Table 1 The mechanism and characteristics of different types of hydrogen sensors

Chemiresistive

Based on changes of electrical signals (resistances or conductances) when H₂ molecules interact with the sensing materials.

High sensitivity;

Acceptable stability;

Ease of integration^37,49;

Low-cost fabrication.

Poor selectivity;

Many sensors need high operating temperatures⁴⁵⁹.

Electrochemical

Based on changes in charge transfer or electrical properties due to chemical reactions between H₂ and the sensor electrode, where H₂ is oxidized at the anode and O₂ is reduced at the cathode.

Low power consumption;

Good selectivity⁴⁶⁰;

High sensitivity^461,462.

Easy corrosion and difficult packaging for liquid electrolyte;

Susceptible to ambient conditions (oxygen and humidity levels)⁴⁵;

High fabrication costs.

Thermal conductive

Detecting changes in the thermal conductivity of a gas mixture caused by the presence of H₂.

Fast response;

Good stability^463,464;

Low cost.

Low sensitivity⁴⁸;

Susceptible to variations in flow rate and temperature⁴⁶⁵.

Optical

Relying on changes in light intensity upon exposure to H₂.

Improved safety⁵²;

Anti-electromagnetic interference;

High selectivity⁴⁶.

High cost;

Difficult integration into battery production process¹⁶.

Catalytic

Measuring the temperature increase generated by flameless combustion of H₂ on a catalytic surface for the detection of H₂

Low-cost;

Fast response.

Poor selectivity⁴⁷;

High power consumption;

Degradation of catalyst⁴⁶⁶.