A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves

[EN] Developing new types of optimized electrodes for specific biomedical applications can substantially improve the quality of the sensed signals. Concentric ring electrodes have been shown to provide enhanced spatial resolution to that of conventional disc electrodes. A sensor with different electrode sizes and configurations (monopolar, bipolar, etc.) that provides simultaneous records would be very helpful for studying the best signal-sensing arrangement. A 5-pole electrode with an inner disc and four concentric rings of different sizes was developed and tested on surface intestinal myoelectrical recordings from healthy humans. For good adaptation to a curved body surface, the electrode was screen-printed onto a flexible polyester substrate. To facilitate clinical use, it is self-adhesive, incorporates a single connector and can perform dry or wet (with gel) recordings. The results show it to be a versatile electrode that can evaluate the optimal configuration for the identification of the intestinal slow wave and reject undesired interference. A bipolar concentric record with an outer ring diameter of 30 mm, a foam-free adhesive material, and electrolytic gel gave the best results.Grant from the Ministerio de Economia y Competitividad y del Fondo Europeo de Desarrollo Regional. DPI2015-68397-R (MINECO/FEDER).Zena-Giménez, VF.; Garcia Casado, FJ.; Ye Lin, Y.; Garcia-Breijo, E.; Prats-Boluda, G. (2018). A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves. Sensors. 18(2):396-412. https://doi.org/10.3390/s18020396S39641218

A Measurement System for Detection of Intestinal Motility in Neonates by Monitoring Slow Wave Activity

Similar to how electrocardiographic waves are the pace making signals of the heart, slow waves are the pace making signals of the intestines. Slow waves are electrical signals in the intestines that determine the speed at which food can move through the intestine ensuring proper digestion and uptake of nutrients. It has been shown that slow waves can be measured in adults using non-invasive, surface electrodes. However, no study has investigated the measurements of slow waves in neonates, specifically pre-term neonates. Around 7% of pre-term neonates suffer from necrotizing enterocolitis (NEC) which is a condition that causes damage to the intestinal tract and often death of intestinal tissue. NEC affects around 9,000 neonates each year with a survival rate estimated to be between 60%-80%. Currently, there are no non-invasive, early-stage indicators of NEC. This pilot study aims to create a non-invasive measurement setup to measure and characterize slow wave activity in neonates

Validating the Comparison Framework for the Finite Dimensions Model of Concentric Ring Electrodes Using Human Electrocardiogram Data

[EN] While progress has been made in design optimization of concentric ring electrodes maximizing the accuracy of the surface Laplacian estimation, it was based exclusively on the negligible dimensions model of the electrode. Recent proof of concept of the new finite dimensions model that adds the radius of the central disc and the widths of concentric rings to the previously included number of rings and inter-ring distances provides an opportunity for more comprehensive design optimization. In this study, the aforementioned proof of concept was developed into a framework allowing direct comparison of any two concentric ring electrodes of the same size and with the same number of rings. The proposed framework is illustrated on constant and linearly increasing inter-ring distances tripolar concentric ring electrode configurations and validated on electrocardiograms from 20 human volunteers. In particular, ratios of truncation term coefficients between the two electrode configurations were used to demonstrate the similarity between the negligible and the finite dimension models analytically (p = 0.077). Laplacian estimates based on the two models were calculated on electrocardiogram data for emulation of linearly increasing inter-ring distances tripolar concentric ring electrode. The difference between the estimates was not statistically significant (p >> 0.05) which is consistent with the analytic result.This research was funded by the National Science Foundation (NSF) Division of Human Resource Development (HRD) Tribal Colleges and Universities Program (TCUP), grants number 1622481 and 1914787 to Oleksandr Makeyev. The authors would like to thank Rafael Rodriguez de Sanabria for his help with the human ECG data collection and Eduardo Garcia-Breijo for his help with the CRE implementation.Makeyev, O.; Musngi, M.; Moore, L.; Ye Lin, Y.; Prats-Boluda, G.; Garcia-Casado, J. (2019). Validating the Comparison Framework for the Finite Dimensions Model of Concentric Ring Electrodes Using Human Electrocardiogram Data. Applied Sciences. 9(20):1-14. https://doi.org/10.3390/app9204279S114920Bradshaw, L. A., Richards, W. O., & Wikswo, J. P. (2001). Volume conductor effects on the spatial resolution of magnetic fields and electric potentials from gastrointestinal electrical activity. Medical and Biological Engineering and Computing, 39(1), 35-43. doi:10.1007/bf02345264Besio, W. G., Hongbao Cao, & Peng Zhou. (2008). Application of Tripolar Concentric Electrodes and Prefeature Selection Algorithm for Brain–Computer Interface. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 16(2), 191-194. doi:10.1109/tnsre.2007.916303Farina, D., & Cescon, C. (2001). Concentric-ring electrode systems for noninvasive detection of single motor unit activity. IEEE Transactions on Biomedical Engineering, 48(11), 1326-1334. doi:10.1109/10.959328McFarland, D. J., McCane, L. M., David, S. V., & Wolpaw, J. R. (1997). Spatial filter selection for EEG-based communication. Electroencephalography and Clinical Neurophysiology, 103(3), 386-394. doi:10.1016/s0013-4694(97)00022-2Wu, D., Tsai, H. C., & He, B. (1999). On the Estimation of the Laplacian Electrocardiogram during Ventricular Activation. Annals of Biomedical Engineering, 27(6), 731-745. doi:10.1114/1.224Hjorth, B. (1975). An on-line transformation of EEG scalp potentials into orthogonal source derivations. Electroencephalography and Clinical Neurophysiology, 39(5), 526-530. doi:10.1016/0013-4694(75)90056-5MacKay, D. . (1983). On-line source-density computation with a minimum of electrons. Electroencephalography and Clinical Neurophysiology, 56(6), 696-698. doi:10.1016/0013-4694(83)90040-8Huiskamp, G. (1991). Difference formulas for the surface Laplacian on a triangulated surface. Journal of Computational Physics, 95(2), 477-496. doi:10.1016/0021-9991(91)90286-tBesio, G., Koka, K., Aakula, R., & Weizhong Dai. (2006). Tri-polar concentric ring electrode development for Laplacian electroencephalography. IEEE Transactions on Biomedical Engineering, 53(5), 926-933. doi:10.1109/tbme.2005.863887Besio, W., Aakula, R., Koka, K., & Dai, W. (2006). Development of a Tri-polar Concentric Ring Electrode for Acquiring Accurate Laplacian Body Surface Potentials. Annals of Biomedical Engineering, 34(3), 426-435. doi:10.1007/s10439-005-9054-8Wang, K., Parekh, U., Pailla, T., Garudadri, H., Gilja, V., & Ng, T. N. (2017). Stretchable Dry Electrodes with Concentric Ring Geometry for Enhancing Spatial Resolution in Electrophysiology. Advanced Healthcare Materials, 6(19), 1700552. doi:10.1002/adhm.201700552Lidón-Roger, J., Prats-Boluda, G., Ye-Lin, Y., Garcia-Casado, J., & Garcia-Breijo, E. (2018). Textile Concentric Ring Electrodes for ECG Recording Based on Screen-Printing Technology. Sensors, 18(1), 300. doi:10.3390/s18010300Besio, W. G., Martinez-Juarez, I. E., Makeyev, O., Gaitanis, J. N., Blum, A. S., Fisher, R. S., & Medvedev, A. V. (2014). High-Frequency Oscillations Recorded on the Scalp of Patients With Epilepsy Using Tripolar Concentric Ring Electrodes. IEEE Journal of Translational Engineering in Health and Medicine, 2, 1-11. doi:10.1109/jtehm.2014.2332994Boudria, Y., Feltane, A., & Besio, W. (2014). Significant improvement in one-dimensional cursor control using Laplacian electroencephalography over electroencephalography. Journal of Neural Engineering, 11(3), 035014. doi:10.1088/1741-2560/11/3/035014Garcia-Casado, J., Zena-Gimenez, V., Prats-Boluda, G., & Ye-Lin, Y. (2013). Enhancement of Non-Invasive Recording of Electroenterogram by Means of a Flexible Array of Concentric Ring Electrodes. Annals of Biomedical Engineering, 42(3), 651-660. doi:10.1007/s10439-013-0935-yZena-Giménez, V., Garcia-Casado, J., Ye-Lin, Y., Garcia-Breijo, E., & Prats-Boluda, G. (2018). A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves. Sensors, 18(2), 396. doi:10.3390/s18020396Ye-Lin, Y., Alberola-Rubio, J., Prats-boluda, G., Perales, A., Desantes, D., & Garcia-Casado, J. (2014). Feasibility and Analysis of Bipolar Concentric Recording of Electrohysterogram with Flexible Active Electrode. Annals of Biomedical Engineering, 43(4), 968-976. doi:10.1007/s10439-014-1130-5Prats-Boluda, G., Ye-Lin, Y., Pradas-Novella, F., Garcia-Breijo, E., & Garcia-Casado, J. (2018). Textile Concentric Ring Electrodes: Influence of Position and Electrode Size on Cardiac Activity Monitoring. Journal of Sensors, 2018, 1-9. doi:10.1155/2018/7290867Wang, Y.-C., Chang, C.-F., Lin, H.-C., Lin, K.-S., Lin, K.-T., Hung, C.-M., & Lin, T.-M. (2010). Functional characterisation of a complex mutation in the α(1,4)galactosyltransferase gene in Taiwanese individuals with p phenotype. Transfusion Medicine, 21(2), 84-89. doi:10.1111/j.1365-3148.2010.01055.xMakeyev, O., Ding, Q., & Besio, W. G. (2016). Improving the accuracy of Laplacian estimation with novel multipolar concentric ring electrodes. Measurement, 80, 44-52. doi:10.1016/j.measurement.2015.11.017Makeyev, O., & Besio, W. (2016). Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes. Sensors, 16(6), 858. doi:10.3390/s16060858Makeyev, O. (2018). Solving the general inter-ring distances optimization problem for concentric ring electrodes to improve Laplacian estimation. BioMedical Engineering OnLine, 17(1). doi:10.1186/s12938-018-0549-6Ye-Lin, Y., Bueno-Barrachina, J. M., Prats-boluda, G., Rodriguez de Sanabria, R., & Garcia-Casado, J. (2017). Wireless sensor node for non-invasive high precision electrocardiographic signal acquisition based on a multi-ring electrode. Measurement, 97, 195-202. doi:10.1016/j.measurement.2016.11.009Besio, W., & Chen, T. (2007). Tripolar Laplacian electrocardiogram and moment of activation isochronal mapping. Physiological Measurement, 28(5), 515-529. doi:10.1088/0967-3334/28/5/006Hamilton, P. S., & Tompkins, W. J. (1986). Quantitative Investigation of QRS Detection Rules Using the MIT/BIH Arrhythmia Database. IEEE Transactions on Biomedical Engineering, BME-33(12), 1157-1165. doi:10.1109/tbme.1986.325695Prats-Boluda, G., Ye-Lin, Y., Bueno-Barrachina, J., Rodriguez de Sanabria, R., & Garcia-Casado, J. (2016). Towards the clinical use of concentric electrodes in ECG recordings: influence of ring dimensions and electrode position. Measurement Science and Technology, 27(2), 025705. doi:10.1088/0957-0233/27/2/025705Mittal, S., Movsowitz, C., & Steinberg, J. S. (2011). Ambulatory External Electrocardiographic Monitoring. Journal of the American College of Cardiology, 58(17), 1741-1749. doi:10.1016/j.jacc.2011.07.026Garcia-Casado, J., Ye-Lin, Y., Prats-Boluda, G., & Makeyev, O. (2019). Evaluation of Bipolar, Tripolar, and Quadripolar Laplacian Estimates of Electrocardiogram via Concentric Ring Electrodes. Sensors, 19(17), 3780. doi:10.3390/s19173780Xu, Y., Luo, M., Li, T., & Song, G. (2017). ECG Signal De-noising and Baseline Wander Correction Based on CEEMDAN and Wavelet Threshold. Sensors, 17(12), 2754. doi:10.3390/s17122754Ortigueira, M. D., Laleg-Kirati, T.-M., & Machado, J. A. T. (2014). Riesz potential versus fractional Laplacian. Journal of Statistical Mechanics: Theory and Experiment, 2014(9), P09032. doi:10.1088/1742-5468/2014/09/p0903

Evaluation of Respiratory Muscle Activity by Means of Concentric Ring Electrodes

© 2021 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Surface electromyography (sEMG) can be used for the evaluation of respiratory muscle activity. Recording sEMG involves the use of surface electrodes in a bipolar configuration. However, electrocardiographic (ECG) interference and electrode orientation represent considerable drawbacks to bipolar acquisition. As an alternative, concentric ring electrodes (CREs) can be used for sEMG acquisition and offer great potential for the evaluation of respiratory muscle activity due to their enhanced spatial resolution and simple placement protocol, which does not depend on muscle fiber orientation. The aim of this work was to analyze the performance of CREs during respiratory sEMG acquisitions. Respiratory muscle sEMG was applied to the diaphragm and sternocleidomastoid muscles using a bipolar and a CRE configuration. Thirty-two subjects underwent four inspiratory load spontaneous breathing tests which was repeated after interchanging the electrode positions. We calculated parameters such as (1) spectral power and (2) median frequency during inspiration, and power ratios of inspiratory sEMG without ECG in relation to (3) basal sEMG without ECG (R-ins/noise), (4) basal sEMG with ECG (R-ins/cardio) and (5) expiratory sEMG without ECG (R-ins/exp). Spectral power, R-ins/noise and R-ins/cardio increased with the inspiratory load. Significantly higher values (p < 0.05) of R-ins/cardio and significantly higher median frequencies were obtained for CREs. R-ins/noise and R-ins/exp were higher for the bipolar configuration only in diaphragm sEMG recordings, whereas no significant differences were found in the sternocleidomastoid recordings. Our results suggest that the evaluation of respiratory muscle activity by means of sEMG can benefit from the remarkably reduced influence of cardiac activity, the enhanced detection of the shift in frequency content and the axial isotropy of CREs which facilitates its placement.This work was supported in part by the CERCA Program/Generalitat de Catalunya, in part by the Secretaria d'Universitats i Recerca de la Generalitat de Catalunya under Grant GRC 2017 SGR 01770, in part by the Spanish Grants RTI2018-098472-B-I00, RTI2018-094449-A-I00-AR (MCIU/AEI/FEDER, UE) and DPI2015-68397-R (MINECO/FEDER), and in part by the Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN, Instituto de Salud Carlos III/FEDER). The first author was supported by the IFARHU-SENACYT Scholarship Program from the Panama Government under Grant 270-2012-273.Estrada-Petrocelli, L.; Torres, A.; Sarlabous, L.; Ràfols-De-Urquía, M.; Ye Lin, Y.; Prats-Boluda, G.; Jané, R.... (2021). Evaluation of Respiratory Muscle Activity by Means of Concentric Ring Electrodes. IEEE Transactions on Biomedical Engineering. 68(3):1005-1014. https://doi.org/10.1109/TBME.2020.3012385S1005101468

Diseño e implementación de un sensor Laplaciano activo flexible. Aplicación al estudio del EENG humano en superficie

Gastrointestinal diseases have a complicated diagnosis and a delay in treatment can lead to an aggravation of the disease, as is the case of intestinal ischemia, intestinal obstruction or paralytic ileus. These pathologies are revealed in intestinal motility which is determined by the myoelectric activity of the small intestine. EEnG is the signal associated to the recording of myoelectrical activity generated in the muscular layers of the small bowel, and electroenterography is a technique for the study of intestinal motility. At present, there is no non-invasive system for use in clinical settings that allow the recording of myoelectric intestinal activity. In the first part of this doctoral thesis, it has been tested an array of 3 active flexible concentric electrodes, which preamplifies and conditions the intestinal myoelectric signal captured on the surface as close as possible to the recording area. The results show that in the Laplacian recordings there was a better behavior against the influence of cardiac and respiratory interference with respect to bipolar with disc electrodes. However, in respect to low frequency interferences, concentric dry recording electrodes presented poorer performance than the gel recording disc electrodes. On the other hand, it was possible to identify the slow intestinal wave in about 93% of the analysis windows of the records with the matrix of concentric electrodes, compared to 88% of the bipolar records with disc electrodes. In the second part of the thesis, it has been attempted to improve the quality of the EEnG signals already achieved with the flexible concentric electrodes presented before with the design and implementation of flexible, self-adhesive flexible multi-ring concentric electrodes that can work in wet conditions (impregnation with electrolytic gel) and using two different substrates for the adhesive (adhesive-only and foam). Also it is aimed to determine the optimal configuration (monopolar vs bipolar concentric, MC vs BC) and dimension of ring, the appropriate material and the ideal position for picking up the slow intestinal wave. The adhesive material in concentric bipolar configuration and 30 mm ring diameter was most suitable to capture the slow intestinal wave; with an ability to detect the frequency of slow intestinal wave in a 95% of the cases. Improving 90% of the bipolar registers with conventional disc electrodes in the same position, and the results of the electrode matrix of the first part of the thesis. This work demonstrates the feasibility of recording the abdominal surface EEnG for the noninvasive monitoring of the slow intestinal wave and the better performance of the flexible substrate concentric electrodes compared to that of conventional disc electrodes. This is a further step to bring EEnG closer to clinical use and to the future development of diagnostic applications. In addition, the developed electrode can be used in other applications associated with the recording, monitoring and analysis of bioelectrical signals such as the fields of electrocardiography, uterine electromyography, respiratory muscle, etc.Las patologías gastrointestinales son complicadas en su diagnóstico, y un retraso en el tratamiento puede llevar a un agravamiento de la enfermedad, como ocurre con la isquemia intestinal, la obstrucción intestinal o el íleo paralítico. Estas patologías se ven reflejadas en la motilidad intestinal y ésta está determinada por la actividad mioeléctrica del intestino delgado. El electroenterograma (EEnG) es la señal bioeléctrica asociada al registro de la actividad mioeléctrica intestinal generada en las capas del músculo liso; siendo la electroenterografía una técnica para el estudio de la motilidad intestinal. En la actualidad, no existe un sistema no invasivo de uso en entornos clínicos que permita registrar la actividad mioeléctrica intestinal. En la primera parte de la presente tesis doctoral, se ha ensayado una matriz de 3 electrodos anulares concéntricos, flexibles y activos, que preamplifica y acondiciona la señal mioeléctrica intestinal captada en superficie lo más cerca posible de la zona de captación. Los resultados muestran que en los registros laplacianos se tiene un mejor comportamiento frente a influencia de la interferencia cardiaca y respiratoria con respecto a los bipolares con electrodos de disco. Sin embargo, respecto a las interferencias de baja frecuencia los electrodos concéntricos de registro en seco presentaron peor comportamiento que los electrodos de disco de registro con gel. Por otro lado, fue posible identificar la onda lenta intestinal en alrededor del 93% de las ventanas de análisis de los registros con la matriz de electrodos concéntricos, frente al 88% de los registros bipolares con electrodos de disco. En la segunda parte de la tesis se ha pretendido mejorar la calidad en la captación de las señales EEnG captada con los electrodos concéntricos flexibles presentados anteriormente, con el diseño e implementación de electrodos concéntricos multianulares flexibles, autoadhesivos, que puedan trabajar en húmedo (impregnación con gel electrolítico) y empleando dos sustratos diferentes para el adhesivo (solo-adhesivo vs foam). Asimismo, se pretende determinar la dimensión y configuración (monopolar vs bipolar concéntrico, MC vs BC) óptima, el material adecuado y la posición idónea para la captación de la onda lenta intestinal con electrodos anulares. El material adhesivo en configuración bipolar concéntrica y de diámetro de 30 mm fue el más idóneo para captar la onda lenta intestinal, con una capacidad de detectar la frecuencia asociada a la onda lenta intestinal en un 95% de los casos; mejorando el 90% de los registros bipolares con electrodos convencionales de disco en la misma posición, y los resultados de la matriz de electrodos de la primera parte de la tesis. Con este trabajo se pone de manifiesto la viabilidad del registro del EEnG en superficie abdominal para la monitorización no invasiva de la onda lenta intestinal y las mejores prestaciones de los electrodos concéntricos de sustrato flexible frente a los convencionales electrodos de disco. Esto supone un paso más para acercar el EEnG al uso clínico y al desarrollo de futuras aplicaciones diagnósticas. Además, el electrodo desarrollado es susceptible de ser empleado en otras aplicaciones asociadas al registro, monitorización y análisis de señales bioeléctricas como la electrocardiografía, electromiografía uterina, de músculo respiratorio, etcLes patologies gastrointestinals són complicades en el seu diagnòstic, i un retard en el tractament pot portar a un agreujament de la malaltia, com passa amb la isquèmia intestinal, l'obstrucció intestinal o l'ili paralític. Aquestes patologies es veuen reflectides en la motilitat intestinal i aquesta està determinada per l'activitat mioelèctrica de l'intestí prim. L'electroenterograma (EEnG) és el senyal bioelèctric associat al registre de l'activitat mioelèctrica intestinal generada a les capes del múscul llis; sent la electroenterografia una tècnica per a l'estudi de la motilitat intestinal. A la primera part de la present tesi doctoral, s'ha assajat una matriu de 3 elèctrodes anulars concèntrics, flexibles i actius, que preamplifica i condiciona els senyals mioelèctrics intestinals captats en superfície el més a prop possible de la zona de captació. Els resultats mostren que als registres laplacians es té un millor comportament enfront de influència de la interferència cardíaca i respiratòria respecte dels senyals bipolars captats amb elèctrodes de disc. No obstant això, respecte a les interferències de baixa freqüència, els elèctrodes concèntrics de registre en sec van presentar pitjor comportament que els elèctrodes de disc de registre amb gel. D'altra banda, va ser possible identificar l'ona lenta intestinal en al voltant del 93% de les finestres d'anàlisi dels registres realitzats amb la matriu d'elèctrodes concèntrics, enfront del 88% dels registres bipolars amb elèctrodes de disc. A la segona part de la tesi s'ha pretès millorar la qualitat en la captació dels senyals EEnG captada amb els elèctrodes concèntrics flexibles presentats anteriorment, amb el disseny i la implementació d'elèctrodes concèntrics multianulars flexibles, autoadhesius, que puguin treballar en humit (impregnació amb gel electrolític) i emprant dos substrats diferents per l'adhesiu (només-adhesiu vs foam). Així mateix, es pretén determinar la dimensió i configuració (monopolar vs bipolar concèntric, MC vs BC) òptima, el material adequat i la posició idònia per a la captació de l'ona lenta intestinal amb elèctrodes anulars. El material adhesiu en configuració bipolar concèntrica i de diàmetre de 30 mm era el més idoni per captar l'ona lenta intestinal, amb una capacitat de detectar la freqüència associada a l'ona lenta intestinal en un 95% dels casos; millorant el 90% dels registres bipolars amb elèctrodes convencionals de disc en la mateixa posició, i els resultats de la matriu d'elèctrodes de la primera part de la tesi. Amb aquest treball es posa de manifest la viabilitat del registre de l'EEnG en superfície abdominal per a la monitorització no invasiva de l'ona lenta intestinal i les millors prestacions dels elèctrodes concèntrics de substrat flexible enfront dels convencionals elèctrodes de disc. Això suposa un pas més per apropar el EEnG a l'ús clínic i al desenvolupament de futures aplicacions diagnòstiques. A més, l'elèctrode desenvolupat és susceptible de ser emprat en altres aplicacions associades al registre, monitorització i anàlisi de senyals bioelèctrics com a l'electrocardiografia, electromiografia uterina, de múscul respiratori, etc.Zena Giménez, VF. (2017). Diseño e implementación de un sensor Laplaciano activo flexible. Aplicación al estudio del EENG humano en superficie [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86171TESI

Evaluation of Bipolar, Tripolar, and Quadripolar Laplacian Estimates of Electrocardiogram via Concentric Ring Electrodes

[EN] Surface Laplacian estimates via concentric ring electrodes (CREs) have proven to enhance spatial resolution compared to conventional disc electrodes, which is of great importance for P-wave analysis. In this study, Laplacian estimates for traditional bipolar configuration (BC), two tripolar configurations with linearly decreasing and increasing inter-ring distances (TCLDIRD and TCLIIRD, respectively), and quadripolar configuration (QC) were obtained from cardiac recordings with pentapolar CREs placed at CMV1 and CMV2 positions. Normalized P-wave amplitude (NAP) was computed to assess the contrast to study atrial activity. Signals were of good quality (20-30 dB). Atrial activity was more emphasized at CMV1 (NAP similar or equal to 0.19-0.24) compared to CMV2 (NAP similar or equal to 0.08-0.10). Enhanced spatial resolution of TCLIIRD and QC resulted in higher NAP values than BC and TCLDIRD. Comparison with simultaneous standard 12-lead ECG proved that Laplacian estimates at CMV1 outperformed all the limb and chest standard leads in the contrast to study P-waves. Clinical recordings with CRE at this position could allow more detailed observation of atrial activity and facilitate the diagnosis of associated pathologies. Furthermore, such recordings would not require additional electrodes on limbs and could be performed wirelessly, so it should also be suitable for ambulatory monitoring, for example, using cardiac Holter monitors.This research was funded by the National Science Foundation (NSF) Division of Human Resource Development (HRD) Tribal Colleges and Universities Program (TCUP), grants number 1622481 and 1914787 to O.M.Garcia-Casado, J.; Ye Lin, Y.; Prats-Boluda, G.; Makeyev, O. (2019). Evaluation of Bipolar, Tripolar, and Quadripolar Laplacian Estimates of Electrocardiogram via Concentric Ring Electrodes. 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IEEE Transactions on Biomedical Engineering, 53(5), 926-933. doi:10.1109/tbme.2005.863887Besio, W., Aakula, R., Koka, K., & Dai, W. (2006). Development of a Tri-polar Concentric Ring Electrode for Acquiring Accurate Laplacian Body Surface Potentials. Annals of Biomedical Engineering, 34(3), 426-435. doi:10.1007/s10439-005-9054-8Besio, W., & Chen, T. (2007). Tripolar Laplacian electrocardiogram and moment of activation isochronal mapping. Physiological Measurement, 28(5), 515-529. doi:10.1088/0967-3334/28/5/006Prats-Boluda, G., Garcia-Casado, J., Martinez-de-Juan, J. L., & Ye-Lin, Y. (2011). Active concentric ring electrode for non-invasive detection of intestinal myoelectric signals. Medical Engineering & Physics, 33(4), 446-455. doi:10.1016/j.medengphy.2010.11.009Prats-Boluda, G., Ye-Lin, Y., Bueno-Barrachina, J., Rodriguez de Sanabria, R., & Garcia-Casado, J. (2016). Towards the clinical use of concentric electrodes in ECG recordings: influence of ring dimensions and electrode position. Measurement Science and Technology, 27(2), 025705. doi:10.1088/0957-0233/27/2/025705Zena-Giménez, V., Garcia-Casado, J., Ye-Lin, Y., Garcia-Breijo, E., & Prats-Boluda, G. (2018). A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves. Sensors, 18(2), 396. doi:10.3390/s18020396Ye-Lin, Y., Alberola-Rubio, J., Prats-boluda, G., Perales, A., Desantes, D., & Garcia-Casado, J. (2014). Feasibility and Analysis of Bipolar Concentric Recording of Electrohysterogram with Flexible Active Electrode. Annals of Biomedical Engineering, 43(4), 968-976. doi:10.1007/s10439-014-1130-5Wang, K., Parekh, U., Pailla, T., Garudadri, H., Gilja, V., & Ng, T. N. (2017). Stretchable Dry Electrodes with Concentric Ring Geometry for Enhancing Spatial Resolution in Electrophysiology. 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Evaluation of Swallowing Related Muscle Activity by Means of Concentric Ring Electrodes

[EN] Surface electromyography (sEMG) can be helpful for evaluating swallowing related muscle activity. Conventional recordings with disc electrodes suffer from significant crosstalk from adjacent muscles and electrode-to-muscle fiber orientation problems, while concentric ring electrodes (CREs) offer enhanced spatial selectivity and axial isotropy. The aim of this work was to evaluate CRE performance in sEMG recordings of the swallowing muscles. Bipolar recordings were taken from 21 healthy young volunteers when swallowing saliva, water and yogurt, first with a conventional disc and then with a CRE. The signals were characterized by the root-mean-square amplitude, signal-to-noise ratio, myopulse, zero-crossings, median frequency, bandwidth and bilateral muscle cross-correlations. The results showed that CREs have advantages in the sEMG analysis of swallowing muscles, including enhanced spatial selectivity and the associated reduction in crosstalk, the ability to pick up a wider range of EMG frequency components and easier electrode placement thanks to its radial symmetry. However, technical changes are recommended in the future to ensure that the lower CRE signal amplitude does not significantly affect its quality. CREs show great potential for improving the clinical monitoring and evaluation of swallowing muscle activity. Future work on pathological subjects will assess the possible advantages of CREs in dysphagia monitoring and diagnosis.This work was supported by the Spanish Ministry of the Economy and Competitiveness, the European Regional Development Fund (MCIU/AEI/FEDER, UE RTI2018-094449-A-I00-AR).Garcia-Casado, J.; Prats-Boluda, G.; Ye Lin, Y.; Restrepo-Agudelo, S.; Perez-Giraldo, E.; Orozco-Duque, A. (2020). 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S., Jaffe, D., & McCulloch, T. M. (1999). Contributions of Individual Muscles to the Submental Surface Electromyogram During Swallowing. Journal of Speech, Language, and Hearing Research, 42(6), 1378-1391. doi:10.1044/jslhr.4206.1378Stepp, C. E. (2012). Surface Electromyography for Speech and Swallowing Systems: Measurement, Analysis, and Interpretation. Journal of Speech, Language, and Hearing Research, 55(4), 1232-1246. doi:10.1044/1092-4388(2011/11-0214)He, B., & Cohen, R. J. (1992). Body surface Laplacian ECG mapping. IEEE Transactions on Biomedical Engineering, 39(11), 1179-1191. doi:10.1109/10.168684Koka, K., & Besio, W. G. (2007). Improvement of spatial selectivity and decrease of mutual information of tri-polar concentric ring electrodes. Journal of Neuroscience Methods, 165(2), 216-222. doi:10.1016/j.jneumeth.2007.06.007Farina, D., Cescon, C., & Merletti, R. (2002). Influence of anatomical, physical, and detection-system parameters on surface EMG. Biological Cybernetics, 86(6), 445-456. doi:10.1007/s00422-002-0309-2Garcia-Casado, J., Ye-Lin, Y., Prats-Boluda, G., & Makeyev, O. (2019). Evaluation of Bipolar, Tripolar, and Quadripolar Laplacian Estimates of Electrocardiogram via Concentric Ring Electrodes. Sensors, 19(17), 3780. doi:10.3390/s19173780Toole, C., Martinez-Juárez, I. E., Gaitanis, J. N., Blum, A., Sunderam, S., Ding, L., … Besio, W. G. (2019). Source localization of high-frequency activity in tripolar electroencephalography of patients with epilepsy. Epilepsy & Behavior, 101, 106519. doi:10.1016/j.yebeh.2019.106519Lidón-Roger, J., Prats-Boluda, G., Ye-Lin, Y., Garcia-Casado, J., & Garcia-Breijo, E. (2018). Textile Concentric Ring Electrodes for ECG Recording Based on Screen-Printing Technology. Sensors, 18(1), 300. doi:10.3390/s18010300Aghaei-Lasboo, A., Inoyama, K., Fogarty, A. S., Kuo, J., Meador, K. J., Walter, J. J., … Fisher, R. S. (2020). Tripolar concentric EEG electrodes reduce noise. Clinical Neurophysiology, 131(1), 193-198. doi:10.1016/j.clinph.2019.10.022Li, G., Wang, Y., Lin, L., Jiang, W., Wang, L. L., Lu, S. C.-Y., & Besio, W. G. (2005). Active Laplacian electrode for the data-acquisition system of EHG. Journal of Physics: Conference Series, 13, 330-335. doi:10.1088/1742-6596/13/1/077Ye-Lin, Y., Alberola-Rubio, J., Prats-boluda, G., Perales, A., Desantes, D., & Garcia-Casado, J. (2014). Feasibility and Analysis of Bipolar Concentric Recording of Electrohysterogram with Flexible Active Electrode. Annals of Biomedical Engineering, 43(4), 968-976. doi:10.1007/s10439-014-1130-5Zena-Giménez, V., Garcia-Casado, J., Ye-Lin, Y., Garcia-Breijo, E., & Prats-Boluda, G. (2018). A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves. Sensors, 18(2), 396. doi:10.3390/s18020396Garcia-Casado, J., Zena-Gimenez, V., Prats-Boluda, G., & Ye-Lin, Y. (2013). Enhancement of Non-Invasive Recording of Electroenterogram by Means of a Flexible Array of Concentric Ring Electrodes. Annals of Biomedical Engineering, 42(3), 651-660. doi:10.1007/s10439-013-0935-yCastroflorio, T., Deregibus, A., Bargellini, A., Debernardi, C., & Manfredini, D. (2014). Detection of sleep bruxism: comparison between an electromyographic and electrocardiographic portable holter and polysomnography. Journal of Oral Rehabilitation, 41(3), 163-169. doi:10.1111/joor.12131Lee, Y., Nicholls, B., Sup Lee, D., Chen, Y., Chun, Y., Siang Ang, C., & Yeo, W.-H. (2017). Soft Electronics Enabled Ergonomic Human-Computer Interaction for Swallowing Training. Scientific Reports, 7(1). doi:10.1038/srep46697Kim, M. K., Kantarcigil, C., Kim, B., Baruah, R. K., Maity, S., Park, Y., … Lee, C. H. (2019). Flexible submental sensor patch with remote monitoring controls for management of oropharyngeal swallowing disorders. 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Development of sEMG sensors and algorithms for silent speech recognition. Journal of Neural Engineering, 15(4), 046031. doi:10.1088/1741-2552/aac965Phinyomark, A., Phukpattaranont, P., & Limsakul, C. (2012). Feature reduction and selection for EMG signal classification. Expert Systems with Applications, 39(8), 7420-7431. doi:10.1016/j.eswa.2012.01.102Liu, X., Makeyev, O., & Besio, W. (2020). Improved Spatial Resolution of Electroencephalogram Using Tripolar Concentric Ring Electrode Sensors. Journal of Sensors, 2020, 1-9. doi:10.1155/2020/6269394Farina, D., Arendt-Nielsen, L., Merletti, R., Indino, B., & Graven-Nielsen, T. (2003). Selectivity of spatial filters for surface EMG detection from the tibialis anterior muscle. IEEE Transactions on Biomedical Engineering, 50(3), 354-364. doi:10.1109/tbme.2003.808830Wang, K., Parekh, U., Pailla, T., Garudadri, H., Gilja, V., & Ng, T. N. (2017). 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A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves

Developing new types of optimized electrodes for specific biomedical applications can substantially improve the quality of the sensed signals. Concentric ring electrodes have been shown to provide enhanced spatial resolution to that of conventional disc electrodes. A sensor with different electrode sizes and configurations (monopolar, bipolar, etc.) that provides simultaneous records would be very helpful for studying the best signal-sensing arrangement. A 5-pole electrode with an inner disc and four concentric rings of different sizes was developed and tested on surface intestinal myoelectrical recordings from healthy humans. For good adaptation to a curved body surface, the electrode was screen-printed onto a flexible polyester substrate. To facilitate clinical use, it is self-adhesive, incorporates a single connector and can perform dry or wet (with gel) recordings. The results show it to be a versatile electrode that can evaluate the optimal configuration for the identification of the intestinal slow wave and reject undesired interference. A bipolar concentric record with an outer ring diameter of 30 mm, a foam-free adhesive material, and electrolytic gel gave the best results