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Difference between revisions of "Electromyography"
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(Created page with "{{ArtBy| | autore= Enrico Maria Staderini | autore2= Gianni Frisardi }} <br /> ==General Information== A signal is, by definition, nothing more than the graphical representation of the temporal trend of a physical quantity. In the case of the surface electromyogram (sEMG), this quantity is the potential difference generated by the muscle during its contraction, which produces an electric current in the tissues and a potential difference that is ultimately recorded on th...") |
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File:SnapShot 241014 165659. | File:SnapShot 241014 165659.jpg|'''Figure 1:''' Schematic diagram of the transformation of an ion current (negatively charged) into an electron current (negatively charged) through the exploitation of the redox reaction made possible by the presence of the electrode. | ||
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This is precisely the potential difference between the two muscle areas under electrodes A and B. As can be seen from the formula, the common-mode signal has disappeared in the final equation, meaning it could have been anything, assuming that the common-mode voltage between either of the two electrodes A or B and the reference electrode is equal. | This is precisely the potential difference between the two muscle areas under electrodes A and B. As can be seen from the formula, the common-mode signal has disappeared in the final equation, meaning it could have been anything, assuming that the common-mode voltage between either of the two electrodes A or B and the reference electrode is equal. | ||
[[File:Riferimento 2.jpg|left|thumb|'''Figure | [[File:Riferimento 2.jpg|left|thumb|'''Figure 3:''' Electrode placement as discussed in the text]] | ||
Indeed, because of the difference between the signals of the two amplifiers in the differential amplifier, it is not necessary to place the third electrode exactly on the leg. It could be placed anywhere. Not surprisingly, this electrode is often called the "indifferent" electrode because it can be "indifferently" placed anywhere on the body surface. It is also called "ground" or "earth" or "reference," but in the sense of being the reference for the differential amplifier. It is more of a technical, electronic issue than a bioelectric one. In electrocardiographic (ECG) recordings, the indifferent electrode is the "right leg" electrode.<ref>M J Burke 1, D T Gleeson. [https://pubmed.ncbi.nlm.nih.gov/10721622/ A micropower dry-electrode ECG preamplifier] . IEEE Trans Biomed Eng. 2000 Feb;47(2):155-62. doi: 10.1109/10.821734.<br /></ref> | Indeed, because of the difference between the signals of the two amplifiers in the differential amplifier, it is not necessary to place the third electrode exactly on the leg. It could be placed anywhere. Not surprisingly, this electrode is often called the "indifferent" electrode because it can be "indifferently" placed anywhere on the body surface. It is also called "ground" or "earth" or "reference," but in the sense of being the reference for the differential amplifier. It is more of a technical, electronic issue than a bioelectric one. In electrocardiographic (ECG) recordings, the indifferent electrode is the "right leg" electrode.<ref>M J Burke 1, D T Gleeson. [https://pubmed.ncbi.nlm.nih.gov/10721622/ A micropower dry-electrode ECG preamplifier] . IEEE Trans Biomed Eng. 2000 Feb;47(2):155-62. doi: 10.1109/10.821734.<br /></ref> | ||