String galvanometer

String galvanometer

The String galvanometer was one of the earliest instruments capable of detecting and recording the very small electrical currents produced by the human heart and provided the first practical Electrocardiogram (ECG). Moving coil galvanometers were not at the time sufficiently sensitive to record the electrical currents involved.

Willem Einthoven solved the problem by producing a very long filament of negligible mass that conducted the electrical currents from the heart. This filament was acted upon by powerful electromagnets, which caused sideways displacement of the filament in proportion to the current carried. The movement in the filament was measured using sensitive optical devices.

The filament was originally made by drawing out a filament of glass from a crucible of molten glass. To produce a sufficiently thin and long filament an arrow was fired across the room so that it dragged the filament from the molten glass. The filament so produced was then coated with silver to provide the conductive pathway for the current. [ [http://books.google.com/books?id=_w9v_ZkzTZoC&pg=PA112&lpg=PA112&dq=string+galvanometer+arrow&source=web&ots=9kIiUHQJcy&sig=nkKW7k_G1DQJlcqOhwmATDy-Wiw#PPA113,M1 A History of Electrocardiography pg 112-113] ]

The original machine required water cooling for the powerful electromagnets, required 5 operators [ [http://www.nia.nih.gov/HealthInformation/Publications/AgingHeartsandArteries/chapter05.htm NIH] ] and weighed some 600 lb. [ [http://chem.ch.huji.ac.il/history/einthoven.html Einthoven (1901)] ]

References


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  • string galvanometer — noun : a galvanometer for measuring oscillating currents by the lateral motions of a silver plated quartz fiber traversed by the current and stretched under adjustable tension perpendicular to the field of an electromagnet …   Useful english dictionary

  • Galvanometer — D Arsonval/Weston galvanometer movement with the moving coil shown in red. A galvanometer is a type of ammeter: an instrument for detecting and measuring electric current. It is an analog electromechanical transducer that produces a rotary… …   Wikipedia

  • Einthoven galvanometer — string galvanometer the original type of electrocardiograph, which consisted of a delicate thread of silvered quartz or platinum stretched between the poles of a strong magnet; the thread is displaced by an electric current flowing through it in… …   Medical dictionary

  • galvanometer — An instrument for measuring the strength of an electric current. d Arsonval g. a sensitive g. consisting of a moving coil suspended in a permanent magnetic field between delicate metallic wires or ribbons that serve as both torsion …   Medical dictionary

  • cord galvanometer — styginis galvanometras statusas T sritis Standartizacija ir metrologija apibrėžtis Galvanometras, kurio judamoji dalis yra laidus siūlas, galintis slinkti tarp nuolatinio magneto arba elektromagneto polių. atitikmenys: angl. cord galvanometer;… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • cord galvanometer — styginis galvanometras statusas T sritis fizika atitikmenys: angl. cord galvanometer; string galvanometer vok. Bändchengalvanometer, n; Fadengalvanometer, n; Saitengalvanometer, n rus. струнный гальванометр, m pranc. galvanomètre à corde, m;… …   Fizikos terminų žodynas

  • Willem Einthoven — Infobox Scientist name = Willem Einthoven image size = 180px caption = Willem Einthoven in 1906 birth date = May 21, 1860 birth place = Semarang death date = September 29, 1927 death place = Leiden, Netherlands nationality = Netherlands field… …   Wikipedia

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