臺灣博碩士論文加值系統

目的：通常短期的微量的電化學反應會導致材料出現無法觀察到的受損，只有在經過長時間的測試才能觀察到。為了要在短時間內觀察到材料的老化現象，本研究嘗試以加速材料老化的方法來達到此目的。
方法：本實驗利用金、鉑、鈦、鉭四種金屬做為電極的材料，並且利用PBS溶液模擬視網膜的環境。在37℃、50℃、80℃三種溫度下，分別給各電極材料電流，振幅及通電時間分別為±100μA，31μs、±75μA，62μs、±50μA，125μs、±25μA，250μs，頻率皆為1kHz。電極片通電時間24天後測量電極片的表面粗糙度；金屬線材電極分別經過7天與63天後利用ICP測量PBS溶液中金屬的濃度；金屬線材電極經過63天後拍攝SEM。依據阿瑞尼斯方程式(Arrhenius equation)指出溫度影響化學反應速率的方程式，用來進行材料老化的預測。
結果：利用ICP測量PBS溶液中金屬離子的濃度，得到的值接近或低於最低極限值，可以推測使用雙向刺激電流可以減少金屬離子殘留在生物體內的含量。利用測量電極表面粗糙度，可以進一步計算出在80℃時Au的加速老化時間可達到43倍；Pt的加速老化時間可達到16倍；Ti的加速老化時間可達到26倍；Ta的加速老化時間可達到29倍。
結論：本實驗利用溫度可以加快化學反應的特性，想要建立出溫度對電極使用壽命的情形。本實驗的時間長度及使用的材料與溫度與檢驗的方式可能並無法建立一個完全的電極老化模型，但嘗試這個方式的結果，也可粗略的得到不同金屬在相似的環境下，其相對老化速率的比較，可以作為電極選擇的參考。

Objective：It is difficulty to observe the damage occurred in a material for a short term mild electrochemical reaction, however, it can be observed through a prolong test. In order to observe the aging phenomenon in a material in a relative short time, we try to speed up the aging process in chosen materials.
Method：Four kinds of metal, gold, platinum, titanium, and tantalum employed for electrode materials were chosen in this study. PSB solution was used as a medium for simulating the environment in retina. For each material, the conduction currents with magnitude and conducting time through the materials are designed as ± 100μA ,31μs; ± 75μA, 62μs; ± 50μA, 125μs; ± 25μA, 250μs, with frequency of 1kHz that under environmental temperatures of 37, 58 and 80℃ respectively. Surface roughness and metal concentration in PBS solution were measured by surface contour instrument(KLA-Tencor αstep-500), and inductively coupled plasma optical emission spectrometer(ICP-OES Varian 700ES) at 24th day, and 7th and 63th day respectively after starting the simulation. Estimation for material aging extent will be calculated according to Arrhenius equation which is an equation of temperature dependent chemical reaction.
Result：Results of the remaining metal ion in PBS solution are undetectable or below the detecting limitation of ICP, indicating that biphasic current stimulation is applicable while used for exciting neurons. For surface roughness measurements, it is estimated that the aging acceleration rate can be up to 43, 16, 26, and 29 folds for Au, Pt, Ti, and Ta respectively at 80℃ while compared to at 37℃ in 24 days.
Conclusion：Increasing temperature can speed up chemical reaction rate. It can be used to build electrode aging process model in this study. Although it may not be able to build a complete aging process model for an electrode in this study due to finite experimental time, materials being used, temperature settings and measuring methods, however, the results still can give references for further selecting electrode material according to the relative aging process rates under the same environment of the tests.

中文摘要 Ⅰ
ABSTRACT Ⅱ
目錄 Ⅲ
圖表目錄 VI
第一章 緒論 1
1-1研究動機 1
1-2研究目的 1
1-3眼球構造 1
1-3-1 眼球 1
1-3-2 視網膜 2
1-4人工視網膜 4
1-4-1上視網膜刺激電極 4
1-4-2下視網膜刺激電極 5
1-5適用人工電子眼的疾病 7
1-5-1色素性視網膜炎 7
1-5-2老年性黃斑部病變 7
第二章 原理及相關研究 9
2-1彈性疲乏現象 9
2-2電極的老化現象 10
2-3如何加快老化現象 10
2-3-1 溫度對反應速率的影響 10
2-3-2 電化學反應動力學 11
2-4阿瑞尼斯方程式ARRHENIUS EQUATIO 13
2-4-1 應用阿瑞尼斯方程式 13
2-4-2 Arrhenius equation 13
第三章 實驗架構及方法 16
3-1電極材料與製備電極 16
3-1-1電極材料 16
3-1-2製備電極 17
3-2保溫箱及溫度記錄 18
3-2-1溫控電路 18
3-2-2 8051與PC通訊電路 20
3-2-3 PC端利用Visual Basic6.0 記錄溫度 21
3-3可控式電壓控制電流源電路 23
3-3-1雙向刺激電流 23
3-3-2電壓控制電流源電路 24
3-3-3可控式電壓控制電流源電路 25
3-4表面粗糙度(RA) 27
3-4-1 Ra的定義 27
3-4-2表面輪廓儀(alpha-step) 28
3-5感應耦合電漿發射光譜儀(ICP-OES) 28
第四章 結果 30
4-1溫度控制 30
4-2刺激電流波形圖 31
4-3 電流源穩定性 33
4-4 測量RA的結果 34
4-5 ICP-OES的結果 40
4-6 預測加速老化所需的時間 41
4-7 金屬線材的SEM 43
4-7-1 Au的SEM 43
4-7-2 Pt的SEM 47
4-7-3 Ti的SEM 50
4-7-4 Ta的SEM 54
第五章 討論 58
5-1電刺激的頻率 58
5-2 材料 58
5-3電化學 58
5-4加速實驗的限制條件 59
5-5為何電化學的結果不理想 59
5-5-1測量Ra值所造成的原因 59
5-5-2電極的來源 60
5-5-3可改善的方式 61
第六章 結論 62
參考文獻 63

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