"Blindfolded would you know the smell of your mom a lover or a coworker Not the smells of their colognes or perfumes not of the laundry detergents they use  the smells of them Each of us has a unique odorprint made up of thousands of organic compounds. These molecules offer a whiff of who we are revealing age genetics lifestyle hometown  even metabolic processes that underlie our health. Ancient Greek and Chinese medical practitioners used a patients scent to make diagnoses. Modern medical research too confirms that the smell of someones skin breath and bodily fluids can be suggestive of illness. The breath of diabetics sometimes smells of rotten apples https experts report the skin of typhoid patients like baking bread httpsjamanetwork.comjournalsjamadermatologyarticleabstract. But not every physicians nose is a precision instrument and dogs https while adept at sniffing out cancer get distracted. So researchers have been trying for decades to figure out how to build an inexpensive odor sensor for quick reliable and noninvasive diagnoses. The field finally seems on the cusp of succeeding. Youre seeing a convergence of technology now so we can actually run largescale clinical studies to get the data to prove odor analysis has real utility said Billy Boyle cofounder and president of operations at Owlstone http a manufacturer of chemical sensors in Cambridge England. Mr. Boyle an electronics engineer formed the company with two friends in  to develop sensors to detect chemical weapons and explosives for customers including the United States government. But when Mr. Boyles girlfriend and eventual wife Kate Gross was diagnosed with colon cancer in  his focus shifted to medical sensors with an emphasis on cancer detection. Ms. Gross died at the end of . That she might still be alive if her cancer had been detected earlier Mr. Boyle said continues to be a big motivator. Owlstone has raised . million to put its odor analysis technology into the hands of clinicians. Moreover Britains National Health Service is funding a subject clinical trial httpsclinicaltrials.govctshowNCT to test Owlstones sensor to diagnose lung cancer. The sensor is a silicon chip stacked with various metal layers and tiny gold electrodes. While it looks like your mobile phones SIM card it works like a chemical filter. Editors Picks  The molecules in an odor sample are first ionized  given a charge  and then an electric current is used to move only chemicals of diagnostic interest through the channels etched in the chip where they can be detected. You can program what you want to sniff out just by changing the software Mr. Boyle said. We can use the device for our own trials on colorectal cancer but it can also be used by our partners to look for other things like irritable bowel disease. The company also is conducting a subject trial in collaboration with the University of Warwick to detect colon cancer from urine samples and is exploring whether its chips can help determine the best drugs for asthma patients by sorting through molecules in their breath. A similar diagnostic technology is being developed by an Israeli chemical engineer Hossam Haick who was also touched by cancer. My college roommate had leukemia and it made me want to see whether a sensor could be used for treatment said Mr. Haick a professor at TechnionIsrael Institute of Technology http in Haifa. But then I realized early diagnosis could be as important as treatment itself. His smelling machine uses an array of sensors composed of gold nanoparticles or carbon nanotubes. They are coated with ligands molecular receptors that have a high affinity for certain biomarkers of disease found in exhaled breath. Once these biomarkers latch onto the ligands the nanoparticles and nanotubes swell or shrink changing how long it takes for an electrical charge to pass between them. This gain or loss in conductivity is translated into a diagnosis. Sign up for Science Times Well bring you stories that capture the wonders of the human body nature and the cosmos.  We send all the signals to a computer and it will translate the odor into a signature that connects it to the disease we exposed to it Mr. Haick said. With artificial intelligence he said the machine becomes better at diagnosing with each exposure. Rather than detecting specific molecules that suggest disease however Mr. Haicks machine sniffs out the overall chemical stew that makes up an odor. Its analogous to smelling an orange Your brain doesnt distinguish among the chemicals that make up that odor. Instead you smell the totality and your brain recognizes all of it as an orange. Mr. Haick and his colleagues published a paper in ACS Nano httppubs.acs.orgdoiabs.acsnano.b last December showing that his artificially intelligent nanoarray could distinguish among  different diseases with up to  percent accuracy. There were a total of  participants in the trial but the sample sizes for each disease were quite small. And the machine was better at distinguishing among some diseases than others. In the United States a team of researchers from the Monell Chemical Senses Center https and the University of Pennsylvania received an  grant https_releasesmonell_center_grant_ovarian_cancer_odor_diagnostic in February from the Kleberg Foundation to advance work on a prototype odor sensor that detects ovarian cancer in samples of blood plasma. The team chose plasma because it is somewhat less likely than breath or urine to be corrupted by confounding factors like diet or environmental chemicals including cleaning products or pollution. Instead of ligands their sensors rely on snippets of singlestrand DNA to do the work of latching onto odor particles. We are trying to make the device work the way we understand mammalian olfaction works said Charlie Johnson director of the NanoBio Interface Center http at the University of Pennsylvania who is leading the fabrication effort. DNA gives unique characteristics for this process. In addition to these groups teams in Austria Switzerland and Japan also are developing odor sensors to diagnose disease. I think the fact that youre seeing so much activity both in commercial and academic settings shows that were getting a lot closer said Cristina Davis a biomedical engineer and professor at the University of California Davis who also is helping to develop an odor sensor to diagnose disease. My estimate is its a three to fiveyear time frame before such tools are available to clinicians she added. The researchers may be competing intensely but all see possibilities for saving lives. Theres a lot of good work going on out there Mr. Johnson said. It will be interesting to see who comes out on top. Correction May   An earlier version of this article misstated when Kate Gross died. It was Dec.   not last year. Correction May   An article on Tuesday about odor detection to diagnose disease misspelled the name of a foundation that awarded a grant to advance work on a prototype odor sensor that detects ovarian cancer in samples of blood plasma. It is the Kleberg Foundation not Kleburg."