Our group studies the olfactory system by investigating theoretical models of the receptors. We would like to understand how the typically complex odors, consisting of various substrates at different concentrations, are processed. Furthermore, some substrates often appear together in odors, for instance because the originate from the same biological process. Clearly, typical odor mixtures also vary from place to place and from season to season. This structure in typical odor mixtures has likely played a role in evolution to optimize the receptors. By studying simple model as well as naturally occurring receptors, we will uncover design principles of the olfactory system, which can then be used to improved artificial smell sensors.