Electric Field Simulation - Essay Example

? Electric Field Simulation This paper uses COMSOL Multiphysics to simulate an electric field between three electrodes so as to analyze andcalculate the electric potential in middle of the three electrode arrays. Also, this paper will measure the proportion of field strength distribution between all the electrode arrays. In addition, a calculation will be made based on certain conditions: the first is that oil has relative permittivity of 200?m and the second is water of 20?m. The electrodes are 5 ?m thick and the water extends about 100 ?m below and above the three electrodes. Through COMSOL Multiphysics we discovered the results after simulating an electric field by using 2D and 3D of the electrostatic module. These modules provided many kinds of movement in the electric field for the three electrodes, which were energised with +1V, 0V, and -1V electrical voltages. Also, the strong and weak points are posted between the three electrodes and show the electric potential of the field. Finally, this paper will show the form of the distribution of electric potential and electric field between the three electrodes for the above mentioned conditions. Introduction: After Michael Faraday discovered the electric field, he developed electricity into something practical that could be used in many technologies, especially microsystem devices. According to James Clear Maxwell, “the portion of space in the neighborhood of electrified bodies” is called an electric field [1]. At present, there are several applications used that are related to microtechnology and are beneficial to our lives. A good application in medicine is biology cells within medical laboratories. In this way, application is applied to the electric field to move cells and separate or analyze cells via impact electric forces. The movement, separation, and analyzing is done through a technique known as AC electrokinetics. This technique occurs when an electric field interacts with dipoles, but it depends on forces between repulsion and rotation by altering the nature of the dynamic field [2]. This new technique is beneficial in biotechnology because of the electric field [3]. Also, the AC electrokinetics technique depends on a delicate process known as dielectrophoresis. This is “the migration of uncharged particles towards the position of maximum field strength in a non-uniform electric field” [4]. The basic principle operation of dielectrophoresis is by deference of electromagnetic and dielectric properties. For example, the separation of cancer cells is behind the electrodes, while the natural cells move away from the electrodes due to variations of the electric field [5]. Figure 1 shows the forces of attraction and repulsion between cancer cells and normal cells. Fig.1. Basic Principle of Dielectrophoresis An electric field is a region around a charged particle or object within which a force would be exerted on other charged particles or objects. It is defined as an area between two charges and then there is a force (positive or negative) exerted [6]. The forces exerted on the test charge will be directly proportional to another charge according to Coulomb’s law [7]: Fe ? q1 q2 If divide the forces on the test charge: E=Fe /q ' Where E = electric field (N/C) and F = force (N) and q' = charge on test charge (C) Also, according to Coulomb’s law, we can find E where: = the permittivity of free space Then we can calculate the electric flux by using Gausses’ law [8]: Q = ? E.d There is a relationship between the electric field and electric potential if the electric potential is identified in an action area, then we can calculate the value of the electric field by: dV = - E.d. However, the electric potential consists of lines called equipotential lines. There is a direct correlation between the electric field lines and the energy of electric potential because the first one always puts the electric potential of direction that causes dropping electric potential [9], whereas, in this case, we are dealing with an accelerometer that has three microelectrodes and comb-shaped structure. The accelerometer depends on the displacement charge that is used to extract biological cells to move and separate it for analysis. This system, using the AC electrokinetic process, is called dielectrophoresis. The three microelectrodes are energized with +1V, 0V, and 1V electrical volts, and the inner electrode area is full of oil that exhibits a relative permittivity of 200?m (Figure 3). COMSOL Multiphysics originated from Sweden. It is a simulation environment that simplifies all the steps in the modeling process: defining geometry, meshing, specifying physics, solving, and then imagining results. It is also useful as a platform for the application explicit modules. COMSOL Multiphasics is beneficial because of cheaper cost and easy-of-use to solve and analyse any problem. Figure 3 Through the COMSOL Multiphysics program we will simulate the three microelectrodes in two different situations. For the first task, we will calculate the electric potential between the three microelectrodes and electric field distribution between arrays with oil that exhibits a relative permittivity of 200?m. In addition, for the second task we will calculate the electric potential and electric field distribution but with different conditions: 5?m thickness and water that extends 100?m above and below the microelectrodes. Methodology (modelling): First of all, to simulate the three microelectrodes with COMSOL Mulitphysics we must select a space dimension in order to add two dimensions. Then we will choose Electrocstatics from the nodules physics. After that, for study type we choose stationary through using the table from the polygon that we found in Geometry. These modules have specific parameters with a width of 80 µm and a height of 120 µm. Figures 4A, 4B, and 4C show the building structures in the order. Following that, we field all of them in a shape figure. Figure 4A: Show the First Part of the Microelectrodes Figure 4B: Show the First and Second Part of the Microelectrodes Figure 4C: Show the Full Structure of the Microelectrodes Figure 4D: Show the Microelectrodes in the Chip In order to simulate the micro device used to extract the biological cells in Figure 3, we need to take a sample using the AC electrokinetic process known as dielectrophoresis. There are three microelectrodes that are illustrated in green, red, and blue and are energized with +1V, 0V, and -1V electrical volts respectively. The inter-electrode region (white) in Figure 4F is filled with oil that exhibits a relative permittivity of 200?m. Figure 4F: Shows Three Microelectrodes Filled with Oil To begin with, we must calculate the electric potential and electric field strength distribution between the microelectrodes arrays we applied with COMSOL Multiphysics in the module shown in Figure 4F. Then, we must engineer the three microelectrodes (+1V, 0V, and -1V) to add an interface identifier from the electric potential in the electrostatics section. After that, we press compute to get the final simulation and results shown in 2D (Figure 5). Also, we show the equation that assumes adding electricstatics with charge conservation that shows us the equation using the above module: In this case, the electric potential, V, is defined by the relationship: E =-?V D = ?0E + P Through joining this equation with the constitutive relationship between the electric displacement D and the electric field E, it is likely to represent Gauss’ law, as shown in the next equation: This equation describes the electrostatic field in dielectric materials. For in-plane 2D modeling, the Electrostatics interface assumes a symmetry where the electric potential varies only in the x and y directions and is constant in the z direction. This implies that the electric field, E, is tangential to the xy-plane. With this symmetry, the same equation is solved as in the 3D case. Where: is the relative permittivity of water equal to 200, E is the electric field, and ? is the space charge density. This equation describes the electrostatic field in dielectric materials. On the other hand, we used COMSOL Multiphysics to simulate the above module parameters but with different data conditions. This is to calculate the electric potential and electric field. The new conditions are 5 µm chip thickness and the water extends 100µm above and below the three microelectrodes (blue areas) in Figure 5. The materials of microelectrodes consist of silicon (potion) and have 10 relative permittivity green areas shown in Figure 6. In this module we are dealing with +1V, 0V, and -1V electric voltages. Then we right click on the electricstatics section to add electric potential and energize the three microelectrodes by electrical voltages. This deals with the top one, which is energised with -1 volt; the middle one is energised with 0 volt; and the bottom one with +1 volt (Figure 7). After this we are going to compute the module to get the final result. Figure 5: Shows 3D Layout of the Three Microelectrodes with 5µm thickness and the Water Extending 100µm Above and Below Figure 6: Shows Microelectrodes with Different Voltages and Water Above and Bottom of Microelectrodes Result and discussion: First, we will discuss of results from the 2D simulation of electrode field between the three microelectrodes that are shown in Figure 7. We can see that the area that is strong with electric potential from 0.7V to 1V is shown by the red color in Figure 7. On the other hand, the area between -0.6V and -1V is the weak areas of electric potential and is referred to by the blue color in Figure 7. For the area between the strong and weak points, between -0.6V and 0.7V, the electric field can alternate. Therefore, the electric potential is directly proportional with value of electrical voltage, as can be seen in Figure 7. The strength of electric potential is in the microelectrodes that have the highest electrical voltage and, in the opposite way, the weak region has the lowest electrical voltage. Figure 9: Shows the Electric Potential in Strong and Weak Areas Figure 7: shown electric potential with 2D Figure 8: shown the arrow surface of electric displacement field Electric field lines always extend from a positively charged object to a negatively charged object, from a positively charged object to infinity, or from infinity to a negatively charged object. This is clear from Figure 9. Also, we can see that by using contours from the electric potential section, the electric lines become stronger if the distance between them is short. In the opposite way a distance between two electric field lines that are long, then the electric lines become weak. Distribution depends on the distance between lines. In addition, the densities of the electric field lines always stay close to the greatest charge shown in Figure 9. Figure 10: Shows the Concentration of the Electric Field By the surface distribution section, we can present the quantity of the concentration of the electric field, particularly on the corner heads of polarity. We can see this in Figure 10. The high point of electric field began at 0.7V and went to 1V. This was referred by the red colour. The static point of the electric field was 0V (yellow colour). Whereas, the area between -0.5 V and -1V was the weakest area in the electric filed. In that area, the electric field can fluctuate from -2.5V to 2.5V. Figure 10: Shows the Strong and Weak Points of the Electric Field We find from the next section that if we cut a part from the microelectrodes, which can be between the corner of the microelectrodes, it illustrates to us an accurate depiction of the electric field. It is clear from Figure 10 that the weak point of electric field is from 0.5V to 0V. But, we can see that the strong point of electric field is between 1.9V and 2.5V. Also, 1.3V is the fixed point of electric field. The level of volatility in this case is between 0.7V and 1.2V. As for the three dimensional electrostatic model shown in Figure 11, we will get the result to calculate the electric potential and electric field distribution for 20µm above the three microelectrodes arrays, which are 5µm thick and have water that extends 100µm above and below the electrode arrays. In addition, we can see the concentration electric field is located between polarity (shown in Figure 14) and the strength point was between 3 and 5.0607, while the weak point was from 0.5 to -2.2821. It is clear from Figure 12 that it illustrates the direction of the electric field between the three microelectrodes as electrical voltages (1V, 0V, and -1V). However, if we consider the electric potential lines in Figure 13, we can see the strong points from 0.6818V to 0.9545V (red region). Also, the weak points are between -0.5909V and -0.9545V. The fixed point is at 0.15V, which means that the directions electric filed are evade from high electrical voltages to low electrical voltages. These electric field lines are called lines of force because it is the cause of the electric field. Figure 12: Shows the Distribution Volume of the Electric Field Figure 11: Shows the 3D simulation with the Microelectrodes (5µm) and the water extending 100µm above and below Figure 13: Clarifies the Electric Potential Lines Figure 14: Shows the Electric Field Concentration Between Arrays Conclusion: In conclusion, this report provides us the simulation of the electric field by COMSOL Multiphysics and was fabricated between three microelectrodes in two different conditions that were used to extract biological cells to be moved, separated, or analyzed. The basic principle operation of the AC electrickinetic process, known as dielectrophoresis is used to calculate the electric potential and electric field strength distribution between the Electrode arrays and calculates the electric potential and electric field distribution 20µm above the electrodes arrays. The electrodes are 5µm thick and the water extends 100µm above and below the electrodes, so we will build three electrodes (energized with +1V, 0V, and -1V electrical voltages respectively). The microelectrodes’ corners have a concentration of electric field particularly in the corner near the electric field on a non-uniform location that depends on the electrical voltages of the electrodes. Also, the strength point for electric field and electric potential might be close to electrodes, which have a high value of electrical voltage. However, the weak points are far from the electrodes that have high voltage. Finally, this technique should be useful for movement, separation, and analysis of cancer cells. [1]- Fleisch,D,2011. A Student's Guide to Vectors and Tensor. Cambridge: Cambridge University Press [2]- Hughes M,2000. AC electrokinetics: applications for nanotechnology,IOP science, [online]Available at:< http://iopscience.iop.org/0957-4484/11/2/314/pdf/0957-4484_11_2_314.pdf >[Accessed on 30/10/2012] [3] – Walti C , et al ,2007. AC electrokinetic manipulation of DNA,Journal of Physics D:Applied Physics, [online]Availableat: [Accessed on 30/10/2012] [4]- Oxford Dictionaries ,2012.Oxford University press. [online]Available at: [Accessed on 30/10/2012] [5]- Heydarlou M,2011. Design and Simulation of a Novel Dielectrophoresis based Device to Separate Breast Normal and Cancerous Cells. Singapore: International Conference on Nanotechnology and Biosensors, [online]Available at:< http://www.ipcbee.com/vol25/1-ICNB2011_Q00003.pdf> [Accessed on 30/10/2012] [6] Parks J,2012. Electric Fields Experiment-The Cenco Overbeck Apparatus. The University of Tennessee. Knoxville, Tennessee, [online]Available at:< http://www.phys.utk.edu/labs/Cenco%20Overbeck%20UT%20ElectricFields.pdf>[Accessed on 31/10/2012] [7]- Studyphysic,2005. studyphysics.ca, , [online]Available at:< http://www.studyphysics.ca/30/fields.pdf> [Accessed on 31/10/2012] [8]-Physics, , [online]Available at:< http://www.physics.wisc.edu/undergrads/courses/spring10/202/lect3_handout.pdf> [Accessed on 31/10/2012] [9]-physics, online]Available at< http://203.158.100.140/physics/charud/scibook/physics-for-scientists-and-engineers-serway-beichner-4/25%20-%20Electric%20Potential.pdf>[Accessed on 31/10/2012] Read More