Humidity sensors are widely used in the Internet of Things (IoT). According to the requirements of medical respiratory monitoring, non-contact sensing, and human-machine interface, fast response and high repeatability are crucial for efficient and accurate signal acquisition. Previous research has mainly focused on improving sensitivity, while weakening response time, stability, and repeatability. In this article, researchers such as Wang Xiaoyi from Beijing Institute of Technology and Gao Feng from Zhejiang University published a paper titled "A High Performance Surface Acoustic Wave Humidity Sensor with Uniform Multilayer Graphene Oxide Film" in the ACS Sens journal. They studied the use of uniform wrinkled graphene oxide (GO) thin films obtained by vacuum filtration and liquid-phase transfer methods as sensing materials, and proposed a surface acoustic wave (SAW) humidity sensor with comprehensive performance. The multi wrinkled graphene oxide film has the characteristics of controllable thickness (as thin as 29 nm), uniform wafer manufacturing (2 inches), and abundant wrinkles. Due to its large number of water molecule adsorption sites and transmission channels, it has become an effective sensitive film for surface acoustic wave humidity sensors. The experimental results show that the sensor can achieve high sensitivity (10.5 kHz/RH% @ 60 nm thick film), ultra fast response (about 45 ms), good stability (variation amplitude of about 0.1%), repeatability (variation amplitude of about 1%), and wafer level manufacturing capability, indicating its practical application value in medical respiratory monitoring, non-contact sensing, and human-machine interface.

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