**7. Conclusion**

Modification and functionalization of CNTs have shown to greatly improve the sensitivity and selectivity of CNTs-based sensors. For instance, great improvements for room tempera‐ ture detection of different gases have been reported, especially when using metal oxide/ SWCNTs composites. Another subject of high interest is the development of deposition methods and synthesis of Pd/CNTs for H2 detection at room temperature. Interestingly, there is an increase in the tendency of combining other materials with modified CNTs. For example, CNTs decorated with metal NPs embedded in a polymer matrix or CNTs doped or CNTs doped with heteroatoms and decorated with NPs or metal oxides are some compo‐ sites that have been successfully used as gas sensing materials. But not only the characteris‐ tics of the CNTs have contributed to these improvements. In fact, the reported improvements are attributed to the combination of materials and the intrinsic characteristics of the composites. This trend of combining materials demonstrates that the there is broad range of possibilities for the design of new materials to meet the requirements of an ideal sensor by showing selectivity for different gases, sensitivity at low concentrations, fast re‐ sponse, and room temperature operation among others.
