混合型石墨烯奈米結構於多工感測器之開發研究

Abstract

可撓式與可穿戴式應變感測器對於人體運動檢測具有無限的潛力，並引起研究人員極大的興趣。在本論文中，我們提出一種以可撓的聚二甲基矽氧烷 (Polydimethyl Siloxane, PDMS) 為基板，加入低成本的石墨烯與石墨烯量子點奈米結構，開發出同時具備應變與光偵測之多工感測器。本研究共分為兩大類，第一部份為拉伸量測以及第二部份為照光量測。第一部份為加入不同次數 (濃度) 的石墨烯進行拉伸量測，在 SEM 拍攝下 20 次數 (濃度) 的石墨烯厚度為 50 μm 和 50 次的石墨烯厚度為 200 μm；在 50 次下所得到的應變因子 (Gauge Factor) 為 GF = 14，在 20 次下得到的應變因子為 GF = 76，並且形變量可以達到 30 % 以上。此外，我們也對該元件進行耐久性測量，以每拉伸 25 次數進行量測，經重複拉伸300次後，其電阻變化率從 4.5 變為 6.5，其改變量約為 14 %。第二部份為加入不同次數的石墨烯與石墨烯量子點進行照光量測，使用波長為 365 nm 的紫外光進行照光量測。發現隨著照光功率提升，電流會從 300 μA 提高至 410 μA，其提升約 30 %。我們預期本論文所開發之混合型石墨烯奈米結構多工感測器，在未來對人體運動檢測上，將能夠發揮重要作用。

Flexible and wearable strain sensors have great potentials for the appliation of human motion detections, and have hence attracted broad research interests. In this thesis, we propose a novel strain sensor combining the graphene flakes with graphene quantum dots on the flexible polydimethylsiloxane (PDMS) substrate. Such novel sensor is able to simutaneously detect the variation of both exerted strain and incident light-power appied on it. The study is mainly divided into two parts: Firstly, we have systematically discussed the dependence of strain variation on a series samples with different times (concentrations) of graphene flakes. The graphene flakes accumulate on the PDMS substrate and form a bulk-like film. According to the corss-sectinal SEM image, the thicknesses are 50 μm and 200 μm for the samples with 20 and 50 times concentrations of graphene flakes, respectively. The measured strain factors are 76 and 20 for the samples with 20- and 50- time concentrations of graphene flakes, respectively. Our stain sensor can sustain upon to the maximum deformation of ~30 %. We also perform the durability test on our strain samples, in which sample is experienced with 25 times stretching of 30 % deformation in each durability test. The resistance change rate was only varied from 4.5 to 6.5, even after a repeated stretching test up to 300 times, and that corresponds to a slight change of ~14 % in the resistance. Secondly, we have detected the variation of incident light-power on the samples with different concentrations of graphene flakes and graphene quantum dots. To perfomce such experiments, the fabricated samples are illuminated by using the ultraviolet LED with a wavelength of 365 nm. It was found that the measured photocurrent will increase from 300 μA to 410 μA with the increasing of illumination power from 0 to 3600 mW. It corresponds to ~30 % increasment in the measured photocurrent. As a result, we believe such novel hybrid graphene nanostructured sensors will play an important role for the detection of human motions in the near future.