以壓電式微加工超音波傳感器相控陣列實現三維空間距離感測系統

Abstract

隨著物聯網與工業4.0的時代來臨，傳感器的需求越來越高，不僅如此，近年來超音波感測技術的發展非常迅速，且微機電製程技術也逐漸成熟，使得擁有低成本、低功耗、高輸出且尺寸可微縮的微加工超音波傳感器(PMUT)在各領域中逐漸佔有一席之地，包含消費性電子、車用電子、智慧工廠與醫用超音波等皆可看到超音波的身影，然而，相較於目前市場上常見的超音波產品應用，如：應用在生物組織的醫用超音波探頭和應用在空氣介質中的倒車雷達，目前能在空氣中傳播的超音波陣列雷達技術相較不成熟，因此，本研究將針對頻率亦在kHz的PMUT陣列進行研發，不僅在效能上遠勝超音波單體，更能達成空間中的掃描並實現三維空間距離感測系統。 本論文以三維空間距離感測的應用為目標，致力於開發壓電式微加工超音波傳感器陣列，利用不鏽鋼基板搭配氣膠沉積法來製備壓電厚膜，並透過微機電製程完成元件的製作。該陣列的共振頻率為56.9 kHz，且位於6 cm處時的聲壓位準約為106 dB，並成功驗證了PMUT陣列控制的可行性，而在距離感測的部分，從量測結果中得知本PMUT陣列的最遠感測距離可達3 m，且距離感測誤差在3 %內，最後，再將相控陣列與距離感測之技術相結合即實現三維空間距離感測之目標。

As IoT and Industry 4.0 take center stage, the demand for sensors is growing rapidly. Not only that, ultrasonic sensing technology also has been developing rapidly in recent years. Meanwhile, as the Microelectromechanical system (MEMS) process has gradually matured, the piezoelectric micromachined ultrasonic transducer (PMUT) with low cost, low power consumption, high output performance and miniaturization plays a crucial role in various fields. It is found that ultrasound applications exist everywhere, in consumer electronics, automotive electronics, smart factories and even medical ultrasound. However, compared to common ultrasonic products on the current market, such as medical ultrasound probes applying on tissue and airborne parking sensors, the current technology of airborne ultrasonic array radar is relatively immature. Therefore, this study will focus on developing airborne PMUT array to achieve higher performance than single element and realize spatial scanning by building three-dimensional spatial range detection system. The thesis is dedicated to developing PMUT array based on the applications of three-dimensional spatial range detection. The piezoelectric thick film is fabricated on stainless steel substrate by aerosol deposition method and then use MEMS process to finish the production of devices. The resonant frequency of PMUT array is at 56.9 kHz and the sound pressure level is about 106 dB at 6 cm distance. It also verifies the feasibility of PMUT phased array control. In the section of range detection, the maximum detection range of PMUT array up to 3 m and range error below 3 % by measurement results. Consequently, with the integration of phased array control and range detection technology, it can realize the three-dimensional spatial range detection.