2023
Autores
Rodrigues, C; Correia, M; Abrantes, J; Rodrigues, M; Nadal, J;
Publicação
Lecture Notes in Bioengineering
Abstract
This study presents and applies cross-correlation analysis of lower limb joint angular kinematic signal for coordination assessment during impulse phase of standard Maximum Vertical Jump (MVJ). Standard MVJ has been applied for noninvasive subject specific analysis at Counter Movement Jump (CMJ) and Drop Jump (DJ) with long and short Counter Movement (CM) for comparison with Squat Jump (SJ) and no CM. Long and short CM are intrinsically related to the underlying mechanisms of muscle Stretch–Shortening Cycle (SSC) with the integration of muscular action and synergistic joint coordination an open issue on the contribution for the task to perform. Lower limb joint coordination has thus received increasing research interest as an external observed result of the neuromuscular control mechanisms and the hypotheses of training and repetition contribution for stereotyped coordination with the need of objective tools considering entire time series while avoiding subjective point selection for coordination assessment. The results of maximum cross-correlation (CCr max) and corresponding time delay (t) from entire time series of the Hip (H), the Knee (K) and the Ankle (A) joints angular displacement (?), angular velocities (?) and angular accelerations (a) during a fifty-four trial sample with long, short and no CM performed by a group of healthy untrained subjects conduced to detection of maximum synchrony with null t of the lower limb ? at different conditions, whereas ? and a CCr led to detection of different time delay for CCr max with dominant negative t values corresponding to a proximal–distal coordination sequence at H–K-A. These results point thus for the need to consider entire time series of joint ? and a in addition to joint ? to detect different joint coordination and avoid subjective point selection for coordination assessment. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.
2023
Autores
Rodrigues, C; Correia, M; Abrantes, J; Rodrigues, M; Nadal, J;
Publicação
Lecture Notes in Bioengineering
Abstract
This study presents and applies global metrics for the analysis of the center of pressure (COP) excursion during impulse phases at different standard maximum vertical jump (MVJ) with long, short and no countermovement (CM) at countermovement jump (CMJ), drop jump (DJ) and squat jump (SJ) expanding COP analysis from static to dynamic condition of CM in association with lower limb muscle stretch–shortening cycle (SSC) and complementing previous studies on time structural analysis of COP excursion during impulse phase at standard MVJ. Whereas literature is abundant on COP excursion at gait, run and orthostatic standing position, there is a lack of studies on COP analysis at standard MVJ with an open issue on its contribution to long, short and no CM performance. Fifty-four trial tests were assessed with the selection of the best CMJ, DJ and SJ for each subject based on vertical flight height hflight. During trial tests ground reaction forces (GRF) and force moments were acquired and the COP coordinates were computed during the impulse phases. COP stabilograms and statokinesigrams were plotted and global metrics were computed namely the COPxA antero-posterior and COPyA mediolateral amplitudes of COP excursion, mean radial distance R, the length L of the path and the average velocity v during COP excursion. Statistical significative differences were detected at 5% significance, with higher mean COPxA than COPyA and higher mean COP global metrics at CMJ than SJ both higher than DJ, with DJ higher velocity of COP excursion than CMJ both higher than SJ. Global correlational analysis presented a positive linear association of COP metrics with hflight whereas at segmented MVJ this association wasn’t detected, thus rejecting the negative impact of larger COP excursion on MVJ performance. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.
2023
Autores
Gouveia, AR; Oliveira, W; Correia, MV;
Publicação
2023 45TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY, EMBC
Abstract
Due to the growth observed in the wearable market, stretchable strain sensors have been the focus of several studies. However, combining high sensitivity and linearity with low hysteresis presents a difficult challenge. Here, we propose a stretchable strain sensor obtained with off-the-shelf materials by printing a carbon conductive paste into a piece of fabric to be integrated into a smart garment. This process is cheap and easily scalable, allowing its mass production. The sensor developed has a large sensitivity (GF=11.27), high linearity (R-2>0.99), very low hysteresis (gamma(H) = 4.23%) and brings an added value, for example, in sports or rehabilitation monitoring.
2024
Autores
Rodrigues, C; Correia, M; Abrantes, J; Rodrigues, M; Nadal, J;
Publicação
2024 IEEE 22nd Mediterranean Electrotechnical Conference, MELECON 2024
Abstract
This study presents variability assessment of real time measurements from in-vivo internal joint loads with instrumented implant during post-operative (PO) recovery process from total hip arthroplasty on daily living gait activities. A total of 112 trials walking supported by crutches in both hands, contralateral and ipsilateral sides, walking on treadmill at constant velocities, accelerating, decelerating and free walking, were assessed from 9 different patients ranging 0.3 to 76-month PO. Variability was assessed based on standard deviation of the vertical joint load normalized to each subject body weight with this metric adequacy to monitor PO recover. © 2024 IEEE.
2024
Autores
Santos Silva, AD; Correia, MV; Da Silva, HP;
Publicação
2024 IEEE 22nd Mediterranean Electrotechnical Conference, MELECON 2024
Abstract
In our previous work, we explored a new invisible ECG biometrics approach that uses signals collected at the thighs using polymeric dry electrodes and sensors integrated into a toilet seat. However, the performance of the biometric templates remains unexplored. In this paper we evaluate how the ECG templates evolve, and the impact that potential changes may have on performance, using one case-study subject monitored over 31 days. This work is organized into two main parts. The first explores the morphological and physical traits of the subject throughout the 31 days based on data collected daily, three times per day at 6-hour intervals; in more than 80% of the sessions, all the signals were successfully acquired without showing noise nor movement artefacts. The second part is focused on evaluating the performance of Support Vector Machine (SVM) and Binary Convolutional Neural Network (BCNN) classifiers in the identification of the case study subject within a population of 10 individuals, covering an age range of (24 to 35 years); the top performer was the BCNN, achieving a perfect accuracy rate of 100% when tested on a group of two individuals. © 2024 IEEE.
2024
Autores
Fonseca, P; Goethel, MF; Vilas-Boas, JP; Gutierres, M; Correia, MV;
Publicação
BIOENGINEERING-BASEL
Abstract
The electrical stimulation of pedicle screws is a technique used to ensure its correct placement within the vertebrae pedicle. Several authors have studied these screws' electrical properties with the objective of understanding if they are a potential source of false negatives. As titanium screws are anodized with different thicknesses of a high electrical resistance oxide (TiO2), this study investigated, using analytical, numerical, and experimental methods, how its thickness may affect pedicle screw's resistance and conductivity. Analytical results have demonstrated that the thickness of the TiO2 layer does result in a significant radial resistance increase (44.21 m Omega/nm, for & Oslash; 4.5 mm), and a decrease of conductivity with layers thicker than 150 nm. The numerical approach denotes that the geometry of the screw further results in a decrease in the pedicle screw conductivity, especially after 125 nm. Additionally, the experimental results demonstrate that there is indeed an effective decrease in conductivity with an increase in the TiO2 layer thickness, which is also reflected in the screw's total resistance. While the magnitude of the resistance associated with each TiO2 layer thickness may not be enough to compromise the ability to use anodized pedicle screws with a high-voltage electrical stimulator, pedicle screws should be the subject of more frequent electrical characterisation studies.
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