Centre for Intelligent Sensing Technology, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China.
Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore.
Sensors (Basel). 2018 Dec 10;18(12):4352. doi: 10.3390/s18124352.
A novel relative humidity sensor that is based on a linear piezoelectric micromachined ultrasonic transducer (pMUT) array was proposed and microfabricated for high sensitivity, fast response, and good stability. The humidity-sensitive graphene oxide (GO) film was deposited on the pMUT array with a facile drop-casting method and characterized by scanning electron microscope (SEM), atomic force microscope (AFM), and Fourier transform infrared spectrum (FTIR). With the humidity level ranging from 10% to 90% RH, the sensor exhibited a high sensitivity of 719 Hz/% RH and an extremely high relative sensitivity of 271.1 ppm/% RH. The humidity-sensing results also showed good short-term repeatability and long-term stability, fast response and recovery, and low hysteresis. Moreover, the temperature coefficient of frequency (TCF) of the present humidity sensor was investigated and it could be easily compensated owing to the pMUT array structure design. This work confirmed that the GO functionalized pMUT is an excellent candidate in humidity detection and it may enable many potential applications, such as ultrasensitive mass detection and simultaneous detection of multiple parameters.
提出并微制造了一种基于线性压电微机械超声换能器（pMUT）阵列的新型相对湿度传感器，以实现高灵敏度、快速响应和良好的稳定性。通过简单的滴铸法将湿敏氧化石墨烯（GO）薄膜沉积在 pMUT 阵列上，并通过扫描电子显微镜（SEM）、原子力显微镜（AFM）和傅里叶变换红外光谱（FTIR）进行了表征。在湿度水平为 10%至 90%RH 的范围内，传感器表现出 719 Hz/%RH 的高灵敏度和极高的相对灵敏度 271.1 ppm/%RH。湿度传感结果还显示出良好的短期重复性和长期稳定性、快速的响应和恢复以及低滞后性。此外，还研究了本湿度传感器的频率温度系数（TCF），由于 pMUT 阵列结构设计，它可以很容易地进行补偿。这项工作证实了功能化 pMUT 的 GO 是湿度检测的优秀候选者，它可能会实现许多潜在的应用，如超灵敏质量检测和多个参数的同时检测。
