title: Severinghaus electrode
text: # Severinghaus electrode
  
  The Severinghaus electrode is an electrode that measures carbon dioxide $(CO_2).$ It was developed by Dr. John W. Severinghaus and his technician A. Freeman Bradley in 1958.
  
  It utilizes a $CO_2-sensitive$ glass electrode in a surrounding film of bicarbonate solution covered by a thin plastic carbon dioxide permeable membrane, but impermeable to water and electrolytic solutes. The carbon dioxide pressure of a sample gas or liquid equilibrates through the membrane and the glass electrode measures the resulting pH of the bicarbonate solution.
  
  Clark, galvanic, and paramagnetic electrodes measure oxygen. Severinghaus electrode measures $CO_2.$ Sanz electrode measures pH.
  
  