TFM: Design of a Communication System Through the Body
Posted on by rookie

The loss of a limb is a traumatic event for a human being, permanently altering the way they perform everyday tasks. Currently, most of these patients require a prosthesis for both aesthetic and functional reasons. Today, there are various types of prostheses, with robotic arms being the most commonly used for movement. These mechanical and/or electrical devices mimic human movements, controlled by the person. At present, the communication between the robotic arm and the user is established either through implants inside the body or via vulnerable communication methods.

The objective of this master’s thesis is to design a non-invasive communication system that uses the human body as a transmission medium. This approach is based on the innovative Human Body Communication (HBC) technology, which is part of Wireless Body Area Networks (WBAN). It is designed for wearable devices on the surface or inside the human body, specifically in the field of medicine. The goal is to transmit electrical or electromagnetic signals using the conductive properties of the human body.

To achieve this, an exhaustive study was conducted to understand how the human body behaves when a signal is transmitted at the selected frequency of 2.45 GHz. The signal will be transmitted through the patient’s forearm, which consists of multiple layers of materials with different dielectric properties. Therefore, computational simulations are necessary to analyze how the signal behaves.

This project is based on two experimental studies aimed at measuring propagation losses. The goal is to place the transmission and reception devices on the skin’s surface, using study [1] as a reference to calculate the signal losses through the multiple layers of the spleen. Additionally, the signal losses associated with transmission through the interior of the forearm, between the transmitter and receiver, were evaluated based on the data from study [2].

Once the system requirements were established, preliminary tests were conducted to validate the designed system. The results showed greater propagation losses than the theoretical estimates, prompting the project to focus on developing a functional prototype that is small, low-cost, and energy-efficient. The following image shows the completed system.

Finally, after testing the assembled system, it was determined that the selected insulator, RFSW-S-125-FR-PSA from Laird Technologies, is effective for communication through the air. However, aluminum yielded better results for communication through the body. On the other hand, the selected antenna was not ideal due to market limitations.

The results obtained suggest multiple areas for improvement and encourage further research to optimize the system.

References:

[1] Y. M. G. M. D. Zhi Ying Chen, «Propagation characteristics of electromagnetic wave on multiple tissue interfaces in wireless deep implant communication,» IET Microwaves, Antennas & Propagation, vol. 12, nº 13, pp. 2034-2040, 2018.

[2] C. G.-P. A. F.-L. A. V.-L. G. V. J. S. M. I. I. B. S. M. I. a. N. C. S. M. I. Ra´ul Ch´avez-Santiago, «Experimental Path Loss Models for In-Body Communications Within 2.36–2.5 GHz,» IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS, vol. 19, nº 3, pp. 930-937, 2015.

TFM: Design and implementation of a simulation environment for transcranial magnetic stimulation in human and mouse brains.
Posted on by rookie

The study of the human brain is currently a fundamental area of interest in science due to the complexity and diversity of functions performed by this organ. Although the brains of humans and mice differ in size and structure, they share numerous fundamental principles that allow scientists to extrapolate findings from rodent studies to humans. However, neuroscience research faces significant challenges due to the intrinsic complexity of nervous systems and the ethical and practical limitations associated with direct experiments on living organisms.

In this context, simulation environments have emerged as powerful tools for research. These environments allow for the modelling and detailed analysis of neural processes in a controlled setting without involving any living organisms. The ability to simulate brain activity when stimulated by external factors not only facilitates understanding of the brain’s response to these stimuli but also can accelerate the development of treatments for neurological diseases, such as cancer or stroke.

The main objective of this work is to develop a simulator capable of stimulating human and mouse brains using the transcranial magnetic stimulation method and quantifying the impact of various parameters in the simulation.

To achieve this objective, various brain simulators currently in use have been analysed, and one has been selected as the basis for the simulator. Additionally, the functioning of transcranial magnetic stimulation and the necessary instruments for carrying out this stimulation method have been studied. Furthermore, the modelling of the magnetic field generated by coils, both with and without a core, has been explored.

After gathering all this information, the simulator was completed, capable of simulating both human and mouse brains. Moreover, it allows for generating stimuli in the target brain with fully customized coils, as it is possible to model them by varying parameters such as height, radius, or number of turns. The intensity circulating through these coils can also be adjusted. Additionally, various commercial coils and stimulation systems consisting of multiple coils were successfully modelled.

Finally, various tests were conducted to verify that the modelling of the different coils was accurate and to measure different parameters. The parameters measured included the maximum radial electric field generated in the brain for each coil, the value of this electric field at different depths, the effect of the distance between the skull and the coil on the stimulation, and the field generated by the stimulation systems. Subsequently, all these tests were parametrized.

This project has developed and implemented a simulator capable of replicating brain stimulation in humans and mice through transcranial magnetic stimulation. The simulator allows customization of parameters such as coil position and number, distance from the skull, or stimulation intensity. After various tests, its accuracy has been confirmed, helping to reduce risks and improve personalized TMS treatments. Additionally, the inclusion of mouse models reduces the need for live experiments. The simulator offers applications in neuroscience research, therapy optimization, and the development of new clinical protocols.

Therefore, it can be confirmed that the proposed general objectives have been achieved and the technical feasibility of the project has been demonstrated.

All the code corresponding to the simulator is located in the following repository: https://github.com/rfparra/TFM

TFM: DISEÑO DE UN SISTEMA DE MONITORIZACIÓN DE CONSTANTES VITALES DE ROEDORES A DISTANCIA
Posted on by rookie

The VISNE project, from the B105 Electronic Systems Lab at the ETSIT in collaboration with the Neuro-Computing and Neuro-Robotics group at the Complutense University, focuses on the development of a thalamic prosthesis to restore vision in humans. In its initial phases, this system will be tested on rodents, specifically mice, through behavioral tests in an operant conditioning chamber, also known as a Skinner box (as can be seen in the image below) .

However, the use of animals for medical research is one of the most controversial and debated topics in the modern scientific community. Therefore, ensuring the welfare of the animals has become a fundamental task, and to this end, the aim is to remotely monitor their vital signs.

In this master’s thesis, two techniques for monitoring mice were evaluated and tested: an infrared camera (MLX90640 from Melexis) for temperature measurement and an FMCW radar (AWR6843AOP from Texas Instruments) for tracking heart rate and respiration through thoracic variations. An electronic system was designed and implemented, consisting of two components: a proof-of-concept using both sensors and a prototype PCB that integrates the temperature monitoring system.

The proof of concept was integrated with a central interface within a Skinner box for mice. A user-friendly graphical interface was developed to display measurements from both sensors over time. A program was created using the infrared camera to detect the rodent’s warm body, positioning it at the central point to enable precise tracking and presence detection. The motion data collected could be used to estimate the rodent’s stress level during behavioral tests. Additionally, this program records temperature and movement data in text files for further analysis.

System tests demonstrated that the camera enabled continuous monitoring of the mouse’s body temperature, while the radar successfully measured heart rate in humans, with results closely aligning with those obtained through traditional methods. However, the radar measurements exhibited notable variability. Additionally, the system effectively measured the respiratory cycle and accurately detected presence.

The Printed Circuit Board (PCB) for the prototype temperature monitoring system was designed and manufactured with compact dimensions of 50 x 103 mm. It includes wireless connectivity and supports data storage on a microSD card. Additionally, the PCB is equipped with a micro-USB port for easy programming and powering of the system. All the TFM’s files are available in this repository: https://bitbucket.org/b105upm/tfm_rpeon/

The PCB has been successfully soldered, tested, and programmed. The embedded software enables data communication with a central node using the MQTT protocol, while the central server capture the data and displays thermal images on a web interface. All the embedded software of this system is located in this repository: https://bitbucket.org/b105upm/skinnerbox

TFG: Design of a localization system based on 5G communications
Posted on by araujo

The arrival of 5G New Radio (NR) networks has improved mobile telephony service conditions. These improvements have made it possible to enhance other uses of these networks, such as localization. The higher bandwidths and directivity of 5G communications allow measurements taken from base stations to be more accurate, resulting in better position estimates than in previous generations of cellular networks. This makes localization applications based on cellular networks gain relevance. In addition, they are more efficient in terms of energy consumption, which is an advantage over GNSS systems.
The objective of this Graduate Thesis is to analyze and implement a localization algorithm based on 5G networks. This algorithm works outdoors and calculates the position locally, so the equipment to be located uses the measurements received from the base stations without interacting with any other element of the network. Certain accuracy and execution time requirements have been established.
To accomplish the objective, a study of the outdoor localization methods based on cellular networks has been carried out in order to select the most accurate one among those reviewed.
Subsequently, the corresponding algorithm has been implemented in a microcontroller, to finally test its performance in different simulated scenarios.
At the hardware level, the STM32 NUCLEO-F767ZI microcontroller has been used.


At the software level, the STM32CubeIDE development environment and C programming language have been used. Since it has not been possible to experimentally obtain the measurements required for the algorithm to work, some Matlab scripts have been created to simulate both these measurements and the test scenarios.
After testing its performance in different scenarios, it can be concluded that the implemented algorithm meets the objectives set, both in terms of accuracy and time, and that it could therefore be interesting to carry out tests in a real scenario.

TFG: Design and Implementation of an NBIoT Communication System
Posted on by Alejandro Guaita

The development of IoT product has generated multiple needs in the field of information and communication technologies. Among them, the challenge of creating technological products capable of functioning independently of the power grid arises, leading to a line of development in telecommunications that, instead of maximizing the transmission capabilities of a system, seeks to minimize its power consumption.

ESTAR project

This TFG is developed within the ESTAR project, an autonomous IoT product meant for monitoring multiple environments. More specifically, it focuses on ESTAR_COMMS, the module which will be in charge of connecting the device to an external server.

In order to provide wireless communications with the lowest energy cost, an analysis of different components is given, concluding with the SARA-R510S-01B. The SARA has access to NBIoT radio technology from the LPWANs that allows for low speed, low payload, sporadic and Ultra-Low-Power transmissions.

In the thesis, the following results are presented:

  • A functional communication design and PCB prototype that uses the SARA-R510S-01B module, with an analysis of all design stages.
  • A first approach to the software design, in addition to a summary of the main AT commands that will be used to control the SARA.
  • The first energy consumption tests with the KeysightB2901A.