Researchers at the University of Waterloo have invented a fast, affordable way for developing communities to test their drinking water for potentially deadly E. coli.
Unlike current tests that cost about $70 and can take up to three days to get back from the lab, the Waterloo invention uses paper strips similar to those in litmus tests to produce results in less than three hours at a cost of 50 cents.
"This has the potential to allow routine, affordable water testing to help billions of people in the developing world avoid getting sick," said Sushanta Mitra, executive director of the Waterloo Institute for Nanotechnology. "It is a breakthrough."
Now being refined by Glacierclean Technologies Inc., a startup company co-founded by Mitra, the test could also improve water safety in remote or rural areas of the developed world and greatly reduce testing costs for municipal treatment systems.
Researchers targeted E. coli - the culprit in a deadly outbreak in Walkerton, Ontario in 2000 - because it is an indicator organism of water contamination.
The bottom of the paper strip developed by Mitra and his colleagues is laced with sugar, which begins to dissolve when placed in water. E. coli bacteria are attracted by the resulting sugar trail and get trapped in the porous paper when they come in contact with it.
As water enters the paper, it carries the trapped bacteria into an area of the strip containing a mixture of chemicals. The E. coli react with those chemicals and turn the strip pinkish red to signify a positive test.
With high levels of contamination, a result is produced in just 30 minutes. Low levels of contamination take up to 180 minutes. Work is underway to reduce test times.
Glacierclean, which already sells mobile water kits to detect E. coli for about $5 a test, hopes to have its DipTest strips on the market within nine months.
"Simple ideas create paradigm shifts in technology and this is a simple, frugal innovation," said Mitra, also a mechanical and mechatronics engineering professor at Waterloo.
Mitra's research—done in collaboration with Naga Siva Kumar Gunda, a post-doctoral fellow and co-founder of Glacierclean, and former master's student Saumyadeb Dasgupta—appears in the journal PLOS ONE.

In what could be the first time, a measurement of the strength of general relativistic effects has been achieved from stars orbiting close to a supermassive black hole. Tested against a strong gravitational field which holds even under extreme conditions, this recent research might support the effects of predictions made by Einstein’s general relativity.
Shrouded in a cloud of gas and dust in the center of our galaxy is the black hole is known as Sagittarius A* (Sgr A*), the closest supermassive black hole which had been deduced to have a mass four million times more massive than our Sun. This giant monster is surrounded by a group of stars orbiting at high speed around the black hole’s strong gravitational field which makes it an ideal environment to test the general theory of relativity.
A group of astronomers in Germany and the Czech Republic had been tracking the movements of three stars orbiting near Sgr A*. Using data from the ESO’s Very Large Telescope (VLT) in Chile and other Telescope for the past 20 years, astronomers applied a new analytical technique, which deviates the predictions of classical physics. Instead, it hints support of the subtle effects predicted by Einstein’s general relativity.

The closest known star to Sgr A*, known as S2, showed hints of a small change in motion, indicating relativity effects. It’s a slight change, about one-sixth of a degree in the orientation from the orbit, and a few percent of its elliptical orbit’s shape.
“To determine relativistic effects for S2,” Andreas Eckart team leader at the University of Cologne realized during their analysis that “one definitely needs to know the full orbit to very high precision.”