What’s lurking in your meat and milk and spinach? Food may look safe to eat. But a quick check can’t tell you if your meal is dangerous. Of all the adaptations that humans have been given—smell, taste, disgust—detecting microscopic pathogens isn’t one of them. (And truth be told, since neither the industry nor government want to take responsibility, the onus tends to be on you.) And when unwitting eaters do get sick, an infectious bacterium takes time for experts to identify, more time to confirm, and then it takes the government even more time to issue recalls.
Aydogan Ozcan believes rapid field diagnoses could speed up response time and, in the long-term, lead to better policies. To that end, he’s developed an instant, portable scanner that requires a common technology found in the pockets of about 70% of the population: cell phones. An eight-megapixel camera is more than capable of microscopy. Ozcan, an electrical engineer at University of California, Los Angeles, created a mobile imaging device with comparable resolution to bench microscopes, so cell phones can identify living cells. The first prototypes identified tuberculosis and malaria cells in blood tests. Now, as he shows in research published in Analyst, he recently expanded the phone’s reach so it now works as a pathogenic E. coli detector.
Here’s how to run a sample: First, attach a Sony Ericsson phone to a portable "microscope," a device that looks more like a manual credit-card reader crossed with an optical flatbed scanner. Next, pump contaminated nonfat milk through 10 tiny, glass microcapillaries in the scope. These tubes have been treated with anti-E. coli antibodies so that pathogens in the milk stick to the walls of the micro-straws. Then, it’s time for the lights and the camera. Flip on LED lights and shine ultraviolet light through the tubes—and into the phone’s camera. Tiny luminescent nanocrystals called quantum dots will reflect bright red, sort of like a stained cell on a microscope slide. Count this reflected light with an open-source imaging software developed by the National Institutes of Health called ImageJ and you’ve caught the bad bug red-handed. See: simple.
Food inspectors could encode measurements and also upload data to central servers, Ozcan says, and from there, epidemiologists—the people who study outbreaks—could track a pathogen as it creeps across the nation or even the globe. "It will enable us to look back and understand how certain infectious diseases spread and say what policies work and which do not: Tools like this help us understand and also to say, ‘What’s going on at a larger scale?'"
So far, the detector works with E. coli and salmonella. As a platform technology, it could be expanded to test for other pathogens, maybe for ones that don’t even exist yet, an important adaptation given the multiplicity of pathogens. The Los Angeles startup Holomic licensed the patents and Ozcan expects mobile detectors, at $20 to $30 a piece, to be in our hands by 2014.
So far, Ozcan says he hasn’t mounted any of the prototypes to his fridge. What milk he drinks, he says he takes at the corner coffee shop. "They would refuse to serve me if I did a field test every time," he says. "I should be careful." If mobile inspections can stem the rapid evolution of food-borne pathogens, perhaps he won’t have to be. And if food safety doesn’t fall to consumer advocates, or a single research scientist at the latte counter, his tool might offer another route to protect us against pathogens: by preventing them in the first place.