| 摘要: | 微致動器為微機電系統中驅動力的來源，一般區分為熱電式致動器、壓電式致動器、靜電式致動器、電磁式致動器等四種。其中熱電式致動器利用加熱介質(如液體或空氣)，使介質體積變化而產生驅動力，而本實驗使用直徑120μm銅線製作出加熱器並與高分子材料(PDMS)結合製作成Bimorph結構熱致動器，此結構將利用其不同的熱膨脹係數，藉由輸入電壓電流使兩材料產生不同之體積變化，導致熱膨脹係數大端會往熱膨脹係數小端彎曲，並量測其形變量及彎曲角度，進而評估此類微致動器在應用上的可行性。
本文製程首先利用Bimorph形變量公式做分析，設計出微小的熱致動器並能夠在窄小區域內產生致動效果以達到大位移量、低輸出功率之目的，過程中分析數種低楊氏係數金屬材料之優缺點，得出適當之材料與能夠產生大出平面位移量之材料尺寸，並做一系列之實驗以達控制溫度與分析出能適當控制輸入功率所影響PDMS厚度，然後做出加熱器模具，並將PDMS與銅線加熱器結合製成雙層結構懸臂樑熱致動器，製作出之熱致動器經量測能夠控制其形變量及彎取角度，並與理論分析結果做比較。
結果顯示PDMS厚度越大則形變量及彎曲角度均增加，理論公式分析在PDMS厚度631μm與加熱溫度150℃可產生形變量(1.79mm)，而溫度增加將導致形變量減少，而實驗結果PDMS厚度631mm之形變量為1.438mm，
與理論值差距0.35mm，推測為加熱器固化PDMS不均勻與實驗誤差所致，實驗最終將溫度調升至160℃而加熱器將燒毀，故推測此組致動器之加熱極限值於此，未來將調整製程以減少實驗誤差，並提高形變量。
;Microactuators are the source of driving force in MEMS, and are generally classified into four types: thermoelectric actuators, piezoelectric actuators, electrostatic actuators, and electromagnetic actuators. The thermoelectric actuator uses a heating medium (such as liquid or air) to change the volume of the medium to generate a driving force. In this experiment, a heater with a diameter of 120 μm is used to fabricate a heater and combined with a polymer material (PDMS) to form a Bimorph thermal actuators structure, which use different coefficient of thermal expansion to cause different volume changes of the two materials by inputting voltage and current, causing the large end of the coefficient of thermal expansion to bend toward the small end of the coefficient of thermal expansion, and measuring the deformation and bending Angle, and then evaluate the feasibility of such microactuators in application.
The process of this paper firstly uses the Bimorph-shaped variable formula to analyze, designing a tiny thermal actuator and capable of generating an actuation effect in a narrow area to achieve large displacement and low output power. Several low Young′s modulus of material are analyzed in the process.The appropriate material and the size of the material capable of generating large plane displacement, and a series of experiments to control the temperature and analyze the thickness of the PDMS that can properly control the input power, and then make The heater mold is combined with PDMS and copper wire heater to form a bimorph cantilever beam thermal actuator. The thermal actuator can be measured to control its deformation and bending angle, then compare with theoretical analysis results .
The results show that the larger the thickness of PDMS, that the deformation and the bending angle increase. The theoretical formula analysis can produce a deformation (1.79mm) at PDMS thickness of 631μm and a heating temperature of 150°C, while the temperature increase will lead to a decrease in the deformation, and the experimental result shows that the deformation of the PDMS thickness of 631 mm is 1.438 mm, which is 0.35 mm from the theoretical value. The reason is speculated that the heater curing PDMS is uneven and the experimental error is caused.
The experiment finally raises the temperature to 160 ° C and the heater will burn out. Therefore, it is estimated that the heating limit of this group of actuators is here, and the process will be adjusted in the future to reduce the experimental error and increase the shape variable. |
