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Browsing by Author "Azevedo, Nelson"

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  • Biofeedback-based method for real-time fatigue monitoring of knee
    Publication . Franco, Tiago; Henriques, Pedro; Alves, Paulo; Pereira, Maria João; Leitão, Paulo; Azevedo, Nelson
    This paper introduces and implements a method to monitor muscle fatigue in real-time using a wearable biofeedback system to improve muscle rehabilitation treatments. The biofeedback system consists of an electromyography (EMG) sensor to capture muscle activity and two motion sensors to track knee angles. The proposed method for monitoring muscle fatigue involves three steps: (1) recognition of the movement phases during the knee extension exercise; (2) clipping of the EMG signal and calculation of fatigue-related metrics; and (3) normalization of metrics through a calibration process. An experimental session was performed with 10 healthy subjects performing 50 repetitions of the knee extension exercise. Processed data revealed changes in fatigue-related metrics, which align with existing literature. A comparison was also made between real-time and computer processing using raw data. While minor differences were noted between the two processing methods, the mobile app closely mirrored the trajectory of processed data in the cloud, ensuring reliability and consistency. This study advances remote muscle rehabilitation by quantifying muscle fatigue during treatment sessions. Thus, health professionals can tailor treatment plans based on individual patient characteristics, optimizing treatment duration, and reducing injury risk.
    2024Journal article Open access Show more
  • Titanium based dry electrodes for biostimulation and data acquisition
    Publication . Conselheiro, Raul; Lopes, Claudia; Azevedo, Nelson; Leitao, Paulo; Agulhari, Cristiano; Veloso, H.; Vaz, F.; Gonçalves, João Lucas; Franco, Tiago; Oliveira, Leonardo Sestrem de
    Wet electrodes rely on conductive electrolyte gel for proper perfor- mance, usually presenting high setup time and being disposable or requiring time-consuming cleaning methods. Skin irritation and signal quality deterioration are some of the problems that may occur with these electrodes. Therefore, to overcome these drawbacks, 3D printed bases using Fused Deposition Modelling (FDM) with Polylactic acid (PLA), Polyurethane (PU) and Cellulose filaments were functionalized with titanium (Ti) and titanium-nitride (TiN) thin films and dopped with copper (Cu). The electrodes, implemented using different diameters, were used to record electromyography (EMG) signals proceeded by biostimula- tion sessions to access their electrical and mechanical characteristics and com- pare them to that of commercial AgCl/Ag electrodes. The results show that TiN and TiNCu0.45 dry electrodes present results similar to wet AgCl/Ag electrodes for data acquisition. To be comparable to usual carbon electrodes for muscle stimulation, they need some conductivity improvements to lower the necessary voltage. Besides, the endurance of the thin films must be enhanced as well as the adhesion to the polymer.
    2023Conference paper Restricted access Show more