Clinical and Public Health Microbiology

Smartphone App Can Detect Cholera Bacteria in Water Samples Before an Outbreak Starts

Tamara Kinzer-Ursem, Jacqueline Linnes, Steve Werely, and Katherine Clayton of Purdue University have developed a smartphone app that detects Brownian motion in fluid samples.  Brownian motion is the erratic and random movement of microscopic particles in a fluid, and measuring it allows the app to detect the presence of the cholera bacterium, Vibrio cholerae, in water.  The technology was created by a Purdue University spin-off company called PathVis, and the researchers hope to adapt it to detect the HIV and Dengue viruses and the malaria parasite in blood.

“All we needed was a microscope, a camera to capture images, and a computer to crunch the algorithms, and we thought, well, we carry these computers and cameras around in our pockets every day; why not make this portable?” said Kinzer-Ursem.

Placing the technology on a smartphone means that field workers can alert health authorities to the presence and level of pathogens in specific areas in real time, hopefully stopping microbial disease outbreaks before they start.

The researchers recently won the Vodafone Americas Foundation ninth annual Wireless Innovation Project competition.  They will use the $300,000 award to take their prototype to Haiti in November and work with the Emerging Pathogens Institute to test its ability to detect the cholera bacterium in the field.

To use the system, a worker puts a sample of liquid into a small microfluidic chip attached to a smartphone.  If cholera bacterium DNA is present, a chemical reaction on the chip will copy that DNA over and over, producing many DNA strands that increase the viscosity of the solution.  If the bacterium is not present, there is no change in the liquid.

The user then takes a short video of the sample using the phone’s camera equipped with a small microscope.  An app processes and analyzes the video for changes in the Brownian motion of the liquid and flags the sample as contaminated or not contaminated.  The results are produced in less than 30 minutes, compared to the five days it normally takes to send a water sample to a lab and get a result.  A GPS tag in the app records the exact location where the sample was taken so contaminated locations can be compiled into a map by health officials.

For more information, go to the PathVis website ( or the Emerging Pathogens Institute website (