Smell, it helps remind us when it's time to take out the garbage or change the baby's diaper. We use it to detect danger, such as a gas leak or food burning on the stove. Industries that develop products to help us either smell good or prevent aromatic offense testify to the aesthetic importance of odors, as well as to economic value. Still, olfaction's significance is unparalleled in the animal kingdom, where many species' survival would be jeopardized without the ability to detect and recognize odors. Integrating electronic noses with other sensors on complex, intelligent platforms offers exciting application possibilities and considerable development challenges.