May 23, 2013

CHAMPAIGN, Ill. — Researchers and physicians in the field could soon run  on-the-spot tests for environmental toxins, medical diagnostics, food safety  and more with their smartphones.

University of Illinois at Urbana-Champaign researchers  have developed a cradle and app for the iPhone that uses the phone’s built-in  camera and processing power as a biosensor to detect toxins, proteins,  bacteria, viruses and other molecules.

Having such sensitive biosensing capabilities in the field  could enable on-the-spot tracking of groundwater contamination, combine the  phone’s GPS data with biosensing data to map the spread of pathogens, or  provide immediate and inexpensive medical diagnostic tests in field clinics or  contaminant checks in the food processing and distribution chain.

“We’re interested in biodetection that needs to be  performed outside of the laboratory,” said team leader Brian Cunningham, a  professor of electrical and computer engineering and of bioengineering at the  U. of I. “Smartphones are making a big impact on our society – the way we get  our information, the way we communicate. And they have really powerful  computing capability and imaging. A lot of medical conditions might be  monitored very inexpensively and non-invasively using mobile platforms like  phones. They can detect molecular things, like pathogens, disease biomarkers or  DNA, things that are currently only done in big diagnostic labs with lots of  expense and large volumes of blood.”

The wedge-shaped cradle contains a series of optical  components – lenses and filters – found in much larger and more expensive  laboratory devices. The cradle holds the phone’s camera in alignment with the  optical components.

At the heart of the biosensor is a photonic crystal. A  photonic crystal is like a mirror that only reflects one wavelength of light  while the rest of the spectrum passes through.   When anything biological attaches to the photonic crystal – such as  protein, cells, pathogens or DNA – the reflected color will shift from a  shorter wavelength to a longer wavelength.

For the handheld iPhone biosensor, a normal microscope  slide is coated with the photonic material. The slide is primed to react to a  specific target molecule. The photonic crystal slide is inserted into a slot on  the cradle and the spectrum measured. Its reflecting wavelength shows up as a  black gap in the spectrum. After exposure to the test sample, the spectrum is  re-measured. The degree of shift in the reflected wavelength tells the app how  much of the target molecule is in the sample. See a video of the app in action  at http://www.youtube.com/watch?v=Kh7MUjIYuyw.

The entire test takes only a few minutes; the app walks  the user through the process step by step. Although the cradle holds only about  $200 of optical components, it performs as accurately as a large $50,000  spectrophotometer in the laboratory. So now, the device is not only portable,  but also affordable for fieldwork in developing nations.

In a paper published in the journal Lab on a Chip, the  team demonstrated sensing of an immune system protein, but the slide could be  primed for any type of biological molecule or cell type. The researchers are  working to improve the manufacturing process for the iPhone cradle and are  working on a cradle for Android phones as well. They hope to begin making the  cradles available next year.

 Cunningham’s group is now collaborating with other groups  across campus at the U. of I. to explore applications for the iPhone biosensor.  The group recently received a grant from the National Science Foundation to  expand the range of biological experiments that can be performed with the  phone, in collaboration with Steven Lumetta, a professor of electrical and  computer engineering and of computer science at the U. of I. They are also are  also working with food science and human nutrition professor Juan Andrade to  develop a fast biosensor test for iron deficiency and vitamin A deficiency in  expectant mothers and children.

In addition, Cunningham’s team is working on biosensing  tests that could be performed in the field to detect toxins in harvested corn  and soybeans, and to detect pathogens in food and water.

“It’s our goal to expand the range of biological  experiments that can be performed with a phone and its camera being used as a  spectrometer,” Cunningham said. “In our first paper, we showed the ability to  use a photonic crystal biosensor, but in our NSF grant, we’re creating a  multi-mode biosensor. We’ll use the phone and one cradle to perform four of the  most widely used biosensing assays that are available.”

Cunningham also is affiliated with the Institute for  Genomic Biology, the Beckman Institute for Advanced Science and Technology, and  the Micro and Nanotechnology Laboratory, all at the U. of I.