Verma Rajni, Pathak Saurabh, Dey Kajal Kumar, Sikarwar Samiksha, Yadav B C, Srivastava A K
School of Physics, The University of Melbourne Parkville VIC 3010 Australia
Department of Mechanical Engineering, The University of Melbourne Parkville Victoria 3010 Australia.
Nanoscale Adv. 2022 Jun 8;4(13):2902-2912. doi: 10.1039/d1na00893e. eCollection 2022 Jun 28.
Variation in the transmitted light intensity from metal oxide thin films with moisture content provides a great opportunity to use them for humidity sensing. Herein, we have developed a novel and simple humidity sensor based on ZnO nanorod (ZNR) thin films which work as transmission-based sensing elements in an in-house fabricated sensing setup. The ZNR sensing element shows excellent linear sensing performance in the relative humidity (RH) range 10-90% and does not show any hysteresis. A maximum change in optical power of ∼95 μW is observed with the change in RH in the range 10-90%, for the sample with the smallest crystallite size (ZNR1) and highest pore diameter of the ZNR film. Also, a maximum sensitivity of 1.104 μW/% RH is observed for the ZNR1 sample which drops to 0.604 μW/% RH for the highest crystallite size sample (ZNR4). The presence of oxygen vacancies and the micro-porous nature of the film allow the absorption of water vapour on the film which deflects light at different angles that vary with the moisture content. The experimental results suggest that the ZNR film with a smaller crystallite size and larger pore diameter is more sensitive for humidity measurements. Further, an improved sensing performance is perceived in ZNRs because of the larger surface area of the nanorods. The ZNR based sensing elements do not suffer from ageing effects and exhibit high repeatability (88.74%). Further, the humidity sensor has a response time of 62 seconds and recovery time of 100 seconds which can be considered as a fairly quick response.
金属氧化物薄膜的透射光强度随水分含量的变化为将其用于湿度传感提供了绝佳机会。在此，我们基于氧化锌纳米棒（ZNR）薄膜开发了一种新颖且简单的湿度传感器，该薄膜在内部制造的传感装置中用作基于透射的传感元件。ZNR传感元件在10 - 90%的相对湿度（RH）范围内表现出优异的线性传感性能，且无任何滞后现象。对于微晶尺寸最小（ZNR1）且ZNR膜孔径最大的样品，在10 - 90%的RH范围内，随着RH的变化，观察到光功率的最大变化约为95 μW。此外，ZNR1样品的最大灵敏度为1.104 μW/%RH，而对于微晶尺寸最大的样品（ZNR4），该灵敏度降至0.604 μW/%RH。氧空位的存在以及薄膜的微孔性质使得水蒸气能够吸附在薄膜上，从而使光以不同角度发生偏转，这些角度随水分含量而变化。实验结果表明，微晶尺寸较小且孔径较大的ZNR膜对湿度测量更为敏感。此外，由于纳米棒的表面积较大，ZNR的传感性能得到了改善。基于ZNR的传感元件不受老化影响，具有高重复性（88.74%）。此外，该湿度传感器的响应时间为62秒，恢复时间为100秒，可认为响应相当迅速。
