Researchers at Purdue University have developed a bioluminescence-sensing assay coupled with a portable light detection device that works with smartphones and laptops to do on-site testing for E. coli in food samples. To facilitate the use of a silicon photomultiplier (SiPM) in a portable, field-deployable device, the researchers designed an electrical circuit consisting of an amplifier, comparator, and microcontroller to send the data from the SiPM to laptops and smartphones via Bluetooth technology. Using 3D printing, they created a portable cradle for housing the SIPM. The SiPM uses low light from the assay to detect the presence of bacteria. Researchers from Purdue created a portable device that works with smartphones and laptops to do on-site testing for E. coli in food samples. Courtesy of Purdue University. The Purdue team tested its device with artificially contaminated samples of ground beef. The researchers incubated beef samples with an engineered luminescent-based bacteriophage and then used the device to analyze the sample within 10 hours of inoculation. When a substrate was added to the bacteria-infected beef, the bacteria emitted light that was detected by the SiPM. A smartphone-based luminometer and a conventional photomultiplier tube-based benchtop luminometer were used to compare detection levels and applicability for supporting luminescent phage-based pathogen detection. The results showed that the SiPM provided better performance in terms of time to detection and signal-to-noise ratio, and could be used as the light detection component of a phage-based detection format. “Our goal is to create technology and a process that allows for the cost-effective detection of the causes of foodborne illness using an easy, expedient, and efficient process,” researcher Euiwon Bae said. “This time-frame allows for better integrated detection and quicker action to stop more people from getting sick.” Bae developed the technology along with Purdue professor Bruce Applegate. “Our assay offers higher sensitivity, lower cost, better portability, and other distinct advantages when compared to existing detection methods,” Applegate said. The phage used with the smartphone technology was developed by Applegate and is being commercialized by Phicrobe, a Purdue University-affiliated startup founded by Applegate. The researchers are working with the Purdue Research Foundation Office of Technology Commercialization to patent the technology and are looking for partners. The research was published in Applied Optics, a publication of The Optical Society (OSA) (www.doi.org/10.1364/AO.59.000801).