Metal is the most common electrode material. The type of metal used generally depends upon the application. For instance, lead is a good material for automobile battery electrodes but would be a disaster as a welding rod. Copper, silver, lead and zinc are commonly used metals; however, gold may be used when a high-quality connection is required. The electrode used for the most common type of welding, arc welding, is normally a consumable material compatible with the metal being welded.
Tungsten inert gas (TIG) welding is a special process used for precision welding of thin material. This type welding uses a non-consumable tungsten electrode along with an inert gas. Although the TIG process can be used on all material able to hold a weld, it is normally used to weld stainless steel where precision and quality is very important, such as in aircraft and naval purposes.
Gas diffusion electrodes are used in fuel cells, other electrochemical devices including metal-air batteries, and electrochemical gas sensors. In a fuel cell, hydrogen and oxygen chemically bond to create water at the gas diffusion electrodes. A catalyst is included in the fuel cell to assist with the liquid and gas interaction. This bonding produces electrical energy and the gas diffusion electrode offers optimum conductivity for electron flow
Glass electrodes can be used as special type of lab probes for pH measurements and to determine the concentration of various ions, such as lithium, sodium and ammonium. A standard glass electrode has a glass bulb with a concentration of hydrogen ions on the outer surface. When the probe is submerged in a sample solution with a reference electrode, the change in potential of the glass bulb is proportional to the pH of the solution.
Electromyogram signals are electrical currents produced by the exchange of ions across muscle fiber membranes. EMG electrodes are applied directly to the skin surface or within the muscle to carry the signal to a measuring instrument. This type electrode is essential for electrocardiograms as well as other medical diagnostic processes as it is noninvasive and low-risk.