Metodología De Diseño E Implementación De Un Sistema Para Generación De Campos Magnéticos Uniformes Con Bobinas Helmholtz Cuadrada Tri-Axial

Abstract

ResumenSe presenta una metodología de diseño e implementación de un sistema para generación de campos magnéticos uniformes de baja magnitud y frecuencia, sobre un volumen específico utilizando una bobina Helmholtz cuadrada tri-axial. El procedimiento de diseño se basa en conceptos teóricos y simulaciones a partir de expresiones matemáticas simples que relacionan el área, con campo magnético uniforme, con la longitud de las bobinas. Además, se construye el modelo computacional y se simula usando software de elementos finitos. Se observa que los resultados teóricos son consistentes con los resultados del modelo de simulación y las pruebas mediante medición de campo magnético. Se concluye que la metodología de diseño permite establecer un procedimiento simplificado y repetible, para obtener campo magnético uniforme en un volumen de trabajo adecuado para realizar estudios in-vitro o in-vivo. Palabras clave: bobina Helmholtz, campo magnético, elementos finitos, estudios in vitro A Design and Implementation Methodology of a System to Generate Uniform Magnetic Field Volume with Tri-axial Square Helmholtz Coils AbstractThe design and implementation methodology of a system to generate low-magnitude and low-frequency uniform magnetic fields on a specific volume using a tri-axial square Helmholtz coil is presented. The designing procedure is based on theoretical concepts and simulations from simple mathematical expressions that relate the area, with uniform magnetic field, with the length of the coils. Also, the computational model is constructed and simulated using finite element software. It is observed that theoretical results are consistent with simulation model results and the magnetic field measurement tests. It is concluded that the design methodology allows establishing a simplified and repeatable procedure to obtain a uniform magnetic field in the volume of interest suitable for in-vitro or in-vivo studies.

A simple geomagnetic field compensation system for uniform magnetic field applications

“…Taking into account the design parameters (physical and electrical) and operational conditions of the TSH coils system (N=50 turns, electric current for each pair of coils 1.5 A, 1.45 A and 1.4 A from the largest to the smallest respectively), the simulation is performed energizing each pair of coils independently (to obtain B x,y,z =200 µT), generating the contour maps of the magnetic flux density shown in Figure 5. Furthermore, the direction of the magnetic field lines and the uniformity region over the center of separation of the coils are shown [6].…”

“…The TSH coils system [6] consists of an array of three square Helmholtz coils pairs as shown in Figure 1(a), where each pair is located on each coordinate axis (x, y, z). The study of the behavior of the magnetic field B generated by the square Helmholtz coils is made using the Biot-Savart law [22,23 ]for each finite wire as presented in Eq.…”

“…The square coils are connected in series generating a highly uniform magnetic field on the axis of symmetry (z-axis); therefore solving (1) for x = y = 0 the resultant magnetic field is equal to the B z component because the other (B x and B y ) components are zero [23] and it is calculated by the following Eq. (2) (2) In this research, the design of the TSH coils was dimensioned for studies on biological systems in vivo and in vitro; that is, allowing the experimentation with cellular culture plates, small animal or small seeds [6]. The side lengths defined were 0.56 m, 0.58 m and 0.60 m on each symmetry axis x, y and z respectively.…”

“…Helmholtz configuration consists in a pair of coils located parallel on either side of the test area along a common axis (in this case z-axis), spaced at a distance h as shown in Figure 2 [23]; where each black thick line represents a square coil of conductive wire, α is the half side length of the coil, P is the evaluated point and s is the perpendicular distance from the current loop axis ( on x-axis) to P. Each coil consists of N turns and the relationship between the side and the separation distance for square Helmholtz coils is given by a factor of 0.5445 (h=1.089α) [6], these physical parameters depend on the restrictions of the application in terms of the desired volume with a uniform magnetic field. The square coils are connected in series generating a highly uniform magnetic field on the axis of symmetry (z-axis); therefore solving (1) for x = y = 0 the resultant magnetic field is equal to the B z component because the other (B x and B y ) components are zero [23] and it is calculated by the following Eq.…”

“…Many of these studies ideally require devices capable of generating uniform magnetic fields and furthermore guaranteeing a controlled and repeatable exposure to different samples involved in the experiment [4,5]In this sense, the arrangements of aircore coils have been traditionally used for this purpose, particularly circular and square geometries [6][7][8].…”