應用熱磁電耦合技術所建構之微型能源擷取器與磁感測器

Abstract

近期，無線感測器以及無線感測網路蓬勃發展，並使用於各種無線感測的應用之中。然而，市售的無線感測器皆是使用電池做為能量供給，無線感測器在長時間使用後，必須將電池充電或是更換電池，因此開發出能擷取環境物理量轉換成電能之能源擷取器，作為無線感測器之能量來源，為目前發展的趨勢。 其中，若能將環境之物理量以很高的轉換效率轉換成電能，則可以作為能源擷取器，並驅動無線感測器，如果環境之物理量轉換成電能的效率不高，但靈敏度很高時，依然可以當作監測環境物理量之感測器來使用。 本論文利用熱磁電耦合技術，開發出能擷取環境之磁能、熱能物理量之熱磁式能源擷取器，擷取環境電磁能時，最大可輸出20 mV之電壓，擷取環境熱能時，最大可輸出70 mV之電壓。利用與能源擷取器相同之架構，製作了可利用熱能輔助作為重置開關之微型磁感測器，其量測結果，可量測之磁場範圍20~45高斯，磁場頻率10~500 Hz，靈敏度(Sensitivity)為64 nV/Gauss，解析度(Resolution)為0.4 Guass，精確度(Accuracy)為4%。

In this thesis, an innovative thermal-magnetic-piezoelectric multi-coupled technology is utilized to develop a miniature energy harvester and magnetic sensor. Due to the multi-coupling, the energy harvester is capable of harnessing the ambient magnetic and thermal energy and consequently convert the energy to piezoelectric voltage-response. Under an alternative magnetic field of 3.5 Oe and temperature-difference of 25 ˚C, the maximum piezoelectric voltage output produced by the harvester is 20 mV and 70 mV, respectively. Furthermore, through using the similar configuration, the energy harvester can be used as a magnetic sensor. To demonstrate the magnetic sensing through the similar configuration, millimeter-scale and micro-scale magnetic sensors are fabricated by conventional machining and MEMS-processing technology, respectively. The experimental results show the sensing-range, frequency-bandwidth, sensitivity, resolution and accuracy of the micro-scale magnetic sensor under an AC magnetic field of 45 gauss is 20-45 gauss, 10-500 Hz, 64 nV/gauss, 0.4 guass, and 4%, respectively. Due to the multi-coupling, the sensor also demonstrates a novel thermal-reset approach which are comparable with the conventional coil-reset approaches used by the conventional magnetic-domain-based AMR magnetic sensors.