Over at UMass Amherst, chemist Lili He has come up with a new solution for detecting bacteria on food that doesn’t involve days-long testing periods or expensive equipment. In fact, all you need is a smartphone and a $30 microscope that attaches to the device’s camera.
He’s optical detection method seems pretty easy to use. Take your produce, like raw lettuce or an apple, and run some water off of it, catching it into a container. Place a bacteria-detecting chip in that water, and then view that chip with the microscope attached to your phone. At the moment, any harmful bacteria, like listeria or salmonella, will show up on your phone’s screen as an array of blobby dots. But eventually, He imagines the smartphone doing the detection itself, no human element involved. In other words: take a picture and see.
This is a major improvement over the standard method of bacterial detection, which is called Aerobic Plate Count (APC). APC testing is reliable, but requires all kinds of equipment: pipettes, petri dishes, circulating water baths, agar, an incubator, and equipment for refrigerating and freezing, among others. This new test? Basically none of that.
While He says her test shows both good sensitivity and solid reliability, tests like this are not particularly precise; they show total bacterial counts, rather than singling out the harmful bacteria. The numbers are correlated – a really high general bacteria count indicates that some of it could be harmful – which is why the tests are still useful, but it isn’t laser-focused for pathogens. Still, it amounts to essentially an easy, inexpensive home testing kit, one that could be used both by consumers in their kitchens and by, say, aid workers trying to make sure people don’t get sick.