具形變感測特性之高分子複合材料微型驅動器

Abstract

本研究提出一種可感測自身形變之可撓式微型驅動器。此驅動器是由兩種不同的軟性高分子材料所組成，分別為以聚二甲基矽氧烷為主體並混有石墨與奈米碳管之導電層以及純聚二甲基矽氧烷絕緣層。此微型驅動器利用兩層材料間之熱膨脹係數差異，再搭配直流電源進行焦耳加熱，即可達成致動之功能。此外，本研究更進一步將石墨與奈米碳管以特定比例調合，中和兩者之電阻溫度係數，達到電阻值幾乎不受溫度影響之效果，使元件具備感測自身形變之能力。實驗量測結果顯示，本研究所提出之元件僅需3V的驅動電壓即可使其致動，且其應變規因子約為本研究所配製之純奈米碳管薄膜的2.6倍，顯示出良好的感測性能。而當元件通電加熱至105°C時，其電阻變化相較於室溫初始電阻值僅上升約1.5%，證實所配製之材料已大幅降低溫度對電阻之影響。此外，在位移回授控制之實驗中，本研究更利用閉迴路系統展示了不管在有無負載的情況下，皆能對元件進行精準的位移控制。實驗結果證實，此微形驅動器將具有實際應用於軟性機器人之感測訊號回饋與動作控制之潛力。

This work proposes a soft microactuator that has the ability to simultaneously sense and actuate merely through two input electric terminals. The proposed device is in fact a simple bilayer electrothermal actuator. The bilayer structure comprises the insulating layer and the conductive layer. The insulating layer is made of polydimethylsiloxane (PDMS)‎ and the conductive layer is composed of graphite microparticles, carbon nanotubes, and PDMS. The working principle of the actuator is based on the bimetallic phenomenon. When the device temperature was elevated by Joule heating, the mismatch of thermal expansion in the structure induces the bending of the structure. Besides, decoupled electrothermal stimulation and strain sensation is achieved by optimizing the ratio of graphite microparticles and carbon nanotubes (CNTs) in the hybrid films. The experimental results show that the proposed device can be driven by low voltages. Additionally, the gauge factor of the proposed device is about 2.6 times higher than that of the pure carbon nanotube thin film prepared in this work. When the device is heated to 105 °C, the resistance increases only about 1.5 percent above that at room temperature. Furthermore, this work also demonstrated a closed-loop system to achieve precision position control with the microactuator under different loads. The approach of the proposed device, which is in fact a simple integrated sensing and actuating mechanism, is a promising way for the developing intelligent soft robots.