水溶液原子力顯微術雙模態磁激振裝置之設計與開發

原子力顯微術已經廣泛的應用於分子結構與機械特性的研究。靜態模式與輕敲模式是原子力顯微術最常用的兩種傳統模式。靜態模式容易造成軟性物質的破壞與損毀；輕敲模式利用壓電元件激振微懸臂探針產生共振，此模式可減小對樣品的損壞，然而輕敲模式應用在水溶液環境中時，水溶液的黏滯性會降低微懸臂振動的品質因子並使得共振模態較難激發，而採用壓電元件激振微懸臂的方式，振動不僅從懸臂夾持機構傳遞至懸臂上亦從流體傳遞至懸臂上，進而影響成像品質。輕敲模式又分為彎曲和扭轉模態兩種操作模式，彎曲模式主要量測探針與樣品間的垂直作用力，但在探針掃描時探針會對樣品產生較大的側向作用力而損壞樣品。扭轉模式為量測探針與樣品間的側向作用力，代替垂直輕敲運動，扭轉模式可以快速滑過樣品表面而有較少損壞。扭轉模式被開放用於探討不同表面性質，如摩擦力、黏滯性等。為了提升微懸臂在水溶液環境下的動態特性，採用勞倫茲力的激振方式直接驅動微懸臂，並以理論分析磁力激振下的微懸臂動態特性。設計開發適用於水溶液環境下的磁激振微懸臂載台能激發微懸臂的彎曲及扭轉振動模態。為了區分彎曲及扭轉振動模態，運用磁導引原理開發了一個雙模態切換裝置。透過磁場模擬軟體分析激發行為和磁場條件之間關係以最佳化磁激振裝置。藉由實驗分析驗證磁激振台的雙模態切換的功能，原子力顯微術透過磁激振可以在空氣和水溶液環境下掃描石墨樣品，並且都能掃瞄到0.3 nm的單層石墨台階。

關鍵字

原子力顯微鏡；彎曲模態；扭轉模態；磁力激振；水溶液

並列摘要

Atomic force microscopy (AFM) has been widely used to investigate structures and mechanical properties of materials on surfaces. Static force mode and tapping mode are two most used operation modes. For operating in static force mode, the AFM tip tends to damage or dislodge the soft materials during scanning. For operating in tapping mode, cantilever stimulated by the piezoelectric element can reduce the damage of the sample. However, when the tapping mode is applied in water, the viscosity of water will reduce the quality factor of the vibration, and make more difficult to excite the resonant modes. The tapping mode can be divided into the bending and the torsional mode, and the bending mode is mainly used to measure the vertical force between the tip and the sample. However, the bending mode induces greater lateral forces that can damage sample during scanning motion. The torsion mode is applied to measure the lateral force between the tip and the sample. Instead of vertical tapping motion, the torsion mode can fast skin the sample with less destruction. The torsion mode is developed to investigate diverse surface properties, such as friction, viscosity, etc.. In order to enhance dynamic characteristics of the cantilever in water, Lorentz force method is applied to stimulate cantilever directly, and theoretical analysis dynamic characteristics in magnetic stimulation. The purpose of this thesis is to design and develop the magnetic stimulation device to achieve the bending and the torsion stimulations of the cantilever for AFM in water. For separating the bending and torsion stimulations, a bi-modal switch is developed by using the magnetic conducting principle. By using magnetic simulation software, the relationship between the stimulated behaviors and the switching fields are analyzed in order to optimize the magnetic stimulation device. The experimental tests verify the function of the bi-modal switch in the magnetic stimulation device, and the AFM with the magnetic stimulation device can scan the graphite samples in the air and the water and resolve the 0.3 nm single-layer graphite steps.

並列關鍵字

Atomic force microscopy ； Bending-resonance mode ； Torsion-resonance mode ； Magnetic stimulation ； Liquid

參考文獻

[12] 楊志文, “彎曲式與扭曲式原子力顯微術之研究與應用’’, 國立台灣大學理學院物理研究所博士論文, 2007

[3] Maivald, P., Butt, H.J., Gould, S.A.C., Prater, C.B., Drake, B., Gurley, J.A., Elings, V.B., and Hansma, P.K., “Using Force Modulation to Image Surface Elasticities with the Atomic Force Microscopy”, Nanotechnology, 1991, pp.103-106

[4] Liu,Y., Wu, T., and Fennell, E.D., “Lateral Force Microscopy Study on the Shear Properties of Self-Assembled Monolayers of Dialkylammonium Surfactant on Mica”, Langmuir, Vol. 10, No. 7, 1994, pp.2241-2245

[5] Hartman, U., MAGNETIC FORCE MICROSCOPY, Annual Review of Materials Science, 1999

[6] Binning, G.,Rohrer, H.,Gerber, Ch., and Weibel, E., “Surface Studies by Scanning Tunneling Microscopy”, Review of Scientific Instruments, Vol. 49,No 1, 1982,pp.57

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水溶液原子力顯微術雙模態磁激振裝置之設計與開發

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