Carlos R Pinedo

METODOLOGÍA DE DISEÑO E IMPLEMENTACIÓN DE UN SISTEMA PARA GENERACIÓN DE CAMPOS MAGNÉTICOS UNIFORMES CON BOBINAS HELMHOLTZ CUADRADA TRI-AXIAL

The 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.

Medición de Impedancia Eléctrica en Tejido Biológico – Revisión

This paper presents a review of the electrical properties of biological tissues regarding their study, characterization, and measurement techniques. Electrical conductivity (σ) and permittivity (e) property of tissues, and models developed for their estimation and approximation are mentioned. Measurement elements, advantages and disadvantages of different methods and their applications are presented. Some types of signals used in terms of current and frequency of application are described. Finally, some recommendations to consider for measurements in vivo to reduce errors produced by multiple physiological sources are done. This review permitted to obtain guidelines and conditions for impedance measurement work of femur, which one is doing.

Resultados preliminares del crecimiento de tejido celular usando un bioreactor con sistema de estimulación magnética

This article presents the preliminary results obtained from an earlier publication of a design study performed to integrate a cellular culture bioreactor along with an external magnetic stimulation system, which was aimed at creating ideal environmental conditions that allowed for cellular culture and cellular tissue growth to take place in three dimensions, under a sterile environment favorable for the development of bioorganic grafts which were exposed to controlled electromagnetic fields. Cellular tissue was used from cellular lines of Normal Human Skin Fibroblast (NHSF) and was seeded on bio-synthetic scaffolds synthesized from polylactic acid (PLA) and Chitosan mixtures. The cellular tissue covered scaffold was then introduced into the cellular culture bioreactor, subsequently it was filled with cellular culture medium and put under dynamic flow conditions in while at the same time using the external magnetic stimulation system to irradiate the cellular tissue with controlled magnetic fields. The results present static tests of cell growth where the maximum change in growth was after 48 hours when the cells were exposed to a 1 mT, 60 Hz magnetic field; they proliferated at a rate of 52% without Chitosan, 75% with Chitosan and 53% under dynamic flow versus the non-exposed cellular tissue. These results have allowed us to continue our experimentation techniques to evaluate changes in 3-dimensional growth of magnetically stimulated tissues under dynamic flow.

Growth rates of dynamic dermal model exposed to laminar flow and magnetic fields

Introduction Ongoing research in the use of electromagnetic stimulation as coadjuvant in fracture healing has led the authors to begin generating computer models in order to predict cellular growth changes when cells are electromagnetically stimulated. By generating these models, scientists will be able to better understand how electromagnetic fields affect cellular development. The experimental design integrated a cellular culture bioreactor along with an external magnetic stimulation system, which allowed for dermal models to be exposed to controlled magnetic fields. Methods Initially, it was necessary to analyze the static growth of Normal Human Skin Fibroblast (NHSF) cells when they were exposed to Extremely Low Frequency – Electromagnetic Fields (ELF-EMFs). Using optimal conditions for the NHSF culture, from stimulation signal to scaffolding material, we were able to perform the dynamic flow stimulation experiments. Results The following systems were developed: (1) a bioreactor aimed at cellular tissue culture, and (2) Helmholtz coils capable of generating stimulation signals for the cultured tissue. The authors were able to appreciate the quantified values of cellular density diluted in all the experiment samples that were taken and overall, the irradiated samples displayed an average increase of 53% higher cellular density for the same amount of initial cellular seeding when the cells were exposed to a 1 mT, 60 Hz magnetic field signal. Conclusion ELF-EMF’s indeed alter NHSF cell growth rates and it is the challenge of the authors to continue investigating what cellular mechanisms are altered when cells are exposed to ELF-EMF’s.

Medición de Campos Electromagnéticos en la Ciudad de Cali, Colombia

This paper shows a measurement methodology of the electromagnetic field produced by radio and telecommunications installations and presents results obtained in the evaluation of 50 measurement sites in the city of Cali in Colombia. This work was done because people’s concern about proliferation of radio base stations in urban areas, and their fear about the possible dangerous effects of the electromagnetic fields on human health. The evaluation was carried out to determine and quantify the levels of electromagnetic field that exist in the environment of the city. In general, the values found were lower than 0.5% of the limit established by the International Commission for Non-Ionizing Radiation Protection, ICNIRP (0.2 mW/cm 2 ). However, in two sites the measured values exceeded