利用電熱效應檢測甲基苯丙胺在電化學感測器上之效率研究

由於某些物質在電極上會有發生電子轉移的化學性質，因此可以將此特性應用在電化學感測器的研究以及設計上。本研究成功利用電熱效應來提升電化學感測器的檢測效率。藉由施加不均勻的交流電場於微流道中的電化學感測器上，因此會在流場內產生一個作用力，稱為電熱力。這個作用力會形成一對攪拌的渦流並對流場以及反應面上的擴散邊界層產生擾動，增加了反應物傳輸到電極表面的量，因此有效地提升反應所產生的峰值電流值。本研究藉由有限元素軟體模擬電化學檢測器上甲基苯丙胺(即冰毒)的電子轉移反應，當溶液處於靜止的情況時，反應為擴散控制。由於反應物電子轉移的速率大於擴散到電極表面的速率，因此會在電極表面形成擴散邊界層，限制反應物傳遞到電極的表面。其中會影響擴散邊界層形成的變數都會在模擬中去討論，包括流道的高度、反應面的位置、角度以及產生電熱效應提供的電壓大小以及電極位置。在嘗試了流道中許多反應面的位置後，可以發現峰值電流會有不同的放大倍率，其中在施加交流電壓峰對峰30 以及工作頻率100 kHz且反應面中心座標位在(750,570)時，峰值電流會有5.19倍的放大。接著嘗試去調整反應面的角度去看結果，發現反應面位置在(750,560)並且逆時針旋轉45度有5.44倍的放大效應。最後將用來產生電熱效應的電極置於流道底部(反應面的兩旁)，可以發現有5.76倍的放大效應。綜觀而論，反應在加入電熱效應以及配合反應面的幾何位置可以有效放大反應的峰值電流，進而達到提升檢測靈敏度的目標。期待能在未來將模擬的結果應用在電化學感測器的設計上面。

關鍵字

循環伏安法；甲基苯丙胺；電熱效應；電化學感測器；有限元素分析

並列摘要

Due to the chemical properties of some of the reactants that undergo electron transfer on the electrode, this property can be used in studying and designing electrochemical sensor. In this study, the electrothermal effect was successfully used to improve the detection efficiency of electrochemical sensors. By applying a non-uniform AC electric field to the micro-channel of the electrochemical sensor, the electro-thermal force can be generated, a pair of stirring vortices can be formed to stir the flow field and the diffusion boundary layer on the reaction surface, and hence increase the transport of the analytes to the reaction surface to enhance the peak current generated by the reaction. In this study, the electron transfer reaction of methamphetamine (MA) on the electrochemical sensor was simulated by finite element software. When the solution is at rest, the reaction is diffusion-controlled. Since the rate of electron transfer of the reactants is greater than the rate of diffusion to the electrode surface, the diffusion boundary layer which would hinder the transport of reactants to the reaction surface. Several crucial factors that affect the formation of the diffusion boundary layer are all discussed in the simulation, including the channel height, the position and angle of the reaction surface, and the magnitude of the voltage provided by the electrothermal effect as well as the electrode position. It is found that by changing the position of the reaction surface the largest enhancement is found at the position (750,570), under the applied AC field 30 peak-to-peak and operating frequency 100 kHz. The peak current can be raised up to 5.19. Then trying to adjust the reaction surface angle to get the results, and it is found that the peak current can be raised up to 5.44 when the position is at (750,560) and counterclockwise rotation of 45 degrees. Finally, it is found that the peak current can be raised up to 5.76 when the position of electrodes which used to generate the electrothermal effect were placed at the bottom of the micro-channel (on both sides of the reaction surface). In conclusion, the peak current of the reaction can effectively amplify by applying the electrothermal effect and adjusting the geometric position of the reaction surface, thereby achieving the goal of improving the detection sensitivity. It is expected that the results of the simulation can be applied to the design of the electrochemical sensor in the future.

並列關鍵字

Cyclic voltammetry ； Methamphetamine ； Electrothermal effect ； Electrochemical sensor ； Finite element analysis

參考文獻

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利用電熱效應檢測甲基苯丙胺在電化學感測器上之效率研究

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