Imagine holding your smartphone up to the sky and detecting pollen in the air or bacteria in the water. It's like SpectraSnapp for the living world.
University of Illinois at Urbana-Champaign researchers developed the handheld hardware and smartphone app that transforms the camera and computing capabilities of the iPhone into a sensitive biosensor. The researchers envision scientists, physicians, or even backpackers will be able to use the App, the iPhone GPS software, and holder for in situ air pollution analysis, to find clean groundwater, or to inexpensively and quickly detect toxins, viruses and bacteria at field clinics. The research was published on April 3, 2014 in the journal Lab on a Chip.
The crux of the work lies in the powerful combination of spectroscopy hardware and app software development.
The hardware holds the optical components not found in ordinary smartphones. Released from the binds of optics tables in dark labs, the handheld cradle aligns the lenses and filters with the smartphone's camera.
The secret players in the hardware are specially prepared microscope slides and a photonic crystal that can be designed to reflect one color of light, and allows all the others to pass through. Using different microscope slides prepared react to different biological agents, the researchers coat the slides with a photonic crystal. If a biological agent attaches to the surface of the photonic crystal, the color of light reflected off of the slide will shift towards the red.
To test for a specific biological agent, like E. coli on a spinach packaging plant, the user would slip an "Test-for-E. coli" slide into the cradle and compare the light spectrum when the smartphone is pointed at the spinach to the control spectrum. The degree to which the color of reflected light shifts (which appears as the movement of the black bar in the light spectrum) indicates the amount of E.coli is in the sample.
In the paper, the team tested their design by detecting immune system protein. In theory, the microscope slide could be prepared to detect any biological molecule or cell. The cradle holds only about $200 of optical equipment but provides data comparable with laboratory spectrophotometers hundreds of times the cost. The researchers hope the device will prove effective for on-location analysis in developing countries and hope to make the hardware cradles available next year.