Development of Pyroelectric Temperature Sensor Based on Cantilever Beam

• Main Authors: Ming-Shian Su, 蘇銘絃
• Other Authors: Yuh-Chung Hu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/55939943017682283877

碩士 === 華梵大學 === 機電工程研究所 === 93 === The development of the infrared sensor based on cantilever beam is carried out by using the pyroelectric response of ZnO to the temperature. The device is fabricated by MEMS processes. The Si3N4 and the controlled thickness Si is used as cantilever beam whereupon is the sensor element including a sandwich of electrodes and a sputtering ZnO layer. Several groups of the sensors with various layer thickness, effective area, partially and fully covered electrode were fabricated and investigated. A systematic study of the process parameters on the pyroelectric responsivity is thus performed for the improvement of the infrared sensor. The measured data shows that the partial-electroded sensors exhibits better responsivity than those with conventional fully covered electrodes and can be used for the detection of infrared emitted from human body. Furthermore, it is necessary to modulate the incident infrared for monitoring the temperature history of the body. Instead of mechanical chopper, a piezoelectric stage is used to excite the cantilever beam to a certain frequency, and the sensing element can thus move relative the infrared source by the frequency. The device can thus be further miniaturized, and the vibration of the cantilever beam can have higher modulation frequency than the mechanical chopper. Meanwhile, the resonance frequency of the cantilever beam can be determined by the sizes of the beam, and the maximum piezoelectric voltages occur at those frequencies. The voltages show maximum values at the third mode for each cantilever beam when they were excited to the third mode. It is also reveals that the chopping method through vibration of the cantilever beam can monitor temperature change of the infrared source.