ABSTRACT
Analytical chemists have done research on, made and used sensors for years. Ion-sensitive and redox- sensitive electrodes have been known and used for 100 years…since the days of Nernst. Membrane-based glass electrodes were invented in 1906; rudimentary ion selective membrane electrodes appeared soon after synthetic, polymer-based ion exchanging materials were invented in 1935. Continuous electrolytic (coulometric) gas analyzers for SO2 were made by 1949. Practical amperometric sensors have been around at least since the Keidel Cell Moisture Monitor (continuous electrolytic water monitor of the 1950s). The Clark amperometric ambient and dissolved oxygen partial pressure sensor has been known, commercialized and adapted to various biochemical and clinical analyses for many years.
