Savran, study leader and an associate professor of mechanical engineering at
Purdue University, along with Babak Ziaie, a Purdue University professor of
electrical and computer engineering and biomedical engineering, and a team of
researchers, are developing a low-cost, highly-sensitive biological and chemical sensor that
can detect changes in the pH level of an environment without needing several
sensors being developed today are brilliantly designed but are too expensive to
produce, require highly-skilled operators and are not robust enough to be
practical," said Savran.
new sensor is inexpensive and easy to use while still remaining highly
sensitive. The sensor, which is made of thin stripes of gelatinous hydrogel
that expands and contracts based on the acidity of its environment, can expose
information about different substances in liquid environments by measuring its pH.
diffraction-based sensor uses water-insoluble hydrogel to make a
"diffraction grating," which is a series of raised stripes. These
stripes are coated with gold, and expand and contract based on the pH level of
the environment. The sensors can then analyze laser light, which reflects off
of the cold coating. These reflections from the top of the stripes and the
spaces in between them meddle with one another, which results in a diffraction
pattern that changes based on the height of the stripes.
diffraction patterns show small changes in movement of the hydrogel stripes
when they react to the environment, which ultimately measures pH changes.
precise measurement of pH, the diffraction patterns can reveal a lot of
information about the sample environment," said Savran. "This
technology detects very small changes in the swelling of the diffraction
grating, which makes them very sensitive."
laboratory tests, researchers found that the hydrogel sensor can detect changes less than
one-1,000th on the pH scale. The pH scale typically measures a liquid on a
scale of 0 to 14, where 0 is the most acidic and 14 is the most basic.
know we can make them even more sensitive," said Savran. "By using
different hydrogels, gratings responsive to stimuli other than pH can also be
with any novel platform, more development is needed, but the detection
principle behind this technology is so simple that it wouldn't be difficult to