Kan Hao, Li Min, Li Hui, Li Chong, Zhou Jian, Fu Chen, Luo Jingting, Fu Yongqing
Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Optoelectronic Engineering, Shenzhen University 518060 Shenzhen China
Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University 518060 Shenzhen China.
RSC Adv. 2019 Nov 26;9(66):38531-38537. doi: 10.1039/c9ra06385d. eCollection 2019 Nov 25.
Having a large surface area, like the quantum confinement effect also caused by the nano-level size of quantum dots (QDs), creates fantastic potential for humidity sensing. A high concentration of surface adsorption sites initiates an increased response. Porosity between QDs allows fast water vapor penetration and outflow. Here, a quartz-crystal microbalance (QCM) humidity sensor was prepared using indium oxide (InO) QDs, synthesized a solvothermal method. After the InO QDs were directly spin-coated onto the QCM, an annealing process removed organic long chains and exposed more moisture adsorption sites on the surfaces of the QDs. The annealed QCM humidity sensor exhibited high sensitivity (56.3 Hz per %RH at 86.3% RH), with a fast response/recovery time (14 s/16 s). Long carbon chains were broken down, and hydrogen-bonded hydroxyl groups were chemisorbed to the QDs. The chemical reaction was reduced by these chemisorbed hydrogen-bonded hydroxyl groups. Mass change was mostly caused by fast multilayer physisorption. Thus, the transducer can effectively and precisely monitor the moisture from a person's breath. InO QD-modified QCM sensors demonstrate promising humidity-sensing applications in daily life.
具有较大的表面积，如同量子点（QDs）的纳米级尺寸所引起的量子限制效应一样，为湿度传感创造了巨大潜力。高浓度的表面吸附位点引发了更高的响应。量子点之间的孔隙率允许水蒸气快速渗透和流出。在此，使用溶剂热法合成的氧化铟（InO）量子点制备了一种石英晶体微天平（QCM）湿度传感器。将InO量子点直接旋涂到QCM上后，退火过程去除了有机长链，并在量子点表面暴露出更多的水分吸附位点。退火后的QCM湿度传感器表现出高灵敏度（在86.3%RH时为每%RH 56.3 Hz），响应/恢复时间快（14 s/16 s）。长碳链被分解，氢键结合的羟基化学吸附到量子点上。这些化学吸附的氢键结合羟基减少了化学反应。质量变化主要由快速的多层物理吸附引起。因此，该传感器能够有效且精确地监测人体呼出的水分。InO量子点修饰的QCM传感器在日常生活中展示了有前景的湿度传感应用。
