Selective noninvasive electrode to study myoelectric signals

Bhullar, H.K.; Loudon, Gareth; Fothergill, J.C.; Jones, N.B.

doi:10.1007/bf02442611

Cited by 18 publications

(3 citation statements)

References 4 publications

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“…The impulse response of a rectangular grid of electrodes cannot be invariant to rotations, regardless of the electrode shapes and weights with which signals are combined . The only isotropic detection systems are the monopolar ones (with circular or point electrodes) and the concentric ring systems (Bhullar et al 1990;Farina and Cescon 2001). Nevertheless, the isotropic condition can be approximated by grids of electrodes resulting in a transfer function which is ''close'' to a function invariant to rotations .…”

Section: A Note On Isotropymentioning

confidence: 99%

Influence of anatomical, physical, and detection-system parameters on surface EMG

Farina

Cescon

Merletti

2002

Biological Cybernetics

317

269

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Many previous studies were focused on the influence of anatomical, physical, and detection-system parameters on recorded surface EMG signals. Most of them were conducted by simulations. Previous EMG models have been limited by simplifications which did not allow simulation of several aspects of the EMG generation and detection systems. We recently proposed a model for fast and accurate simulation of the surface EMG. It characterizes the volume conductor as a non-homogeneous and anisotropic medium, and allows simulation of EMG signals generated by finite-length fibers without approximation of the current-density source. The influence of thickness of the subcutaneous tissue layers, fiber inclination, fiber depth, electrode size and shape, spatial filter transfer function, interelectrode distance, length of the fibers on surface, single-fiber action-potential amplitude, frequency content, and estimated conduction velocity are investigated in this paper. Implications of the results on electrode positioning procedures, spatial filter design, and EMG signal interpretation are discussed.

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Section: A Note On Isotropymentioning

confidence: 99%

Influence of anatomical, physical, and detection-system parameters on surface EMG

Farina

Cescon

Merletti

2002

Biological Cybernetics

317

269

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“…The interference is reduced by using proper cabling to minimize inductive and capacitive coupling, and by careful skin preparation when surface electrodes are used to ensure low skin-electrode impedance (and so increase the strength of the signal before amplification). Active electrodes, which include a pre-amplifier as part of the electrode assembly, also help by amplifying the signal close to the source (BHULLAR et al, 1990). Power line interference is often assumed to be common to a pair of electrodes and will ideally be completely attenuated by a differential amplifier with high common-mode rejection.…”

Section: Introductionmentioning

confidence: 99%

Reducing power line interference in digitised electromyogram recordings by spectrum interpolation

Mewett

Reynolds

Nazeran

2004

Med. Biol. Eng. Comput.

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Interference from power lines (50 or 60 Hz) is the largest source of extraneous noise in many bio-electric signals and is within the bandwidth of many such signals. In this study, two different methods were compared for their efficacy in removing 50 Hz noise added to surface electromyogram (EMG) signals free of power line interference. The first was a simple second-order recursive digital notch filter. The second was an approach called spectrum interpolation, in which it is assumed that the magnitude of the original 50 Hz component of the EMG signal can be approximated by interpolation of the amplitude spectrum of the signal. When the spectrum was based on records containing an integer number of cycles of 50 Hz interference, and the frequency resolution was finer than 1 Hz, spectrum interpolation performed similarly to, or significantly better than, the notch filter (p < 0.01). It was also possible to make spectrum interpolation more robust than the notch filter. The Pearson squared correlation coefficient r2 between clean signals and signals processed using the notch filter was reduced from 0.98 to 0.65 when the interference frequency was increased by 0.5 Hz, but r2 for spectrum interpolation at 0.2 Hz resolution was only reduced from 0.99 to 0.85 if spectral values between approximately 49.5 and 50.5 Hz were modified by interpolation.

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“…In contrast, conventional bipolar derivation requires the alignment of the two electrodes in the myofiber direction, which becomes problematic at muscle boundaries or when assessing muscles with differing myofiber directions [ 16 ]. To address this, the bull’s-eye electrode [ 17 , 18 ], designed for anisotropy-free bipolar derivation, employs a central pin electrode and a concentric ring electrode configuration. This design eliminates the need for electrode-muscle fiber alignment, conductive paste, or gel, making it suitable for wide-area multipoint sEMG measurements.…”

Section: Introductionmentioning

confidence: 99%

Multipoint surface electromyography measurement using bull’s-eye electrodes for wide-area topographic analysis

Shimura,

Mizumoto,

Xia

et al. 2023

J Physiol Anthropol

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Background Surface electromyography (sEMG) is primarily used to analyze individual and neighboring muscle activity. However, using a broader approach can enable simultaneous measurement of multiple muscles, which is essential for understanding muscular coordination. Using the “bull’s-eye electrode,” which allows bipolar derivation without directional dependence, enables wide-area multipoint sEMG measurements. This study aims to establish a multipoint measurement system and demonstrate its effectiveness and evaluates forearm fatigue and created topographic maps during a grasping task. Methods Nine healthy adults with no recent arm injuries or illnesses participated in this study. They performed grasping tasks using their dominant hand, while bull’s-eye electrodes recorded their muscle activity. To validate the effectiveness of the system, we calculated the root mean squares of muscle activity and entropy, an indicator of muscle activity distribution, and compared them over time. Results The entropy analysis demonstrated a significant time-course effect with increased entropy over time, suggesting increased forearm muscle uniformity, which is possibly indicative of fatigue. Topographic maps visually displayed muscle activity, revealing notable intersubject variations. Discussion Bull’s-eye electrodes facilitated the capture of nine homogeneous muscle activity points, enabling the creation of topographic images. The entropy increased progressively, suggesting an adaptive muscle coordination response to fatigue. Despite some limitations, such as inadequate measurement of the forearm muscles’ belly, the system is an unconventional measurement method. Conclusion This study established a robust system for wide-area multipoint sEMG measurements using a bull’s-eye electrode setup. This system effectively evaluates muscle fatigue and provides a comprehensive topographic view of muscle activity. These results mark a significant step towards developing a future multichannel sEMG system with enhanced measurement points and improved wearability. Trial registration This study was approved by the Ethics Committee of Chiba University Graduate School of Engineering (acceptance number: R4-12, Acceptance date: November 04, 2022).

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Selective noninvasive electrode to study myoelectric signals

Cited by 18 publications

References 4 publications

Influence of anatomical, physical, and detection-system parameters on surface EMG

Influence of anatomical, physical, and detection-system parameters on surface EMG

Reducing power line interference in digitised electromyogram recordings by spectrum interpolation

Multipoint surface electromyography measurement using bull’s-eye electrodes for wide-area topographic analysis

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