Design and Implementation of a Device for Capturing Biological Signals Applied to the Treatment of Ischemic Stroke.
Posted on by rookie
Ikki PCB design

Introduction

This work is part of the STRIKE project, a multidisciplinary initiative aimed at developing new therapeutic strategies for the treatment of ischemic stroke, one of the leading causes of death and disability in Spain and worldwide. STRIKE integrates three techniques: transcranial magnetic stimulation (TMS), implantation of mesenchymal stem cells encapsulated in silk fibroin, and electrical stimulation of the auricular branch of the vagus nerve (aVNS).

In this context, the Ikki device has been designed and implemented a portable system for acquiring biological signals, specifically electrocardiogram (ECG) in rodents and electroencephalogram (EEG) in humans. This work primarily focuses on the electrical stimulation of the auricular branch of the vagus nerve, although it is partially related to transcranial magnetic stimulation. The main goal is to enable real-time monitoring of physiological responses to the applied therapies, thereby facilitating personalized treatment and experimental validation of the proposed techniques. The device has been validated in a real-world setting through human trials.

Keywords

Electrocardiogram, electroencephalogram, biological signals, electrophysiology, biomedical
device, portable, low power consumption, vagus nerve, ischemic stroke, treatment, embedded
system.

The problem

Clinical Context

Ischemic stroke accounts for more than 80% of stroke cases. Conventional treatment is based on early reperfusion and physical rehabilitation, but neurological recovery remains limited. Therefore, new strategies are needed to complement current treatments and improve neuroprotection and brain regeneration. The STRIKE project was born from the development of these new strategies.

Technological Need

To experimentally validate the techniques proposed in the STRIKE project, it is essential to have a device capable of accurately acquiring physiological signals in a portable, non-invasive, and user-friendly manner for researchers. ECG and EEG signals allow for the evaluation of the impact of therapies on the nervous and cardiovascular systems and are fundamental for establishing a personalized treatment approach.

CTB ADC and stimulator

Acquisition system for ECG and stimulation used in the CTB.

Currently, experiments conducted at the Center for Biomedical Technology (CTB) use very large devices that hinder researchers due to their size. Therefore, the long-term goal is to develop a device with a “closed-loop approach.” To achieve this, the signal acquisition device is developed first, and later stimulation will be integrated into the same device.

Proposed Solution

The Ikki device has been developed as a comprehensive solution for acquiring and transmitting biological signals in the context of ischemic stroke treatment. Its design meets criteria of portability, low energy consumption, data capture precision, and ease of use in experimental and clinical environments. The system has been divided into hardware and software components.

Hardware Development (HW)

Ikki PCB design
Ikki V1.3

The complete hardware system has been built around a custom board integrating the following modules:

  • MSP430FG479 Microcontroller: Responsible for acquiring signals from the acquisition circuits. It includes built-in SD16-type ADCs. This is the main microcontroller of the entire system.
  • Signal Acquisition Circuits: Composed of several modules that allow analog processing of the signals to be captured, with filtering and amplification adapted to each signal type.
  • Power Supply System: Composed of a PMIC, a linear regulator, and an inverter that enable symmetrical power supply to the entire system.
  • Communications: Includes test points that allow data collection through the main microcontroller.
  • Connectors and Electrodes: Adapted for use in humans and rodents, ensuring secure and stable connections during acquisition.

The design has gone through several iterations, from initial prototypes to the final version Ikki V1.3, optimized for real-world testing. The quality of the acquired signals has been validated through comparisons with commercial systems.

Software Development(SW)

The software is divided into four layers:

  1. Acquisition Layer:
    • Developed in C using Code Composer Studio.
    • Programs the main microcontroller MSP430FG479.
    • Acquires data via the microcontroller’s built-in ADCs, processed through the acquisition circuits.
    • These data are then sent in a predefined format via SPI or UART to the bridge layer.
  2. Communication layer:
    • Defines a state machine to differentiate data acquired from various channels by the main microcontroller.
  3. Bridge layer:
    • Programs an ESP32 using ArduinoIDE.
    • Receives data from the acquisition layer via SPI/UART and forwards them via BLE.
    • Enables wireless functionality of the device.
  4. Visualization layer:
    • Programmed in Python.
    • Establishes a connection with the bridge layer and displays the data received via BLE on a device screen, such as a laptop.

TFM: Development of an electronic system on smart garments to aid in the diagnosis of neurodegenerative diseases
Posted on by María Tejedor

TFM: Development of an electronic system on smart garments to aid in the diagnosis of neurodegenerative diseases

Parkinson’s disease is a neurodegenerative disorder that affects the nervous system, which mainly causes motor disorders. It affects more than 160,000 people in Spain. In addition, it is expected that due to the growing aging of the population it will become the most common serious disease by the year 2040.
One of the main problems faced in this disease is the delay in its diagnosis. In addition, it is important to ensure that patients’ symptoms are properly monitored in order to correctly adjust their medication.
Over the past few years, the use of wearable devices to monitor patients outside of the hospital environment has increased. Among these devices, those that use sensorized clothing, so that the sensors are integrated into the tissues, are gaining popularity and have great potential. Although these are still at an early stage of development.

In this context begins this Master’s Thesis, which is part of the research line of the B105 Electronic Systems Lab for the development of wearable devices. The main objective of the project is to design and implement an electronic system to control a set of intelligent clothes for the monitoring of different parameters, which can be connected to other wearable devices in the future.

For this purpose, a study of the symptoms of Parkinson’s disease and how it is possible to monitor them have been carried out. We have also analysed which studies have been conducted in recent years using textile sensor to diagnose or monitor this pathology. Subsequently, it has been searched which intelligent garments are being commercialized in the market. And finally, it has been established which requirements are intended to be fulfilled by the design that is going to be carried out.

Due to the initial work done, the design of the system to be implemented has been carried out.

It consists of a pair of socks and a harness, which communicate through Bluetooth with a mobile phone application.

The socks incorporate 3 textile resistors in the sole of the foot, and an IMU in the ankle to monitor the patient’s gait. While the harness makes use of 3 textile electrodes, whose outputs are filtered by a circuit to obtain the ECG. It also incorporates an IMU in the central part of the chest, to monitor the user’s posture. In addition, both garments make use of a PCB in which they operate the control part and the power supply.

In the software development of the project, FreeRTOS has been used together with a state machine to control the measurements of the sensors of the garments and send the measured values via bluetooth to a mobile application.

In the hardware development, the design and implementation of the PCBs has been carried out.

Finally, we have started to perform unit tests on the development carried out, for the hardware as well as for the software, which should be finalized to verify the complete performance of the developed system.

H2H: Acceso inalámbrico seguro a dispositivos médicos
Posted on by b105

Uno de los proyectos que estamos llevando a cabo en el B105 es el diseño de un sistema de acceso inalámbrico a IMDs (Implantable Medical Devices) controlado por una política de acceso llamada H2H (Heart-To-Heart).

Se trata de un dispositivo que permite el acceso inalámbrico de forma segura a dispositivos médicos como los marcapasos. Aplicando esta política se evitan accesos no autorizados a la vez que se permite acceder a estos dispositivos rápidamente en situaciones de emergencia médica.

Este proyecto comenzó como candidato del Texas Instruments Innovation Challenge – Europe 2015 y finalmente se va a desarrollar como dos Proyectos Fin de Carrera: uno enfocado al diseño de la plataforma hardware, llevado a cabo por Samuel López; y otro a la implementación del software, realizado por Tomás Valencia.

Los avances médicos están haciendo posible el desarrollo de una amplia variedad de dispositivos implantables para tratar enfermedades crónicas, con el marcapasos como el ejemplo más común. Estos pueden ser recargados y configurados de forma no invasiva mediante otros dispositivos externos aunque, desgraciadamente, esta última ventaja es uno de sus mayores inconvenientes, ya que los hace propensos a sufrir ataques.

H2H_black_testUna de las soluciones que existen, la cual implementamos en este proyecto, es la llamada política de acceso Heart-To-Heart. Se trata de una política de acceso “touch to access”, en la que nuestro dispositivo programador es capaz de acceder a un IMD si y sólo si dicho programador tiene un contacto físico significativo con el cuerpo del paciente. La autenticación con el IMD termina cuando el programador deja de estar en contacto con él.

Para realizar el acceso, el programador mide la señal eléctrica del corazón. Cuando se intenta acceder al IMD, este realiza su propia medida y la compara con la del programador. Si ambas son lo suficientemente parecidas, el programador obtiene acceso al dispositivo. En el caso de que el paciente se encuentre en una situación de emergencia médica, el IMD lo detecta y entra en modo promiscuo permitiendo a cualquier programador acceder a él, ya que se entiende que el riesgo de ataque es irrelevante en dicha situación.

Este esquema proporciona un equilibrio entre los requisitos de permisividad durante emergencias y de resistencia a ataques. Además, su política de acceso intenta seguir una regla de sentido común: la posibilidad de tener acceso físico a una persona implica la posibilidad de hacerle daño o curarle.