Fig. 3From: Fabrication and characterization of VOC sensor array based on SnO2 and ZnO nanoparticles functionalized by metalloporphyrinsa Optical image of the fabricated sensor platform. Scanning electron microscope image of b ZnO NPs/CoPP, c SnO2 NPs/CoPP, d SnO2 NPs/ZnPP, and e SnO2 NPs/NiPPBack to article page