[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-657675-105":59,"doc-detail-657675-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","ecg-instrumentation","ECG Instrumentation","","ECG instrumentation describes how ionic potentials generated in the body are converted into measurable electronic signals using electrode transducers. It explains electrode types (polarizable vs non-polarizable), typical limb lead placements and reference ground, and the silver–silver chloride electrode chemistry that forms an electrode double layer. Equivalent R-C(-R) circuit models are used to represent electrode–electrolyte impedance, including effects of electrochemical processes and movement artefacts. It also introduces amplifier needs and key interference from the electrical power system.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/ecg-instrumentation/657675/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/ecg-instrumentation/657675.png","ImageObject",300,407,{"name":92,"@type":93},"Olivia Brown","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-29","2026-10-26",true,{"@type":102,"interactionType":103,"userInteractionCount":81},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"Why are electrodes needed in ECG instrumentation?","Question",{"text":112,"@type":113},"Electrodes convert ionic potentials in the body into electronic potentials that conventional instrumentation can measure, by sensing the ionic potential difference between electrode contact points on the body surface.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How is the silver–silver chloride electrode interface modeled?",{"text":117,"@type":113},"The electrode forms an electrode double layer that introduces a potential drop (half-cell potential). The interface is modeled using an R-C structure, then extended by adding a parallel resistance to represent electrochemical processes.",{"name":119,"@type":110,"acceptedAnswer":120},"What causes movement artefacts in ECG measurements?",{"text":121,"@type":113},"When an electrode moves relative to the electrolyte, it disturbs the charge distribution at the interface and temporarily changes the half-cell potential, creating a potential difference that interferes with ECG signals.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},657675,1793081736,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":81,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":52,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144},16904993612988,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","ECG Instrumentation  \nIn order to record the ECG, we need a transducer capable of converting the ionic potentials generated within the body into electronic potentials which can be measured by conventional electronic instrumentation. Such a transducer consists of a pair of electrodes, which measure the ionic potential difference between their respective points of application on the body surface. Electrodes may be classified either as polarisable, in which case they behave as capacitors, or non −polarisable, in which case they behave as resistors. Common electrodes have characteristics that lie between these extremes; the silver − silver chloride electrode discussed below approximates more closely to a non −polarisable electrode.  \nEquivalent circuit of a system for recording the ECG Electrode placement  \nThe most obvious way to record the ECG is between the Right Arm (RA) and the Left Arm (LA) although another two combinations using the Left Leg (LL) are also used clinically (RA−LL and LA−LL) . Figure 9 summarises this.  \nVI = (potential at LA) − (potential at RA)  \nVII = (potential at LL) − (potential at RA)  \nVIII = (potential at LL) − (potential at LA)  \nFigure 9: Typical electrode placement  \nAnother electrode is also used to connect the patient to the common ground of the instrumentation. Usually, this ground electrode is attached to the right leg.  \nSilver− silver chloride electrode  \nElectrodes for recording biopotentials are composed of a metal (usually silver for ECG measurement), and a salt of the metal (usually silver chloride) . In addition, some form of electrode paste or jelly is applied between the electrode (normally a flat silver disc) and the skin. The combination of the ionic electrode paste and the silver metal of the electrode forms a local solution of the metal in the paste at the electrode − skin interface (also referred to asthe electrode−tissue or electrode − electrolyte interface) . Hence, some of the silver dissolves into solution producing Ag+ ions:  \n􀀀 ✁ ✂ ✄ ☎ ✆ ✝ ✞ ✝✁ ☎ ✟ ✠ ✡ ☛ ✄ ☎ ☞✌ ✍ ✠ ✎ ✏ ✁ ✄✝ ✑ ✡ ✒☛ ☞ ✁ ☛✂✌ 􀀀 ✄ ☎ ✓ ✆ ✁ ✝✔✆ ☞ ✑ ✁ ✠✔ ✕ ✖ ✖ ✗ ✘ ✆ ✙ ✁ ✚ ✡ ✛ ✜ ✢  \nAg ✣ Ag✤ e !  \nIonic equilibrium takes place when the electric field set up by the dissolving ions is balanced by the forces of the concentration gradient. At this point, there is a monomolecular layer of Ag+ ions at the surface of the electrode and a corresponding layer of Cl− ions adjacent to this. This combination is called the electrode double layer and there is a potential drop E across this layer, called the half − cell potential (0. 8V in the case of the Ag−AgCl electrode) .  \nEquivalent circuit of electrode interface  \nThe double layer of charges of opposite sign separated by a dialectric constitutes a form a capacitance, say C. However, since the Ag−AgCl electrode behaves mostly as a non − polarisable electrode, the main component of the impedance is resistive, say R 1 .  \nElectrode  Body electrolytes  \nC R 1 E  \nFigure 10: Simple R−C model of electrode − electrolyte interface  \nThe series model in Figure 10 needs to be modified to account for the fact that the impedance does not increase to infinity as the frequency tends to zero. This is done by adding a parallel resistance R2 (as shown in Figure 11) which accounts for the electrochemical processes taking place at the electrode − electrolyte interface. The values of R 1 , R2 and C depend on the electrode area, surface condition, current density and the type and concentration of electrode paste used. (Typical values are R 1 = 2kΩ, R2= 10kΩ and C= 10µF.)  \nC  \nElectrode  \nBody electrolytes  \nE  \nR2  \nFigure 11: Equivalent circuit of the Ag−AgCl interface  \nMovement artefact  \nIf the electrode is moved with respect to the elctrolyte, this mechanically disturbs the distribution of charge at the interface and results in a momentary change of the half−cell potential until equilibrium can be re − established. If a pair of electrodes are in contact with an electrolyte and one moves whi","cbCaicopdzWBLZSP","https://ap.wps.com/l/cbCaicopdzWBLZSP","pdf",98144,"English","# ECG Instrumentation\n## Electrode transducers and classification\n## Electrode placement and lead equations\n## Silver–silver chloride electrode interface\n## Equivalent circuit models (R-C and extended models)\n## Movement artefact\n## ECG amplifiers and power-line interference","[{\"question\":\"Why are electrodes needed in ECG instrumentation?\",\"answer\":\"Electrodes convert ionic potentials in the body into electronic potentials that conventional instrumentation can measure, by sensing the ionic potential difference between electrode contact points on the body surface.\"},{\"question\":\"How is the silver–silver chloride electrode interface modeled?\",\"answer\":\"The electrode forms an electrode double layer that introduces a potential drop (half-cell potential). The interface is modeled using an R-C structure, then extended by adding a parallel resistance to represent electrochemical processes.\"},{\"question\":\"What causes movement artefacts in ECG measurements?\",\"answer\":\"When an electrode moves relative to the electrolyte, it disturbs the charge distribution at the interface and temporarily changes the half-cell potential, creating a potential difference that interferes with ECG signals.\"}]","ECG Instrumentation | PDF",1792986185,25]