Simplification of sensor elements

The prototype sensor element in the gas concentration cell needs a reference gas (air or Hj) and is not necessarily suited for simplification and microminiaturization. Elimination of the reference gas flow to change it into a probe type element is highly desirable. Several methods have been proposed for this purpose as follows. 

In the potentiometric sensing of H2, (ii) is useful for H2 in inert gases while (i) is especially suited for H2 in air. On the other hand, only (iii) is applicable to the amperometric sensor and the four-probe type sensor. 

The probe-type elements (without reference gas) thus obtained are convenient for microminiaturization and integration. In fact, several micro sensors have been fabricated by combining proton conductor films and hydride counter electrodes (PdH or TiH ) their good sensing characteristics have been reported For detection of H2 in air, we have reported a potentiometric element (a) and an amperometric element 

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