Surface Functionalized Sensors for Humidity‐Independent Gas Detection

Abstract

Semiconducting metal oxides (SMOXs) are used widely for gas sensors. However, the effect of ambient humidity on the baseline and sensitivity of the chemiresistors is still a largely unsolved problem, reducing sensor accuracy and causing complications for sensor calibrations. Presented here is a general strategy to overcome water‐sensitivity issues by coating SMOXs with a hydrophobic polymer separated by a metal–organic framework (MOF) layer that preserves the SMOX surface and serves a gas‐selective function. Sensor devices using these nanoparticles display near‐constant responses even when humidity is varied across a wide range [0–90 % relative humidity (RH)]. Furthermore, the sensor delivers notable performance below 20 % RH whereas other water‐resistance strategies typically fail. Selectivity enhancement and humidity‐independent sensitivity are concomitantly achieved using this approach. The reported tandem coating strategy is expected to be relevant for a wide range of SMOXs, leading to a new generation of gas sensors with excellent humidity‐resistant performance.

Water-Selective Nanostructured Dehumidifiers for Molecular Sensing Spaces

“…6−9 In addition, a water vapor concentration for a typical relative humidity (RH) range (20−80%) is equivalent to 6000−25 000 parts per million (ppm) under 1 atm and 25 °C, which is clearly much higher than the conventional concentration range (from the parts per trillion to the ppm level) of volatile organic compound (VOC) analytes. 10,11 Thus, suppressing the moisture effect is strongly required for various sensors regardless of their sensing principles. 3,12−14 Substantial progress has been made through various approaches to suppress such water poisoning effects on sensor properties.…”

Mesoporous titanium niobium nitrides supported Pt nanoparticles for highly selective and sensitive formaldehyde sensing

“…For practical applications, poor selectivity in complex detection scenarios is prone to false alarms. 54 Fig. 4d shows transient response of Pt/Ti 0.75 Nb 0.25 N to 50 ppm formaldehyde and a mixture of 50 ppm formaldehyde and 50 ppm interfering gas.…”

Metal Nanoclusters/Polyvinyl Alcohol Composite Films as the Alternatives for Fabricating Remote-Type White Light-Emitting Diodes

“…The direct contact to the UV chips results in continuous heat, and further leads to the phase separation, color inhomogeneity and efficiency deterioration [23][24][25][26][27]. Packaging the MNCs into polymers offers the possibility to overcome the above-mentioned shortcomings [28][29][30]. Polyvinyl alcohol (PVA) is a commercialized polymer, which has been widely used as polarizer in the liquid crystal imaging system and approved by the USA Food and Drug Administration (FDA) for medical applications [31][32][33][34].…”