These days surgeons operating on tumors have to wait for the tissue to be analyzed by a lab before they can know if the tissue is healthy or not. But all that could change if a new surgical knife becomes widely available. The knife, invented by Zoltan Takats of Imperial College London, is hooked up to a mass spectrometer that analyzes the smoke that occurs when the tissue is cauterized. The knife picks up the smoke and then compares it with a catalog of smoke signatures of cancerous and noncancerous tissues. The machine costs about $380,000 to make, but that price would likely come down if it were to be commercially manufactured.