The electrolytic detector, or liquid barretter, was a type of detector (demodulator) used in early radio receivers. First used by Canadian radio researcher Reginald Fessenden in 1903, it was used until about 1913, after which it was superseded by crystal detectors and vacuum tube detectors such as the Fleming valve and Audion (triode).[1][2] It was considered very sensitive and reliable compared to other detectors available at the time such as the magnetic detector and the coherer.[3] It was one of the first rectifying detectors, able to receive AM (sound) transmissions.