Shen Wei-Chun, Shih Po-Jen, Tsai Yao-Chuan, Hsu Cheng-Chih, Dai Ching-Liang
Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
Department of Biomedical Engineering, National Taiwan University, Taipei 106, Taiwan.
Micromachines (Basel). 2020 Jan 15;11(1):92. doi: 10.3390/mi11010092.
This study describes the fabrication of an ammonia gas sensor (AGS) using a complementary metal oxide semiconductor (CMOS)-microelectromechanical system (MEMS) technique. The structure of the AGS features interdigitated electrodes (IDEs) and a sensing material on a silicon substrate. The IDEs are the stacked aluminum layers that are made using the CMOS process. The sensing material; polypyrrole/reduced graphene oxide (PPy/RGO), is synthesized using the oxidation-reduction method; and the material is characterized using an electron spectroscope for chemical analysis (ESCA), a scanning electron microscope (SEM), and high-resolution X-ray diffraction (XRD). After the CMOS process; the AGS needs post-processing to etch an oxide layer and to deposit the sensing material. The resistance of the AGS changes when it is exposed to ammonia. A non-inverting amplifier circuit converts the resistance of the AGS into a voltage signal. The AGS operates at room temperature. Experiments show that the AGS response is 4.5% at a concentration of 1 ppm NH; and it exhibits good repeatability. The lowest concentration that the AGS can detect is 0.1 ppm NH.
本研究描述了一种采用互补金属氧化物半导体（CMOS）-微机电系统（MEMS）技术制造氨气传感器（AGS）的方法。AGS的结构特点是在硅衬底上有叉指电极（IDE）和传感材料。IDE是使用CMOS工艺制作的堆叠铝层。传感材料聚吡咯/还原氧化石墨烯（PPy/RGO）采用氧化还原法合成；并使用化学分析电子能谱仪（ESCA）、扫描电子显微镜（SEM）和高分辨率X射线衍射（XRD）对该材料进行表征。在CMOS工艺之后，AGS需要进行后处理，以蚀刻氧化层并沉积传感材料。当AGS暴露于氨气时，其电阻会发生变化。一个同相放大器电路将AGS的电阻转换为电压信号。AGS在室温下工作。实验表明，在1 ppm NH₃浓度下，AGS的响应为4.5%；并且它具有良好的重复性。AGS能够检测到的最低浓度为0.1 ppm NH₃。
