A hydrogen sulfide sensor or H₂S sensor is a gas sensor for the measurement of hydrogen sulfide

Hydrogen sulfide

Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

.

Principle

The H₂S sensor is a metal oxide semiconductor (MOS) sensor which operates by a reversible change in resistance

Electrical resistance

The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

 caused by adsorption

Adsorption

Adsorption is the adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. It differs from absorption, in which a fluid permeates or is dissolved by a liquid or solid...

 and desorption

Desorption

Desorption is a phenomenon whereby a substance is released from or through a surface. The process is the opposite of sorption . This occurs in a system being in the state of sorption equilibrium between bulk phase and an adsorbing surface...

 of hydrogen sulfide in a film with hydrogen sulfide sensitive material like tin oxide

Tin oxide

Tin oxide may refer to:* Tin oxide , SnO* Tin dioxide , SnO2...

 thick films and gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 thin film

Thin film

A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....

s. Current response time is 25 ppb to 10 ppm < one minute.

Applications

This type of sensor has been under constant development because of the toxic and corrosive nature of hydrogen sulfide:

• The H₂S sensor is used to detect hydrogen sulfide in the hydrogen
  Hydrogen
  Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
  
   feed stream of fuel cell
  Fuel cell
  A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used...
  
  s to prevent catalyst poisoning
  Catalyst poisoning
  Catalyst poisoning refers to the effect that a catalyst can be 'poisoned' if it reacts with another compound that bonds chemically to its active surface sites. This effectively reduces the usefulness of the catalyst...
  
   and to measure the quality of guard beds used to remove sulfur from hydrocarbon fuels./-

Research

• 2004 - a nanocrystalline SnO2–Ag
  Silver
  Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
  
   on ceramic wafer
  Wafer (electronics)
  A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
  
   sensor is reported.

See also

• Calibration
  Calibration
  Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....
  
  
• CMOS
  CMOS
  Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...
  
  
• Drift (sensor)
• Glossary of fuel cell terms
  Glossary of fuel cell terms
  The Glossary of fuel cell terms lists the definitions of many terms used within the fuel cell industry. The terms in this fuel cell glossary may be used by fuel cell industry associations, in education material and fuel cell codes and standards to name but a few. –...
  
  
• List of sensors
• Microelectromechanical systems
  Microelectromechanical systems
  Microelectromechanical systems is the technology of very small mechanical devices driven by electricity; it merges at the nano-scale into nanoelectromechanical systems and nanotechnology...
  
  
• Thin film metal oxide semiconductor