Simulation on detecting efficiency of methamphetamine in an electrochemical sensor with applying electrothermal effect

• Main Authors: Jui-Sheng Sung, 宋睿盛
• Other Authors: Sheng-Der Chao
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/y6pb62

碩士 === 國立臺灣大學 === 應用力學研究所 === 106 === 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.