Engineers create cell phone-based sensor for detection of E. coli

February 23, 2012 By Wileen Wong Kromhout
Cell phone-based E. coli detector. Image courtesy of UCLA Engineering

( -- Researchers from the UCLA Henry Samueli School of Engineering and Applied Science have developed a new cell phone–based fluorescent imaging and sensing platform that can detect the presence of the bacterium Escherichia coli in food and water. The engineers combined antibody functionalized glass capillaries with quantum dots (semiconductors often used for medical imaging) as signal reporters to specifically detect E. coli particles in liquid samples using a lightweight, compact attachment to an existing cell-phone camera.

Using battery-powered, inexpensive light-emitting diodes (LEDs), the researchers can excite/pump labeled E. coli particles captured on the capillary surface; there, emissions from the quantum dots can be imaged with the cell-phone camera, using an additional lens inserted between the capillary and the cell phone.

The cost-effective cell-phone attachment acts as a florescent microscope, quantifying the emitted light from each capillary after the specific capture of E. coli particles within a sample. By quantifying the florescent light emission from each tube, the concentration of E. coli in the sample can be determined.

E. coli can easily contaminate food and drinking water. It poses a significant threat to public health, even in highly developed parts of the world, and causes a large number of hospitalizations and deaths every year. As few as 10–100 E. coli particles can kill the cells of the intestinal lining, destroy the kidneys and cause blood clots in the brain, as well as seizures, paralysis and respiratory failure.

This study illustrates the promising potential of a –enabled, field-portable and cost-effective E. coli detection platform for the screening of both water and food samples.

Authors of the research include UCLA electrical engineering postdoctoral scholar Hongying Zhu; UCLA electrical engineering undergraduate student Uzair Sikora; and UCLA associate professor of and bioengineering Aydogan Ozcan. Ozcan is also a member of the California NanoSystems Institute at UCLA.

Explore further: Better health through your cell phone

More information: The research is published in the peer-reviewed journal The Royal Society of Chemistry and is available online at

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not rated yet Feb 24, 2012
Another cool but completely useless paper. Strapping a miniature "fluorescent microscope" on the back of a cell phone that relies on its terrible camera is as ridiculous as using a hospital-grade electrocardiogram to measure your heart rate on a treadmill for your workout journal. Lateral flow assays (same thing used in pregnancy tests) for E. Coli cost at most several dollars each, and they're foolproof (you take the strip and dip it in your test solution for a minute or so).

Why would you want to instead deal with using a quantum-dot based sensor that requires you to deal with refilling test solutions, calibrating the microscope, using it somewhere that isn't too bright, keeping the test solutions cold & in the dark, and so on. Makes absolutely no sense. If someone needs to quantify how much E. Coli is present and needs more accuracy than the present-or-not-present results from lateral flow assays, their device of choice isn't going to be a cell-phone based fluorescent scope.
not rated yet Feb 29, 2012
the above is a meaningless comment. if you dip an e coli lateral flow assay on your solution, within a minute you get nothing.
at low concentrations you need to prepare your sample for a few hours at least before a lateral flow assay can be used. otherwise you cannot claim any meaningful sensitivity.

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