University of Tokyo Olfactory Sensor
Researchers have long sought a chemical detector that's sensitive enough to discern even the faintest whiff of airborne contaminants such as ammonia and sulfur dioxide. Now University of Tokyo researchers have built one based on one of nature's champion sniffers: insects. The scientists injected unfertilized frog eggs with genes from fruit flies and moths, the olfactory cells of which are highly sensitive to chemicals, and sandwiched the eggs between two electrodes. The cells can be genetically modified to screen for specific molecules in concentrations as low as a few parts per billion, and their ability to distinguish between very similar molecules leads to a low incidence of false positives.