Suppose we use a transition metal oxide to make a sensor:

For the sensor to work, the reactions that need to occur are oxidation to generate electron holes and reduction to generate electrons. It is not unusual for conductivity values to range over $25$ orders of magnitude, from the most insulating material Lif $($band gap $>12eV)$ to superconductors $($no band gap$).$ Ionic conductivity, as exhibited in sensors$,$ electrochemical pumps, and solid electrolytes in fuel cells, involves the movement of ions and electrons.

Measured electrical conductivity $)$ from both ions and electrons:

${}_{\text{t}\text{o}\text{t}\text{a}\text{l}}={}_{\text{e}\text{l}\text{e}\text{c}}+{}_{\text{i}\text{o}\text{n}}$

$t_i=$ transference number $=\frac{{}_i}{{}_{\text{t}\text{o}\text{t}\text{a}\text{l}}}$

If $t_{\text{e}\text{l}\text{e}\text{c}}>t_{\text{i}\text{o}\text{n}}$ it is an electronic conductor.

If $t_{\text{i}\text{o}\text{n}}>t_{\text{e}\text{l}\text{e}\text{c}}$ it is an ionic conductor.

Oxides that are easily reduced are n$-$type semiconductors, e$.$g$.Ti{O}_2,Sn{O}_2,$ZnO,$BaTi{O}_3.$

Oxides that are easily oxidized are p$-$type semiconductors, e$.$g$.$ transition metal monoxides $($NiO$,$ FeO, CoO$).$

Based on these statements, suggest a transition metal oxide that can be used as a sensor$,$ and explain how you would make it work. You can use an appropriate search tool such as web of Science to answer this.