Innovative Spirit

This Device Tracks How Well You Wash Your Hands

Biomedical engineers have developed a wall-mounted scanner that can detect microbes that cause foodborne illness

The hand dryer-sized device can detect E. coli, salmonella, norovirus, hepatitis A, and listeria. (PathSpot)
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Today, the epitome of foodborne illness prevention technology in commercial kitchens is a sign in the restroom that says “employees must wash their hands before returning to work.” To Christine Schindler and Dutch Waanders, that didn’t seem like the optimal solution.

“We thought, that’s crazy, there should be something that scans peoples hands to see if there’s any foodborne illness,” says Schindler. “We were just asking restaurants what they thought, and when people were saying that they’ve been waiting 10 years for a product like this, that’s when we left our jobs.”

Schindler and Waanders, who both studied biomedical engineering at Duke University, started researching foodborne illnesses, and incorporated PathSpot last year, placing test devices in restaurants starting in January. The foundation of the technology is a type of spectroscopy, says Schindler, who also has a background in global and public health. Proprietary wavelengths put out by a tablet, bounce off of microbes on a person’s hand, and the reflection is received by the tablet’s camera. The light reflects slightly differently based on the shape of whatever it bounces off of, including bacteria. Within a couple of seconds, an algorithm compares the wavelengths of reflected light to the signature of E. coli, salmonella, norovirus, hepatitis A, and listeria, and gives an indication — red or green — of the presence or absence of contaminants. The hand dryer-sized device mounts on the wall next to a sink.

We’re notoriously bad at washing our hands effectively, according to an FDA study released this summer that watched 383 people prepare turkey burgers in test kitchens. Fewer than 3 percent of participants washed their hands for the recommended 20 to 30 seconds, and when researchers analyzed microbe samples from refrigerator handles, spice containers and raw salads, they found up to 41 percent of them had been contaminated. The CDC attributes this sort of behavior in the 48 million sicknesses, 128,000 hospitalizations, and 3,000 deaths from food contamination in the U.S. yearly.

Hand washing failure can be broken into two categories, says Ben Chapman, associate professor and food safety specialist at North Carolina State: efficacy and compliance. Chapman, one of the researchers on the FDA study, is quick to point out that the study tested consumer behavior — people cooking in home kitchens — not commercial food handlers, who are held to hand washing standards by law, not just by recommendation. Furthermore, the study, which is taking place over five years, hasn’t yet differentiated between efficacy and compliance. Someone who skipped a wash after handling poultry but before handling lettuce (a compliance failure) and someone who washed insufficiently (an efficacy failure) both register as failing to wash appropriately, but only one of those people would be caught by a device like PathSpot.

“We don’t really have a great understanding of how compliant food handlers are, with the law,” says Chapman. “The best way we’ve measured it is through routine inspections.”

And while PathSpot considers efficacy the bigger issue, to Chapman it’s compliance. It’s not so much that people fail to wash their hands before food prep or after using the restroom, he says. Rather, they’re unaware of the washing that needs to take place in between the steps of food preparation, like when they alternate handling raw and ready-to-eat food, or they skip washes because they feel they don’t have time. In a 2010 study in the Journal of Food Protection, Chapman put video cameras in restaurant kitchens to observe hand washing practices, and found that workers washed their hands more often and contaminated food less when food safety info sheets were placed in kitchens. To some degree, that washing is obviated by industry practices, he says — many fast food restaurants, for example, use tongs or other easily sterilized tools to handle food, skipping the handling altogether.

Still, a clear yes/no answer to whether employees washed their hands well enough could be valuable, both as a preventive tool and a feedback system to improve employee practices. In a pilot program in 20 locations in Detroit, New York City and Durham, North Carolina, PathSpot saw contamination rates decrease by 60 percent over a month, according to Schindler. And the company saw managers use information on when, where and how hand washing could be improved.

“We’re also able to tell where the most frequent cause of contamination is, so that when they’re customizing training for the establishment they can say hey, we’ve noticed that in a week of hand scanning, we see the biggest issues during the lunch shift and under your right pinky,” says Schindler. “We really try to make the technology something that’s … creating this positive culture of sanitation.”

PathSpot just closed a $2 million round of seed funding. The company has applied for a patent, and it plans to focus on making the devices affordable and placing them in locations that need them. But Schindler believes that won’t be their end game. She envisions similar technology that could detect peanut oil in schools, flu in the workplace, or staph in hospitals.

“The thing that we really care about with this product is the ability for it to grow far beyond detecting foodborne illness on hands to a system for instantaneous detection of illness at large,” says Schindler.

About Nathan Hurst

Nathan Hurst blends a love of storytelling with a passion for science and the outdoors, covering technology, the environment, and much more. His work has appeared in a variety of publications, including Wired, Outside, Make: and Smithsonian.

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