Three sizes of CuO nanosheets were synthesized by hydrothermal method. The structure and morphology of CuO nanosheets were characterized by X-ray diffraction and scanning electron microscopy. Dielectrophoresis nano-manipulation technique was employed to arrange the materials on pre-designed Ti/Au electrodes to fabricate the three humidity sensors, and the sensing properties were then tested. The experimental results show that the sensitivity greatly increases with the decreasing size of CuO nanosheets, the sensitivity of sensor a, b, c are 369%, 3278%, 22,611% in 97.3% RH, respectively. The smaller sized CuO nanomaterials have better response characteristic, the response time of sensor a, b, c under 11.3–97.3% RH are 53 s, 49 s, 32 s, respectively. And correspondingly, hysteresis properties and the repeatability are also a little influenced. In addition, based on complex impedance spectroscopy and multilayer adsorption theory, the impact of size on humidity sensing property was discussed. The results indicated the feasibility to obtain higher performance of humidity sensor, especially the higher sensitivity, via employment the smaller size sensing nanomaterials.

中文翻译：

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尺寸对氧化铜纳米颗粒湿度感测性能的影响

通过水热法合成了三种尺寸的CuO纳米片。用X射线衍射和扫描电子显微镜对CuO纳米片的结构和形貌进行了表征。采用介电电泳纳米处理技术将材料布置在预先设计的Ti / Au电极上，以制造三个湿度传感器，然后测试其传感性能。实验结果表明，随着CuO纳米片尺寸的减小，灵敏度大大提高，在97.3％的相对湿度下，传感器a，b，c的灵敏度分别为369％，3278％，22611％。尺寸较小的CuO纳米材料具有较好的响应特性，在11.3–97.3％RH下传感器a，b，c的响应时间分别为53 s，49 s，32 s。相应地，磁滞特性和可重复性也受到一些影响。此外，基于复阻抗谱和多层吸附理论，讨论了尺寸对湿度感测性能的影响。结果表明，通过使用较小尺寸的感测纳米材料，可以获得更高性能的湿度传感器，尤其是更高的灵敏度的可行性。