical application, is the simplest case for modeling various mechanisms of gas sensitivity due to the chemical simplicity of such a two-component system (metal–oxygen).…”

Silica Nanoparticles Coated with Smaller Au Nanoparticles for the Enhancement of Optical Oxygen Sensing

“…Optical oxygen sensors based on the quenching of luminescence emitted from dyes have experienced increasing success in the past decades since their introduction to detecting oxygen. , These optical oxygen sensors exhibit several advantages such as unmatched sensitivity, remote sensing capabilities via fiber optics, noninvasiveness, and low toxicity, − which have been successfully used both in scientific and commercial terms. − However, the response of optical oxygen sensors always faces many problems in actuality when the dye displays weak emission intensity to variations of oxygen concentrations . While, in the vicinity of metal nanostructures, plasmon excitation providing enhanced optical fields can greatly enhance the emission intensity. − Metal-enhanced luminescence (MEL) can not only provide enhanced emissions but also expand the field of dyes by incorporating weak quantum emitters, which has been proved to be an efficient method to increase luminescence sensitivity and intensity in optical oxygen sensors. − Chu’s group fabricated a metal-enhanced optical oxygen sensor.…”