Electrocardiograph

An electrocardiograph is the device used in electrocardiography to produce an electrocardiogram, a line-graph recording of the heart's electrical activity across repeated heartbeats, most commonly abbreviated ECG or EKG. Electrodes placed on the skin detect the minute electrical voltage shifts produced by the heart muscle with each beat, and the device plots those voltage changes over time. The Dutch physiologist Willem Einthoven developed the foundational technology, building a string galvanometer in 1903 sensitive enough to measure the heart's small electrical signals precisely, an achievement recognized with the Nobel Prize in 1924. Electrocardiographs have since moved from analog electronics to devices using analog-to-digital converters, and modern versions range from wheeled hospital carts with screens down to compact fitness trackers and smartwatches.