Foodborne illness hits about one in six people in the United States every year from more than 31 recognized pathogens including E. coli O157:H7, a particularly harsh strain of E. coli. Researchers have developed a bioluminescence-based assay coupled with a portable device that works with smartphones and laptops to do on-site testing for harmful E. coli in food samples.
The silicon photomultiplier (SiPM) device uses low light from the bioluminescent assay to detect the presence of bacteria that cause foodborne illness in food samples. They also created an electrical circuit with an amplifier, comparator, and microcontroller to send the data to laptops and smartphones via Bluetooth technology. They used 3D printing to design a portable cradle for the SiPM.
To show the proof of concept, the team tested the device with artificially contaminated samples of ground beef from a local grocery store. They injected E. coh into the beef samples and then used the device to analyze the sample within 10 hours of inoculation. The beef is rinsed and incubated with an enrichment liquid containing a modified phage, a virus for bacteria. The phage then infects harmful foodborne bacteria so that when a substrate is added, the bacteria emit light, which is detected by the SiPM. The device is able to count light pulses or photons.