具形狀記憶及自感測功能之液晶離子凝膠微型雙穩態元件之開發

Abstract

本研究開發出一具形狀記憶及自感測功能之液晶離子凝膠微型雙穩態元件。此微型雙穩態元件由三個部分構成，分別為具形狀記憶之液晶離子凝膠雙穩態結構、液晶彈性體致動器，以及薄膜加熱器。研究中另以特定比例混入奈米碳管，以降低液晶離子凝膠電阻值，實現自身焦耳加熱，並達成其形狀記憶行為所需之溫度條件。同時利用液晶離子凝膠之電阻值會受到應變影響，使此元件具有判斷其穩態屬第幾穩態之自感測功能。液晶彈性體於本元件中使用電熱致動，一鍍有銅電極之聚醯亞胺薄膜黏附於其上作為加熱源。透過對加熱源通電，液晶彈性體受熱則形變彎曲。同時藉由液晶離子凝膠之形狀記憶特性，當液晶彈性體形變後可對液晶離子凝膠施以外力致使其同樣彎曲形變。待液晶離子凝膠完成形狀記憶行為後，即便沒有受到液晶彈性體之外力，仍能穩定維持其記憶之外形。若再度對液晶離子凝膠加熱，便能回復至初始形狀。這些材料特性與行為除了使此元件能夠順利致動外，還能夠實現雙穩態，並同時具有自感測功能可用以判斷元件屬於何種穩態。本研究進行一系列量測與實驗，驗證此元件可透過形狀記憶特性實現雙穩態，以及具有自感測功能。該微型雙穩態元件只需通過固定電壓，即可驅動液晶彈性體和液晶離子凝膠實現雙穩態。此外，於使用情境中展示了元件利用了雙穩態達成不需供電與外力介入仍能夠持續夾持物體之能力，也具備將持續夾持之物體放置之能力，更透過量測液晶離子凝膠之穩態電阻值可判斷元件屬於第幾穩態。於未來之研究中，藉由進一步量測與探討數據，計算推估夾持物體之相關資訊，對於開發其更完善之感測功能相當具有潛力。

In this study, we present a miniaturized ionogel-based bistable device with sensing capability. The proposed device consists of an ionogel structure with shape memory properties, a liquid crystal elastomers (LCE) actuator, and a thin-film heater. The ionogel structure also possesses strain sensing as well as Joule heating capabilities by dispersing with carbon nanotube (CNT) molecules for enhancing its electric conductivity. The bistability of the device is achieved using the shape memory properties of ionogel. As the temperature of the ionogel structure is above the liquid crystalline transition temperature by Joule heating, the structure becomes deformable. Then, the ionogel structure can be deformed by using the LCE actuator which is thermally driven by the thin-film heater. With the external force exerted by the LCE actuator, the state of the ionogel structure can be preserved as the temperature of the structure returns to room temperature. Also, the state of the bistable ionogel structure can be detected by measuring the resistance change of the structure. In addition, after removing the external force, the bistable structure can retreat to its original state when it is heated again to the liquid crystalline transition temperature. Experimental validation of the bistability of the proposed device was also conducted. The measured relationships between the deformation of the bistable ionogel structure and its resistance change demonstrate that the device possesses the capability of sensing the states of the bistable mechanisms. Furthermore, a demonstration of object grasping and moving by using a gripper consisting of a pair of the bistable structures was presented. With the bistability of the ionogel structures, maintaining the state of object grasping without supplying electric power can be easily achieved.