| Summary: | 碩士 === 國立中山大學 === 電機工程學系研究所 === 99 === This thesis aimed to develop a novel micro thermal electric generator (μ-TEG) with a series-array bridge microstructure utilizing microelectromechanical systems (MEMS) technology. By integrating the tens of thousands of micro-thermocouple in a centimeter square area, the temperature difference between the hot plane and cold plane of the presented μ-TEG can be converted into a useful electrical power. The thermoelectrically transferred output electrical power is suitable for recharging various mobile communication products.
There are two main configurations of the conventional μ-TEGs have been proposed, including the vertical and lateral structure types. The heat flow of the vertical-type μ-TEG can be directly transferred by the thermocouples and hence the energy loss through the substrate can be efficiently reduced and the thermoelectrical conversion efficiency is usually higher than vertical-type μ-TEG. However, to obtain a useful electrical power output, the height of the vertical-type μ-TEG usually more than 100 micrometers and this will increase the production difficulty and fabrication cost. In contrast, the height of the lateral-type μ-TEG is only about several micrometers and hence the production difficulty and fabrication cost are lower than vertical-type μ-TEG. The non-neglect energy loss through the substrate of lateral-type μ-TEG will constrain the efficiency of electrical power generation. Using the surface micromachining technology, tens of thousands of suspending micro polysilicon thermocouple are integrated and serially connected to increase the efficiency of electrical power generation and reduce the substrate energy loss. The main fabrication processes adopted in this research are including seven thin-film deposition processes and five photolithography processes.
The implemented Poly-Si based μ-TEG demonstrates a maximum temperature difference of 1.29℃ between the hot plane and cold plane (under nine different substrate temperatures), a maximum output voltage of 4.47 V/cm2 and a maximum output power of 601.4 nW/cm2. The comparison and analysis of experimental and simulation (ANSYS) results under the nine different substrate temperatures are investigated and the influence of length of suspending micro thermocouples is also discussed in this work.
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