Smartphone App to act as Cheap Disease Detecting Device
Researchers have
developed a new smartphone app that uses the mobile's built-in camera and
processing power as a biosensor to detect toxins, proteins, bacteria, viruses
and other molecules.The app and cradle system for smartphones has sensitive
biosensing capabilities that could enable on-the-spot tracking of groundwater
contamination and combine the phone's GPS data with biosensing data to map the
spread of pathogens.
The system could
provide immediate and inexpensive medical diagnostic tests in field clinics or
contaminant checks in the food processing and distribution chain, researchers
at University of Illinois at Urbana-Champaign said.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 colour will shift from a shorter wavelength to
a longer wavelength. For the handheld 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. 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 USD 200 of optical
components, it performs as accurately as a large USD 50,000 spectrophotometer
in the laboratory. So now, the device is not only portable, but also affordable
for fieldwork in developing nations. In the study, 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.
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