Reimplantable Microdrive for Long-Term Chronic Extracellular Recordings in Freely Moving Rats

Extracellular recordings of electrical activity in freely moving rats are fundamental to understand brain function in health and disease. Such recordings require a small-size, lightweight device that includes movable electrodes (microdrive) to record either a new set of neurons every day or the same set of neurons over time. Ideally, microdrives should be easy to implant, allowing precise and smooth displacement of electrodes. The main caveat of most commercially available microdrives is their relatively short half-life span, in average ranging from weeks to a month. For most experiments, recording days–weeks is sufficient, but when the experiment depends on training animals for several months, it is crucial to develop new approaches. Here, we present a low-cost, reusable, and reimplantable device design as a solution to extend chronic recordings to long-term. This device is composed of a baseplate that is permanently fixed to the rodent’s skull, as well as a reusable and replaceable microdrive that can be attached and detached from the baseplate, allowing its implantation and reimplantation. Reimplanting this microdrive is particularly convenient when no clear neuronal signal is present, or when the signal gradually decays across days. Our microdrive incorporates a mechanism for moving a 16 tungsten-wire bundle within a small (∼15 mm3) lightweight device (∼4 g). We present details of the design, manufacturing, and assembly processes. As a proof of concept, we show that recordings of the nucleus accumbens core (NAcc) in a freely behaving rat are stable over a month. Additionally, during a lever-press task, we found, as expected, that NAc single-unit activity was associated with rewarded lever presses. Furthermore, we also show that NAc shell (NAcSh) responses evoked by freely licking for sucrose, consistent with our previously published results, were conserved from a first implant to a second microdrive reimplant in the same rat, notably showing reimplantation is possible without overtly affecting the functional responses of the area of interest. In sum, here we present a novel microdrive design (low-cost, small size, and light weight) that can be used for long-term chronic recordings and reimplanted in freely behaving rats

PROTOTIPO PARA EL CONTROL ELECTRÓNICO DE UN MOTOR BLDC USADO EN UN VEHÍCULO ELÉCTRICO (PROTOTYPE FOR THE ELECTRONIC CONTROL OF A BLDC MOTOR USED IN AN ELECTRIC VEHICLE)

Resumen En este trabajo, se presenta el desarrollo de la electrónica para el control de un motor BLDC que forma parte de la etapa de tracción de un vehículo eléctrico. La información que se ofrece considera la electrónica de potencia, la instrumentación y el control con base en un microcontrolador de 8 bits. En el documento se da una breve explicación del funcionamiento general del motor y se presenta la estructura general del controlador, en donde se exponen los puntos relevantes de la electrónica de potencia y las consideraciones que se tomaron en cuenta para la elección de sus componentes. Se describe el algoritmo que ajusta el ciclo de trabajo y controla el voltaje promedio que se aplica al motor para evitar condiciones adversas de sobretensión y sobre corriente. Se incluyen los resultados experimentales obtenidos en el laboratorio, así como el desempeño obtenido durante la competencia Sell Eco-Marathon Americas 2019. Palabras Clave: Control electrónico, electrónica de potencia, microcontrolador, motor Brushless, sensor de efecto Hall. Abstract In this work, the control electronics development of an BLDC motor that is part of the traction stage of an electric vehicle is presented. The information offered considers power electronics, instrumentation and the control based on an 8-bit microcontroller. The document gives a brief explanation of the general operation of the electric motor and the general structure of the controller is presented, where the relevant points of the power electronics and the considerations that were considered for the choice of its components are exposed. The algorithm that adjusts the duty cycle and controls the average voltage applied to the motor is described to avoid adverse overvoltage and overcurrent conditions. The experimental results obtained in the laboratory are reported, as well as their performance in the Sell Eco-Marathon Americas 2019 competition. Keywords: Brushless motor, electronic control, Hall effect sensor, microcontroller, power electronics

Definición de metodología para la fabricación de material compuesto a base de polietileno de tereftalato y virutas metálicas

En este artículo se presenta el desarrollo de un material compuesto a base de Polietileno de Tereftalato (PET) y virutas metálicas de acero y aluminio, desde el proceso empleado para la fabricación de placas (probetas), hasta la realización de tomografía computarizada y ensayos de tensión. A pesar de que los resultados de resistencia del material han sido menores respecto a los que presenta un material PET virgen, este estudio ha permitido definir las condiciones del proceso de fabricación de las placas.&nbsp

DESARROLLO DEL PROTOTIPO DE UN WATTHORÍMETRO DIGITAL (DEVELOPMENT OF A DIGITAL WATT-HOUR METER PROTOYPE)

ResumenEn el ámbito de vehículos eléctricos la información que se deriva del consumo energético de la fuente de polarización permite proponer mejoras y conocer los límites de su desempeño. En este documento, se presenta el desarrollo de un watthorímetro que se diseñó para conocer el consumo que demanda un vehículo eléctrico a su batería. Se discute los sensores empleados para medir las variables eléctricas de corriente y voltaje, así como sus etapas de acondicionamiento. El instrumento se apoya en un microcontrolador en donde se realiza la adquisición y el procesamiento de las señales, así como el despliegue de la información a través de una pantalla de cristal líquido. Se explica el algoritmo empleado para el procesamiento y se presenta su código principal. Por último, se describe el procedimiento para la validación del prototipo, en donde se compara contra un instrumento comercial y se presentan los resultados obtenidos. A partir de esta información, se concluyó una mejora clara con respecto al medidor comercial, el cual presentó un error del 1.8% en comparación con el prototipo desarrollado.Palabras Claves: Joulímetro, Medidor de corriente, Medidor de energía, Medidor de voltaje, Watthorímetro. AbstractDuring the design and development processes for electric vehicles, the information from the energy consumption of the polarization source allows proposing improvements and establishing limits on their performance. In this document, the development of a watt-hour meter, that was designed in order to know the consumption that is demanded from the battery in electric vehicles, is presented. The sensors used to measure the electrical variables of current and voltage, as well as their conditioning stages are discussed. The instrument was based on a microcontroller where the data acquisition and the signals processing were performed; the display of the information was carried out by means of a liquid crystal display. The processing algorithm used is explained and its main code is presented. The procedure for the prototype validation is described comparing it against a commercial instrument.Keywords: Current meter, Energy meter, Joulemeter, Voltage meter, Watt-hour meter

Process Chain for the Fabrication of a Custom 3D Barrier for Guided Bone Regeneration

Guided Bone Regeneration (GBR) is a surgical procedure that consists in the use of barrier membranes to cover bone defects caused by trauma, periodontal disease and other pathologies. These barriers allow the proliferation of bone cells, and prevent the invasion of the defect by non-osteogenic cells (connective and epithelium) in patients with a lack of horizontal and/or vertical bone. This process is essential for the successful dental implant placement. Additive manufacturing (AM) is emerging as an important tool for biomedical applications, especially for regenerative medicine and tissue engineering. This paper proposes a process chain for the fabrication of a custom barrier from cone beam computed tomography (CBCT) as Digital Imaging and Communication in Medicine (DICOM) files obtained from a patient with vertical bone resorption of the anterior maxilla.DICOM files have been processed with Invesalius 3.0 to obtain the tridimensional (3D) anatomy of the region of interest. This 3D model was cleaned, fixed, and smoothed. The prototyped model of the patient’s bone defect was further processed in Rhinoceros to offer a 3D architecture for cell growth. To obtain information of the thermal and mechanical properties a finite element method (FEM) was assessed. The prototype obtained was produced with fused deposition modeling (FDM) an additive manufacturing technology

HERRAMIENTAS QUE REFUERZAN LA ENSEÑANZA DEL DISEÑO ELECTRÓNICO (TOOLS THAT STRENGTHEN THE TEACHING OF ELECTRONIC DESIGN)

Resumen En este documento, se habla de algunas herramientas que pueden apoyar las estrategias de enseñanza y que ayudan a reforzar los conocimientos que adquieren los estudiantes de ingeniería en el área de diseño electrónico. Este trabajo se apoya en tres herramientas que consideramos fundamentales: Notas de curso, programas de cómputo y memorias basadas en videos. Estos elementos, son parte de un proyecto que inició a principios de 2019 y aunque no ha concluido, se puso en práctica en la contingencia sanitaria del presente año. Si bien, el proyecto se planteó como un apoyo para algunos cursos curriculares en una carrera de Ingeniería Electrónica, en los resultados se describe el desempeño que se obtuvo por los estudiantes, ante la necesidad de dar uno de estos cursos a distancia, dando lugar a una reflexión sobre la viabilidad y limitaciones de impartir cursos de ingeniería bajo un esquema de educación abierta. Palabras Clave: Diseño electrónico, estrategia de enseñanza, educación a distancia, enseñanza virtual. Abstract In this document, we discuss some tools that can support teaching strategies for electronic design, which can help to reinforce the knowledge that engineering students acquire. This work is supported by three tools that we consider fundamental: Course notes, support computing programs and tutorials based on videos. These elements are part of a project that began in early 2019 and, although it has not been completed, it was put into practice during health contingency of this year. Although the project was proposed as a support for some curricular courses of Electronic Engineering, the results describe the performance obtained by the students because of the necessity of teaching these courses in remotely form, leading to a reflection on the feasibility and limitations of teaching engineering courses under an open education scheme. Keywords: Distance education, electronic design, e-learning, taching strategy

Suborbital Flight: An Affordable and Feasible Option for Mexican Aerospace Development

Suborbital flights are a low-cost option for universities. To perform suborbital missions, it is necessary to design, plan, test, verify, and validate each and every one of the subsystems that integrate the payload without leaving the Earth. In Mexico, some experiments have been carried out since the 1990s to test communication systems in case of disaster and emergency. The Mexican Service Gondola (CSM) from 2015 to date has made suborbital flights in conjunction with the National Polytechnic Institute and the group of Protective Coatings Resistant to Thermal Changes and Cosmic Radiation (CRTCR) to test communication systems and glass-ceramic coatings. Suborbital flights are a great opportunity to explore the national territory and test new communication systems, structures, and materials

Investigacion del processo de corte por chorro de agua (wjc) y sus aplicaciones en micromecanica

Para la manufactura de dispositivos pequeños, también conocida como micromanufactura, se requiere del uso de herramientas de corte, sistemas de posicionamiento y sistemas de medición, proporcionales a lo que se desea maquinar. Utilizando técnicas convencionales de maquinado por arranque de material, se han logrado obtener las características dimensionales, tolerancias y acabado superficial necesarios para este propósito; pero siempre se tiene la limitante asociada al desarrollo de herramientas adecuadas al tamaño y a los materiales que se desean maquinar. Es por ello que en el Grupo de Micromecánica y Mecatrónica (GMM) de CCADET-UNAM decidió investigar el proceso de corte por chorro de agua (WJC) aplicado a la micromanufactura como una alternativa para cubrir la problemática antes mencionada, con lo cual, se podría ampliar la gama de materiales a manufacturar y se evita la necesidad de desarrollar herramientas de corte convencionales