The SnO nanoflowers are composed of two main planes; the flat regions (001) planes and the edges (101) planes . These particles aggregate at carbon debris forming a self-assembling SnO nanoflower network between the current collectors, as shown in the SEM micrographs, fig. . Due to their layered aggregate nanoflower structure, the granular network of SnO particles deviates from the typical homogenous surfaces of spherical/rod/wire structures implicitly assumed in MOX chemiresistive sensors. Instead, there are numerous particle junctions. Due to the flower morphology, the particles will interface at planes, rather than (001) planes as the petals block the overlap of (001) planes. Therefore the conduction path is comprised of a series of (101) interfaces and parallel paths through (001) top surfacs and (001) bulk regions. Consequently, the selectivity and degree of interaction of a given analyte will depend on the morphology of the particles used and the relative contributions of these two planes.