I've only suffered through a bad bout of food poisoning once, and, without going into details, I spent one evening of my life knowing I wouldn't wish it on my worst enemies. Apparently I'm lucky, since one in six Americans (or 48 million people) get foodborne illnesses every year, according to the Centers for Disease Control and Prevention. And of the 128,000 who end up hospitalized, 3,000 die.
While 3,000 is a tiny fraction of the 48 million who get sick, better sensors and sensing systems could reduce that number even further. So doctoral student Yating Chai of Auburn University has been working with a team of engineers on a new approach to detecting pathogenic bacteria -- including salmonella and listeria -- in real time.
Unlike traditional methods, which require 48 to 72 hours and involve taking a sample of food, getting the sample to grow, and testing the growth, the Auburn system employs something called a magnetoelastic biosensor. The sensor, which has been studied for several years now, is based on a wireless acoustic wave sensor platform, which is a fancy way of saying that it vibrates at a very specific resonance. When a bacterium attaches itself to the sensor, the change in mass causes the sensor's resonant frequency to change accordingly.
Also unlike traditional methods, which require that the sensor live inside a coil, the Auburn team designed a "microfabricated reading device," says study coauthor Bryan A. Chin, a materials engineering professor at Auburn. This means that the biosensor measurements can be made outside the coil -- in, say, a handheld device that simply passes over food to look for pathogens.
"Now you can put the sensor on the surface of, say, a watermelon," Chin explains. "[In the past], to measure it you'd have to put the whole watermelon inside the coil. Now...you can have this detector waved over the watermelon."
The researchers have filed a patent for their biosensing system. While it's too early to say what it would cost or when it will be market-ready, Chin calls the real-time detector a "major advancement."