水平式排列奈米碳管叢應變感測器之設計與研究

Abstract

奈米碳管製作應變感測器已有多項研究，但大部分都為單壁奈米碳管或是奈米碳管混合聚合物之研究，鮮少有純粹以多壁碳管薄膜製作感測器的研究。利用微量的奈米碳管與聚合物製作的奈米複合材料來當作應變感測器，皆是利用聚合物本身的穿隧效應來達到電阻變化，卻很少用到奈米碳管本身的優異特性。有部分的文獻使用大量的奈米碳管製作成薄膜，但是薄膜裡的奈米碳管皆是雜亂無序的排列。 本論文利用一種創新之手法來製作奈米碳管的應變感測器，其中有兩個最特別之處，其一是利用丙酮蒸氣使垂直式排列奈米碳管叢倒下形成水平式排列奈米碳管叢，並增加其容積密度。倒下的水平式奈米碳管叢具有排列性，可以提升穩定性和靈敏度，增加水平式奈米碳管叢的容積密度可以使感測器在拉伸的情況下增加水平式奈米碳管之間的接觸形成並聯，使電阻變小。另一個特別之處是在金屬電極上成長奈米碳管叢來連接水平式排列奈米碳管叢的兩端。電極成長的奈米碳管與水平式奈米碳管接觸可以大幅降低接觸電阻，以提升電阻變化率。 本研究製作了不同參數的感測器，並進行了多種的量測，包含了靜態拉伸量測、動態拉伸量測、不同溫度的電阻量測。其中以丙酮蒸氣製作水平式奈米碳管叢，電極用不鏽鋼線成長三層填鐵奈米碳管叢的應變感測器表現最好，其應變規因子可以高達50。此法製作的應變感測器還有許多空間可以再提升靈敏度和穩定性，甚至是大幅縮小感測器之尺寸，以應用在未來各種奈米科技的微小裝置上。

There are many researches about producing strain gauge with carbon nanotubes (CNTs). But most of them are studying single-wall carbon nanotubes or nanocompsites of low loading CNTs and polymer. There are few researches about producing stain gauge with multi-wall carbon nanotubes. In these researches, the resistance change of nanocomposite stain sensors is obtained due to the tunneling effect between adjacent CNTs rather than using the intrinsic characteristics of CNTs. Some of the researches produce strain sensors with film of high loading CNTs, but all carbon nanotubes in films are non-aligned. In this paper, we provide a novel way to produce stain sensors with CNTs. There are two special parts in this work. The first part is self-directed acetone infiltration. It can lay the vertically aligned carbon nanotubes (VA-CNTs) into the horizontally aligned carbon nanotubes (HA-CNTs) and increasing the bulk density of HA-CNTs. Because the CNTs of sensors are aligned, it can improve the sensitivity and stability. Additionally, the large bulk density of HA-CNTs dominates paralleling effect among CNTs under stretching. The resistance of sensors decreases with paralleling contact between HA-CNT and HA-CNT. The other part is growth iron-filled CNTs on electrodes which connect to HA-CNTs. The results decrease the resistance of sensors prominently, and improve the sensitivity of sensors. We produce sensors with different parameters and proceed with multiple measurements on these sensors. Like static measurements, dynamic measurements, and the resistance changes with different temperatures. The best sensors we produced are using the acetone vapor as the self-directed liquid infiltration to turn VA-CNTs into HA-CNTs and growth three layers iron-filled CNTs on electrodes made by stainless steel wires. The gauge factor of the sensors made by this way can reaches about 50. It still has great potential to promote sensitivity and stability, and even decrease the size largely for applications in the future.