Dogs feel their way through the world with their noses. Researchers have started imitating（模仿） this super skill with an artificial-intelligence-based detective tool. In a study published in February in PLOS ONE，a multinational team reported an AI-powered system that is as accurate as trained dogs in correctly recognizing cases of prostate (前列腺) cancer from urine (尿) samples. Andreas Mershin，a research scientist from Massachusetts Institute of Technology, wants to finally integrate the technology into smartphones：There would be a small sensor in the phone with AI software running in the cloud. 

Prostate cancer，the second most deadly cancer in men worldwide，is difficult to detect. The most widely used test can miss 15 percent of cancers. Trained dogs, on the other hand, were able to recognize patients with prostate cancer from urine samples more than 96 percent of the time. Yet dogs can get bored and tired, so researchers want to develop an AI system that works more consistently. 

Living cells produce chemicals that come out from the skin，blood，urine and breath. Artificial noses，including the "Nano Nose" that Mershin and one of his colleagues developed，can already detect those chemicals at the same parts-per-billion concentration as dogs. The team added the chemical sensing to an artificial neural (神经的) network—a type of AI algorithm that can learn from looking at examples how to recognize faces，for instance.

As the 2015 Journal of Urology study showed，dogs can be trained to reach more than 96 percent accuracy，and the AI can be trained to reach that same rate. Mershin plans to train the AI algorithm using data from the "Nano Nose"，which is now one third the size of an iPhone 10 and could be further shrunk to be integrated into smartphones.