Gas sensor element

A gas sensor element comprising:

• a detection portion having a stack of a solid electrolyte body and a heat generating body, the solid electrolyte body having at least a pair of electrodes on opposite sides thereof and the heat generating body including a heat generating source;
• and
• a porous protective layer formed around the detection portion, wherein
• the porous protective layer has a thermal conductivity λ in a range of 0.2 to 5 W/mK, and has λCpρ in a range of 5.3×105 to 2.1×107 WJ/m4K2, the λCpρ being a product of the thermal conductivity λ(W/mK), density ρ(g/m3), and specific heat Cp(J/gK), and
• the porous protective layer further has a capillary radius in a range of 0.01 to 10 μm.

A gas sensor element comprising:

• a detection portion having of a solid electrolyte body and a heat generating body, the solid electrolyte body having at least a pair of electrodes on opposite sides thereof and the heat generating body including a heat generating source;
• and
• a porous protective layer formed around the detection portion, wherein
• the porous protective layer has a thermal conductivity λ in a range of 0.2 to 5 W/mK, and has λCpρ in a range of 5.3×105 to 2.1×107WJ/m4K2, the λCpρ being a product of the thermal conduct λ(W/mK), density ρ(g/m3), and specific heat Cp(J/gK), and
• the porous protective layer has a single-layer structure including an aggregate and a coating material, the aggregate containing at least one of silicon carbide or aluminum nitride, and the coating material containing at least one of silica or antimony oxide.