Effect of Polymeric Moisture Barriers on ZnO Nanofiber Gas Sensors Operating at Room Temperature

Relative humidity is a significant factor that impairs gas sensor performance. Some investigations have heated sensors to temperatures beyond 100 °C to eliminate relative humidity, negatively affecting the sensor stability and application range. To improve the sensitivity of gas sensors that operate at room temperatures, free-standing polymer films with moisture barrier qualities are applied to various sensor architectures. A selective permeable polymer membrane applied to the air interface of the sensors, with or without contact, is intended to lessen the effects of relative humidity on sensor sensitivity. In this study, ZnO structures were synthesized by using electrospinning methods. Selective permeable polystyrene/poly(ethylene glycol) (PS/PEG) polymer film membranes were produced on the synthesized nanofiber structures and applied to the sensor. In the membrane synthesis, the CO₂ annealing process was applied to control the porosity O₂ and moisture permeability. Gas sensor performance tests for NO₂ and H₂ gases were conducted for these synthesized nanostructures and membranes by using various characterization techniques and analyses. Gas-sensing measurements were performed in dry air and a relative humidity (RH) of 50%, employing different concentrations of NO₂ and H₂ gases. Different sensing parameters (response time, recovery time, sensitivity) were estimated at room temperature for samples, and the sensor sensitivity was 0.0152 at 50 ppm. Sensor response is enhanced approximately fivefold by samples with polymeric membrane measurements compared to without. Nanofibers exhibit 120 and 300 s response time and recovery time for NO₂ gas, respectively. As a result, a new approach to the literature has been provided to reduce the effects of RH on the sensor, which is one of the biggest obstacles in the scope of gas sensors operating at room temperature. Therefore, this study's findings open a general approach for fabricating flexible devices for gas detection applications.