72 research outputs found
Stretchable Surface Electromyography Electrode Array Based on Liquid Metal and Conductive Polymer
Electromyography (EMG), the science of detecting and interpreting muscle electrical activity, plays a crucial role in clinical diagnostics and research. It enables assessment of muscle function, detection of abnormalities, and monitoring of rehabilitation progress. However, the current use of EMG devices is primarily limited to clinical settings, preventing its potential to revolutionize personal health management. If surface electromyography (sEMG) electrodes are stretchable, arrayed, reusable and able to continuously record, their applications for personal health management are broadened. Existing electrodes lack these essential features, hampering their widespread adoption. This thesis addresses these limitations by designing an adhesive dry electrode using tannic acid, polyvinyl alcohol, and PEDOT:PSS (TPP). Through meticulous optimization, TPP electrodes offer superior stretchability and adhesiveness compared to conventional Ag/AgCl electrodes. This ensures stable and long-term skin contact for recording. Furthermore, a metal-polymer electrode array patch (MEAP) is introduced, featuring liquid metal (LM) circuits and TPP electrodes. MEAPs exhibit better conformability than current commercial arrays, resulting in higher signal quality and stable recordings, even during significant skin deformations caused by muscle movements. Manufactured using scalable screen-printing, MEAPs combine stretchable materials and array architecture for real-time monitoring of muscle stress, fatigue, and tendon displacement. They hold great promise in reducing muscle and tendon injuries and enhancing performance in both daily exercise and professional sports. In addition, a pilot study compares MEAP performance in clinical electrodiagnostics with needle electrodes, demonstrating the non-invasive advantage of MEAP by successfully recording the signals from the same motor unit as the needle. These advancements position MEAP at the forefront of the EMG field, poised to drive breakthroughs in electrodiagnostics, personalized medicine, sports science, and rehabilitation
The status of textile-based dry EEG electrodes
Electroencephalogram (EEG) is the biopotential recording of electrical signals generated by brain activity. It is useful for monitoring sleep quality and alertness, clinical applications, diagnosis, and treatment of patients with epilepsy, disease of Parkinson and other neurological disorders, as well as continuous monitoring of tiredness/ alertness in the field. We provide a review of textile-based EEG. Most of the developed textile-based EEGs remain on shelves only as published research results due to a limitation of flexibility, stickability, and washability, although the respective authors of the works reported that signals were obtained comparable to standard EEG. In addition, nearly all published works were not quantitatively compared and contrasted with conventional wet electrodes to prove feasibility for the actual application. This scenario would probably continue to give a publication credit, but does not add to the growth of the specific field, unless otherwise new integration approaches and new conductive polymer composites are evolved to make the application of textile-based EEG happen for bio-potential monitoring
Conception, development and evaluation of polymer-based screen-printed textile electrodes for biopotential monitoring
Wearable technologies represent the new frontier of vital signs monitoring in different
applications, from fitness to health. With the progressive miniaturization of the electronic
components, enabling the implementation of portable and hand-held acquisition and recording
devices, the research focus has shifted toward the development of effective and unobtrusive
textile electrodes. This work deals with the study, development and characterization of
organic-polymer-based electrodes for biopotentials.
After an overview of the main materials and fabrication technologies presented so far in
the scientific literature, the possibility to use these electrodes as an alternative to the Ag/AgCl
disposable gelled electrodes usually adopted in clinical practice was tested. For this purpose,
several textile electrode realization techniques were studied and optimized, in order to create
electrodes with adequate features to detect two fundamental physiological signals: the electrocardiogram
(ECG) and the electromyogram (EMG). The electrodes were obtained by depositing
on the fabric the organic bio-compatible polymer poly(3,4-ethylenedioxythiophene)
doped with poly(4-styrenesulfonate) (PEDOT:PSS) with three deposition procedures: dipcoating,
ink-jet printing and screen printing. The physical\u2013chemical properties of the polymer
solution were varied for each procedure to obtain an optimal and reproducible result. For
what concerns the ECG signal, the research activity focused on screen-printed textile electrodes
and their performance was first assessed by benchtop measurements and then by
human trials. The first tests demonstrated that, by adding solid or liquid electrolytes the
electrodes, the largest part of the characteristics required by the ANSI/AAMI EC12:2000
standard for gelled ECG electrodes can be achieved. Tests performed in different conditions
showed that the skin contact impedance and the ECG morphological features are highly
similar to those obtainable with disposable gelled Ag/AgCl electrodes (\u3c1 > 0.99). A trial
with ten subjects revealed also the capability of the proposed electrodes to accurately capture
with clinical instruments an ECG morphology with performance comparable to off-the-shelf
disposable electrodes. Furthermore, the proposed textile electrodes preserve their electrical
properties and functionality even after several mild washing cycles, while they suffered
physical stretching.
Similar tests were performed on screen-printed textile electrodes fabricated in two different
sizes to test them as EMG sensors, with and without electrolytes. After a series of
controlled acquisitions performed by electro-stimulating the muscles in order to analyze the
waveform morphologu of the M-wave, the statistical analysis showed a high similarity in
terms of rms of the noise and electrode-skin impedance between conventional and textile
electrodes with the addition of solid hydrogel and saline solution. Furthermore, the M-wave
recorded on the tibialis anterior muscle during the stimulation of the peroneal nerve was
comparatively analyzed between conventional and textile electrodes. The comparison provided
an R2 value higher than 97% in all measurement conditions. These results opened their
use in smart garments for real application scenarios and for this purpose were developed a
couple of smart shirts able to detect the EGC and the EMG signal. The results indicated that
this approach could be adopted in the future for the development of smart garments able to
comfortably detect physiological signals
Madden, Julia; O'Mahony, Conor; Thompson, Michael; O'Riordan, Alan; Galvin, Paul
This article explores recent advances in the development of electrochemical biosensors on microneedle platforms towards on-device sensing of biomarkers present in dermal interstitial fluid. The integration of a biosensor with a microneedle platform opens the possibility for minimally invasive bio-chemical detection or continuous monitoring within the dermal interstitial fluid. An introduction to interstitial fluid is provided placing emphasis on sampling methods that have been employed to extract and/or sample tissue fluid for analysis. We look briefly at microneedle technologies used to extract dermal interstitial fluid for subsequent analysis. Successive content will focus on microneedle technologies which have been integrated with electrochemical biosensors for the quantification of various metabolites, electrolytes and other miscellaneous entities known to be present in the dermal interstitial fluid. The review concludes with some of the key challenges and opportunities faced by this next-generation wearable sensing technology
Computational Intelligence in Electromyography Analysis
Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG may be used clinically for the diagnosis of neuromuscular problems and for assessing biomechanical and motor control deficits and other functional disorders. Furthermore, it can be used as a control signal for interfacing with orthotic and/or prosthetic devices or other rehabilitation assists. This book presents an updated overview of signal processing applications and recent developments in EMG from a number of diverse aspects and various applications in clinical and experimental research. It will provide readers with a detailed introduction to EMG signal processing techniques and applications, while presenting several new results and explanation of existing algorithms. This book is organized into 18 chapters, covering the current theoretical and practical approaches of EMG research
Poly (3,4-ethylenedioxythiophene) (PEDOT) Coatings for High Quality Electromyography Recording
Les revĂȘtements en polymĂšre conducteur sur les Ă©lectrodes mĂ©talliques constituent une solution
efficace pour améliorer l'enregistrement et la stimulation des signaux neuronaux en raison de leurs
conductivités électronique et ionique ainsi que de leur biocompatibilité.
Cependant, trĂšs peu dâĂ©tudes ont Ă©tĂ© rĂ©alisĂ©es sur les revĂȘtements de polymĂšres conducteurs sur
des fils métalliques pour l'enregistrement du signal musculaire. Ces travaux traitent surtout les
électrodes pour l'enregistrement chronique sous anesthésie. L'enregistrement chronique du signal
musculaire chez les animaux en mouvement pose un de dĂ©fis pour les revĂȘtements d'Ă©lectrode, en
raison des dĂ©placements musculaires qui peuvent provoquer un dĂ©laminage du revĂȘtement et une
défaillance du dispositif. De plus, la faible adhérence des polymÚres conducteurs à certains
substrats inorganiques et la dégradation de leurs propriétés électrochimiques aprÚs des traitements
sévÚres tels que la stérilisation ou pendant l'implantation, limitent davantage leur utilisation pour
les applications biomédicales.
Dans ce travail, nous avons développé des électrodes invasives électrochimiquement stables pour
l'enregistrement de signaux musculaires chez les petits animaux Ă base de fils multibrins en acier
inoxydable revĂȘtus du polymĂšre conducteur poly(3,4-ethylenedioxythiophene) (PEDOT). La
stabilité électrochimique et mécanique a été obtenue en ajustant les conditions
d'électropolymérisation. Le PEDOT, dopé par des anions ClO4
- , a été électropolymérisé de
maniÚre galvanostatique sur des fils d'acier inoxydable en utilisant trois solvants différents: le
carbonate de propylĂšne (organique), l'acĂ©tonitrile (organique) et l'eau (inorganique). LâadhĂ©rence
du revĂȘtement au substrat mĂ©tallique a Ă©tĂ© testĂ©e par ultrasonication et la stabilitĂ© Ă©lectrochimique
a été évaluée par vieillissement accéléré dans une solution tampon de phosphate salin et par
stĂ©rilisation Ă lâautoclave.
Le solvant a jouĂ© un rĂŽle clĂ© dans lâadhĂ©rence du revĂȘtement PEDOT. Les solvants organiques
offraient la meilleure stabilité mécanique. Les électrodes préparées avec ces solvants possédaient
une excellente stabilité électrochimique et survivaient à la stérilisation et au trempage prolongé
sans changement majeur des propriétés électrochimiques.
Des Ă©lectrodes en acier inoxydable sans revĂȘtements de polymĂšres conducteurs et dâautres revĂȘtues
de PEDOT ont été implantées dans le muscle acromiotrapezius de cinq souris pour l'enregistrement
du signal musculaire durant une pĂ©riode de 6 semaines. Le revĂȘtement PEDOT a amĂ©liorĂ© les
propriétés électrochimiques des électrodes en acier inoxydable, abaissant l'impédance, ce qui a
permis d'améliorer le rapport signal / bruit lors de l'enregistrement du signal musculaire in vivo par
rapport aux Ă©lectrodes sans polymĂšre.----------ABSTRACT
Conductive polymer coatings on metal electrodes are an efficient solution to improve neural signal
recording and stimulation due to their mixed electronic-ionic conduction and biocompatibility.
To date only a few studies have been reported on conductive polymer coatings on metallic wire
electrodes for muscle signal recording. These studies mainly deal with testing of electrodes for
acute recording during anaesthesia. Chronic muscle signal recording in free-walking animals offers
more challenges for the electrode coatings, due to the muscle displacements which may cause
coating delamination and device failure. The poor adhesion of conductive polymers to some
inorganic substrates and the possible degradation of their electrochemical properties after harsh
treatments, such as sterilization, or during implantation still limit their use for biomedical
applications.
In this work, we developed mechanically and electrochemically stable invasive electrodes for
muscle signal recording in small animals based on stainless steel multi-stranded wires coated with
the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). The electrochemical and
mechanical stability was achieved by tuning the electropolymerization conditions. PEDOT doped
with ClO4
- anions was galvanostatically electropolymerized using three different solvents:
propylene carbonate (organic), acetonitrile (organic) and water (inorganic). The coatingâs adhesion
to the metallic substrate was tested through ultrasonication and the electrochemical stability was
evaluated through accelerated ageing in phosphate buffer solution and autoclave sterilization.
The solvent played a key role in the adhesion of the PEDOT coating, with organic solvents giving
the best mechanical stability. Electrodes prepared with these solvents possessed excellent
electrochemical stability, and survived sterilization and prolonged soaking without major changes
in electrochemical properties.
PEDOT-coated and bare electrodes were implanted in the acromiotrapezius muscle of five mice
for muscle signal recording during a period of 6 weeks. The PEDOT coating improved the
electrochemical properties of the stainless steel electrodes, lowering the impedance, which resulted
in enhanced signal to noise ratio during in vivo muscle signal recording compared to bare
electrodes
Using microneedle array electrodes for non-invasive electrophysiological signal acquisition and sensory feedback evoking
Introduction: Bidirectional transmission of information is needed to realize a closed-loop human-machine interaction (HMI), where electrophysiological signals are recorded for man-machine control and electrical stimulations are used for machine-man feedback. As a neural interface (NI) connecting man and machine, electrodes play an important role in HMI and their characteristics are critical for information transmission.Methods: In this work, we fabricated a kind of microneedle array electrodes (MAEs) by using a magnetization-induced self-assembly method, where microneedles with a length of 500â600 Όm and a tip diameter of âŒ20 Όm were constructed on flexible substrates. Part of the needle length could penetrate through the subjectsâ stratum corneum and reach the epidermis, but not touch the dermis, establishing a safe and direct communication pathway between external electrical circuit and internal peripheral nervous system.Results: The MAEs showed significantly lower and more stable electrode-skin interface impedance than the metal-based flat array electrodes (FAEs) in various testing scenarios, demonstrating their promising impedance characteristics. With the stable microneedle structure, MAEs exhibited an average SNR of EMG that is more than 30% higher than FAEs, and a motion-intention classification accuracy that is 10% higher than FAEs. The successful sensation evoking demonstrated the feasibility of the MAE-based electrical stimulation for sensory feedback, where a variety of natural and intuitive feelings were generated in the subjects and thereafter objectively verified through EEG analysis.Discussion: This work confirms the application potential of MAEs working as an effective NI, in both electrophysiological recording and electrical stimulation, which may provide a technique support for the development of HMI
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