David Walt of Tufts University constructed a plastic replica of a dogs nasal cavity and installed his fiber-optic-based artificial nose sensors inside. The result was a measurable enhancement in sensitivity. The exercise confirmed a long suspected theory that the anatomy of the nose was an important factor in smell because it results in unique patterns that are easier for the brain to recognize. An article in Nature gives a short overview of the research. More detail on the fiber-optic smell sensor is available on David Walt's website.