HOUGHTON – The dull black plastic of the device on Joshua
Pearce’s desk belies its usefulness. Pearce picks up the box, which has a
switch on the side and a small opening on top. A handful of vials sit in a bag
nearby, and each would fit snugly in the opening. The set-up seems generic,
even bland, except that it could radically change how we deal with water
quality issues.
Pearce, who has a joint appointment as an associate
professor of materials science and engineering as well as electrical and
computer engineering, runs an open sustainability
technology lab at Michigan Technological University. Along with his
students, Pearce made the handheld device with a 3-D printer and open source
hardware in collaboration with the Nitrate Elimination Company, Inc. (NECi).
The small machine replaces comparable devices that cost more and rely on old
methods based on cadmium or zinc. The idea is to create better tools for
testing nitrate content in water and soils. This week,PLOS ONE published the team’s research on the device.
“The beauty of this device is that it’s extremely adaptable,
more sensitive, safer and smaller,” Pearce says. “We have both the ‘business
story’ and the ‘feed the people story’ here.”
Nitrate and Water Quality
High nitrate levels in water cause the dead zones in the
world’s largest deltas. Using too much nitrogen fertilizer wastes resources and
leads to nitrate in runoff and water wells and an excess of nitrate in drinking
water is a health hazard to infants and harmful to many animals. Current
portable nitrate testers range in price and accuracy, from ballpark data at low
price points to several hundred dollars for a handheld photometer. This new
design is palm-sized, interfaces with a free Android app, costs less than $65
to manufacture and uses green chemistry for a safer and more accurate testing
procedure.
“This is a Popeye-approved reagent methodology,” Pearce
jokes, adding that the enzyme used in the test kit is found in spinach and
other leafy greens. “We’re replacing a toxic heavy metal with something that
you eat every day in your salad.”
Kale and collards aside, Pearce is serious about how the
enzyme, called nitrate reductase, makes for a better device since NECi
considers the chemical processing from sourcing to disposal. The PLOS ONE paper
is a validation study, and, Pearce says, the device not only works, it
“performs as well as commercial proprietary systems for less than 15 percent of
the cost for materials and is 100 percent open source.”
Having freely available hardware and software is only part
of what makes this new nitrate test kit an improvement in the industry.
Making a Better Test Kit
Ellen Campbell, the CEO of NECi, hopes to revolutionize
standard nitrate testing – as well as phosphate testingand other procedures – so that everyone has access to more affordable and more
sensitive equipment. NECi’s nitrate test reagents are close to being
standardized by the Environmental Protection Agency for use under the Clean
Water Act. The US Geological Survey embraced the reagents in their labs.
“But it’s been a long and painful process to reach this
point, because the way scientists think of methods development, and the way the
regulatory community thinks of it, is so different,” Campbell says. Another
challenge, she adds, is establishing a methodology that non-scientists can use.
“We thought, okay, regulators are starting to crack down on
runoff from farms, people want to know that their well water is safe to drink,
and citizen monitors need better tools,” Campbell explains. “We set out to
simplify our enzyme-based methods so that anybody can use them.”
Whether the end user is a farmer, citizen-science group,
water treatment plant or government agency, Pearce and Campbell saw a need to
streamline access to the equipment and data. The device is paired with a free
tablet app provided by NECi and was made using 3-D printing and open source
electronics and software. That not only makes the system less expensive and
more accessible, but also customizable.
Pearce notes in the paper that the device can be adapted for
different chemical measurements as it was derived from their earlier
open-source 3-D printed laboratory work on colorimetersand water
testing platforms. Minor modifications – and different reagents or
complementary tools used to test samples – can create test kits for phosphate,
microbial activity, turbidity, biofuel composition and UV applications.
One of the biggest benefits, Pearce says, is making quality
equipment available to schools. Campbell and NECi have been working with a
school in Virginia to test out the devices in classrooms.
“We need better ways to inspire up-and-coming scientists;
what better way than to have them use real equipment and gather real data in
their communities?” Pearce says. “We are working to make this nitrate test kit
available to everybody.”
