From what we can parse in the abstract of the journal The Royal Society of Chemistry, it's a proof-of-concept that's in early development, and still a long way from showing up in your local Apple store.
This is where we laypeople with liberal arts degrees get lost in the jargon-loaded world of science writers. Help us out and translate into English if any of this makes sense to you:
In this compact and cost-effective design attached to a cellphone, we utilize anti-E. coli O157:H7 antibody functionalized glass capillaries as solid substrates to perform quantum-dot-based sandwich assay for specific detection of E. coli O157:H7 in liquid samples. Using battery-powered inexpensive light-emitting-diodes (LEDs) we excite/pump these labelled E. coli particles captured on the capillary surface, where the emission from the quantum dots is then imaged using the cellphone camera unit through an additional lens that is inserted between the capillary and the cellphone. By quantifying the fluorescent light emission from each capillary tube, the concentration of E. coli in the sample is determined. We experimentally confirmed the detection limit of this cellphone based fluorescent imaging and sensing platform as ~5-10 cfu/mL in buffer solution.
Huh, what? We are genuinely awestruck at the brainpower behind this potentially life-saving device, but as lit majors, we pray that the product will come with a user's manual with lots of pictures, fewer words and a point-and-shoot app to let us know if the ribeye in our fridge has gone south or not.