共振式拉福波震盪器之設計與應用

Abstract

所有表面聲波中，拉福波基於波導層可增強表面橫波能量且可保護交指叉換能器(IDT)，是最適於液體感測。選擇氧化鋅(ZnO)當波導層，拉福波感測器之機電耦合係數與頻率的溫度係數(TCF)都將趨向有利的改善。結合聚二甲基矽氧化硫(PDMS)所製成之流穿式樣品槽於拉福波感測器上，可對集中於兩組交指叉電極間的微量樣品作感測，且可減少液體電性對於電極邊界條件所產生之不良影響。 在本論文，將133MHz石英基材上鍍上氧化鋅(ZnO/ST-cut quartz)之拉福波感測器整合於震盪器，形成拉福波震盪器。拉福波感測器之敏感度值隨著低黏滯性液體會有增加之趨勢，拉福波震盪器的頻率溫度係數為11ppm/℃。為了消除感測時之環境因素影響，諸如溫度、濕度等，應用雙震盪器之電路結構於感測當中。感測裝置用於量測數種甘油與水的不同混合比例，並且量測三次已確定其重複性，實驗結果顯示拉福波感測器適用於低黏滯性之量測。

Among surface acoustic wave (SAW) sensors, Love wave, which is based on the guiding layer can enhance the energy of SH wave and protect IDT, is suited for using in liquid measurement. By choosing ZnO as a guiding layer, the performance of Love wave sensor will be improved including electromechanical coefficient and temperature coefficient of frequency (TCF). The Polydimethylsiloxane (PDMS) flow cell incorporated on Love wave sensor allows a tiny controlled amount of analyte to be confined solely upon the sensing area between IDTs and prevents unwanted electric interactions with IDTS. In this thesis, the 133MHz ZnO/ST-cut Quartz based Love wave sensor was fabricated and integrated the amplifier to form a Love wave oscillator. The sensitivity of Love wave sensor was measured higher with lower viscosity and TCF of our design Love wave oscillator was performed 11ppm/ ℃. Dual oscillator configuration was constructed to eliminate most environment factors such as temperature, humidity and etc. Then, the sensing device was used to measure with various glycerin mixed with DI water. In order to investigate the repeatability performance, all the measurement was done three times. The results show our design Love wave sensor is suitable for low viscosity sensing.