An array of sensor elements is formed by the incorporation of sensing materials into porous structures, creating sensing systems with extremely large surface areas with sensing molecules attached to mimic the large number of cilia of an olfactory system. In each sensor element, the sensing material or molecules are attached to spacer molecules or groups, which are attached to linker molecules or groups, which are attached to the porous substrate material. More specifically, a porphyrin doped aerogel material is used. The porphyrin sensing material is attached to the aerogel throughout its high surface area pore space. The porphyrin is covalently bonded to the silica network of the aerogel with a triethoxysilyl group linker that covalently attaches to the aerogel, and an alkyl group spacer.