Thermal Convection Inclinometer and Angular Accelerometer Design and Analysis

• Main Authors: Lin-Chia-Hsien, 林佳賢
• Other Authors: Jium-Ming-Lin
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/09658191643507437900

碩士 === 中華大學 === 電機工程學系碩士班 === 102 === This paper presents a novel method to apply a simple and low costprocess to make thermal convective inclinometer and angular accelerometer.They are implemented directly on a flexible substrate and integrated with an active RFID tag, such that they become wireless inclinometer and angular accelerometer. This research applied anew hemi-cylindrical or a hemi-spherical chamber instead of the traditional rectangular one, it is found that step-input response time is faster by using the hemispherical chamber, and the sensitivity is also better than the traditional rectangular type. Besides, the inert gas “xenon” is proposed to replace the traditional filling gas, such as carbon dioxide.Because xenon has molecular weight (132g/mol) three times more than carbon dioxide (44g/mol), when the device is inclined, then thecarbon dioxide hits the wall of the chamber and causes a larger reflective signal, thereby destabilizing the response time and sensitivity of the device. However, this phenomenon occurs less by the use of “xenon gas”. In addition, simulation result shows that if a layer of aluminium nitride material is stacked under the temperature sensor, then the device can yield larger sensitivity than the traditional floating and non-floating structures without the stacking layer. In summary, the process of fabricating the non-floating-type is simple and chip, and the performance is also better. The above new ideas are also applied for the design of an angular accelerometer. The sensitivity and the step-input responses by using the hemispherical chamber are larger and fasterthanthat obtained by the traditional rectangular chamber with floating structure, thus the non-floating hemispherical angular accelerometer is a better choice. Furthermore, investigations were also made for temperature sensors placed in a non-parallel manner, unlike the conventional parallel structure. The results by using the conventional parallel structure shows that the sensitivity curve has a maximum temperature difference at input angular acceleration of 13.04*10-3rad/sec2, and then drops to a lower value. In contrast, the non-parallel structure can provide a more linear and smooth sensitivity curve without maxima peak problem, thereby this is a new discovery of this research.