具單軸共平面收縮之微結構介電彈性體致動器

Abstract

在本論文中，具單軸共平面收縮之微加工介電彈性體致動器將被提出。同時也會製造及測試致動器並且提出其解析模型。本論文提出的致動器主要是由高分子組成並且利用微機電技術加工完成。當介電彈性體致動器被施加一偏壓時，靜電力將擠壓介電彈性體並因為其內建的微結構造成平面方向的收縮。此致動器由兩層電極、兩層彈性層及一個微結構層所組成。微結構層為柵狀結構並且當作界隔層以定義上下兩層彈性層之間的間隙。此柵狀結構同時決定了共平面的收縮方向。當施加的靜電力將上下兩層彈性層拉近，這兩層彈性層會向內彎曲並且縮短間隔物之間的距離。 本論文將展示兩種不同致動方式的致動器，其中包含彎曲及收縮的致動行為模式。致動器彎曲的致動行為可由設計不對稱的彈性層厚度來達成，相反地，對稱的彈性層厚度將使致動器具備收縮的致動模式。介電彈性體致動器的幾何尺寸(彈性層的厚度與間隔物之間的距離)對致動行為的影響將被探討。並且將以照相機、雷射測距儀及微量天秤量測致動器彎曲及收縮時的自由端撓度、收縮長度及致動力。 本研究以尤拉樑(Euler’s beam)模型及能量法為理論基礎，推導出介電彈性體致動器的撓度解析解，再利用此撓度解析解進一步求得致動器致動時的收縮長度及致動力，並同時以實驗及ANSYS模擬驗證所推導出的理論解析結果。 由於提出的微結構介電彈性體致動器具有輕量、可撓及相對於傳統介電彈性體致動器較低的驅動電壓等優點，因此可應用在人工肌肉上。

In this dissertation, a micromachined dielectric elastomer actuator with uniaxial in-plane contraction was proposed. The modeling, fabrication and testing of the actuator were carried out. The proposed dielectric elastomer actuator was made of polymers by micro-electro-mechanical systems (MEMS) technique. When a bias voltage was applied, the resulting electrostatic force compressed the dielectric elastomer which then shrank in area due to its embedded microstructures. This actuator consisted of two electrode layers, two flexible layers and a microstructural layer, respectively. The microstructural layer possessed the grating patterns which served as the spacers to define the gap between the upper and the bottom flexible layers. The grating patterns also determined the direction of the in-plane contraction. When the applied electrostatic force pulled together the bottom and the upper flexible layers, these two layers bent inwardly and shortened the distance between the spacers. Two actuation types of actuators were demonstrated, which were bending and contraction actuation behaviors. The design of the bending actuation was demonstrated utilizing the asymmetric thickness design of the flexible layers, on the other hand, the actuator with symmetric thickness design of the flexible layers shows contraction actuation. The geometric effects for the actuation behavior of the proposed dielectric elastomer actuator were discussed, including thickness of the flexible layer and the distance between the neighboring spaces. The actuator with bending actuation was measured by CCD camera to detect the free-end deflection, and the actuator with contraction actuation was measured by Laser detector and microbalance to obtain the contraction length and the actuation force. The analytical solution for the deflection of the proposed dielectric elastomer actuator subject to electrostatic loads is derived based on the Euler’s beam model and energy method. Then one can use the closed form solution of the deflection to derive the contraction length and actuation force of the proposed dielectric elastomer actuator. Furthermore, these solution results were verified by ANSYS simulation and experiment. The microstructural dielectric elastomer actuators with lightweight, flexible and relative low driving voltage compared to the conventional dielectric elastomer actuator were designed and demonstrated. Because of these characteristics, the actuators could further be used as artificial muscle.