More specifically, the 3D-printed chip hosts an array of optical adaptamer-based sensors with a 3D stop-valve mechanism, which facilitates the automatic flow of food samples into the chip for detection purposes. Adaptamers are molecules of artificial single-stranded DNA, RNA, or peptides that bind other target molecules. The adaptamers are integrated into anodic alumina oxide (AAO) which makes up the chip, and which has unique optical and electrochemical properties that can be utilized to convert binding events into measurable signals. The nanoporous structure of AAO also facilitates rapid diffusion of analytes, speeding up reaction kinetics and reducing detection times.

When tested against a series of concentrations of S. aureus, Salmonella typhimurium, L. monocytogenes, and E. coli in a buffer solution, the sensor was able to detect the pathogens at levels as low as 10 colony forming units per milliliter (CFU/ml). The optical sensor could also easily detect foodborne pathogens above 100 CFU/ml.

Overall, the researchers are confident in the sensitivity and specificity of their sensor. Being 3D-printed, the chip could be reproduced easily and cost-effectively. The researchers plan to continue developing the device to optimize it for real-world foodborne pathogen detection.