Enlarge Image Sharp thinking. The iKnife sucks surgical smoke into a mass spectrometer, which then indicates whether the cut tissue is cancerous or healthy. Credit: J. Balog et al., Science Translational Medicine (2013) When surgeons can't determine the edges of a tumor, it's a problem. Cut too much, and they risk hurting the patient. Cut too little, and they may leave stray cancer cells behind. Now, researchers have developed a surgical knife that can sniff the smoke made as it cuts tissue, almost instantly detecting whether cells are cancerous or healthy. The souped-up scalpel works by analyzing lipids, the...