Singh Harinder, Kumar Akshay, Bansod Babankumar S, Singh Tejbir, Thakur Anup, Singh Tarandip, Sharma Jeewan
Department of Nanotechnology, Sri Guru Granth Sahib World University Fatehgarh Sahib 140 407 India
Central Scientific Instruments Organization Chandigarh 160 030 India.
RSC Adv. 2018 Jan 19;8(7):3839-3845. doi: 10.1039/c7ra10917b. eCollection 2018 Jan 16.
This work reports the enhancement in sensitivity of a simple and low-cost capacitive moisture sensor using a thin film of zinc oxide (ZnO) nanoparticles on electrodes. The ZnO nanoparticles are systematically characterized using X-ray diffraction, atomic force microscopy, transmission electron microscopy, BET surface area analysis, Fourier transform infrared spectroscopy, and UV-visible and photoluminescence (PL) spectroscopy. The average crystallite size of the ZnO nanoparticles is ∼16 nm with a surface roughness of ∼3 nm. Blue emission in the PL spectrum confirms the presence of oxygen vacancy dipoles, which are responsible for enhancing the dielectric properties of the ZnO nanoparticles. The effect of the ZnO nanoparticles on the sensitivity of a moisture sensor cell has been studied using wheat grains with a moisture content from 7% to 25%. An enhancement in sensitivity of 36.4% at 1 MHz and 97.4% at 500 Hz has been observed. A detailed sensing mechanism is proposed and the enhancement in sensing has been explained based on the interaction of ZnO with water vapor and the dielectric behavior of the nanostructured ZnO. The present results establish ZnO as a sensing material for improving the utility of moisture sensors.
这项工作报道了一种简单且低成本的电容式湿度传感器灵敏度的提高，该传感器在电极上使用了氧化锌（ZnO）纳米颗粒薄膜。使用X射线衍射、原子力显微镜、透射电子显微镜、BET表面积分析、傅里叶变换红外光谱以及紫外可见和光致发光（PL）光谱对ZnO纳米颗粒进行了系统表征。ZnO纳米颗粒的平均微晶尺寸约为16 nm，表面粗糙度约为3 nm。PL光谱中的蓝色发射证实了氧空位偶极子的存在，这些偶极子负责增强ZnO纳米颗粒的介电性能。使用含水量为7%至25%的小麦籽粒研究了ZnO纳米颗粒对湿度传感器单元灵敏度的影响。在1 MHz时灵敏度提高了36.4%，在500 Hz时提高了97.4%。提出了详细的传感机制，并基于ZnO与水蒸气的相互作用以及纳米结构ZnO的介电行为解释了传感增强现象。目前的结果确立了ZnO作为一种用于提高湿度传感器实用性的传感材料。
