A lab on a chip helps provide the answer—which is a matter of life and death when the question is whether drinking water contains arsenic.
More than 800 million people worldwide lack access to clean water. In developing countries, especially in South Asia, groundwater resources are often contaminated by naturally occurring arsenic. In Bangladesh, nearly one-quarter of the tube wells contain toxic levels of the colorless, odorless, and tasteless heavy metal.
|How it works: The sensor, layer by layer and step by step. Click on the image for a larger version. Ilustration by Steve Stankiewicz
Existing technologies used to test water sources for arsenic are lacking, says bioengineering student Jessica VanderGiessen ’14. Colorimetric tests—similar to a pH test used to measure the level of chlorine in pool water—are cheap, easy to use, and deliver results in the field, but the devices have serious drawbacks: They use toxic chemicals as reagents, they cannot detect low levels of arsenic, and they deliver imprecise results. Laboratory tests, meanwhile, are accurate but more expensive and require transporting water samples from remote areas to labs in major cities.
With assistance provided by the School of Engineering’s Frugal Innovation Lab, VanderGiessen and bioengineering students Alexandra Sibole ’14 and Ben Demaree ’14 have developed what they believe is a better way to test for arsenic. VanderGiessen says the team’s solution delivers the precision of sophisticated laboratory testing, in the field, via a handheld device that uses cheap, disposable materials and is operated by a single user.
The prototype combines three components—a sensor the size of a human pinkie, an electrochemical analyzer the size of a human hand, and a mobile phone—all powered by a laptop computer.
The sensor uses a printable-ink silver electrode embedded on a plastic-based substrate. A one-button system runs the arsenic test on a water sample. The electrochemical analyzer displays a peak; the height of the peak corresponds to the concentration of arsenic in the sample. Test results are uploaded via mobile phone to a central database for geocoding on a map.
Frugal, not simple
The arsenic testing device is one of the most promising student projects to have been nurtured by the Frugal Innovation Lab. Since the lab’s April 2012 launch, more than 350 students have made use of its resources. At any one time, the lab is involved in 20 to 25 projects, says its director, Radha Basu. Basu is also the Regis and Dianne McKenna Professor of Science, Technology, and Society and holder of the Dean’s Executive Professorship. She describes the lab’s mission as “designing appropriate, accessible, adaptable, and affordable technologies, products, and solutions for the needs of emerging-market consumers.”
Design and material choices demand thrift and creativity, says VanderGiessen. Using silver rather than gold for the electrode cut costs, and switching from paper to plastic for the substrate improved durability. “We really wanted to come up with a disposable sensor that could conduct testing at the point of care, so people could have immediate feedback as to the quality of their water.”
Basu says some people hold a mistaken belief that frugal innovation is easy or means “cheap.” Not so. “It might sound like, ‘Oh, frugal innovation, that’s simple,’ but it actually makes the engineering and the requirements more stringent. Designing for resources-constrained environments needs develop unique skills for our students.”
It’s not just users of the technology who recognize the value in those skills. So do corporations. “We say to our students: ‘You’re sought after because you have this training in frugal innovation and innovation for emerging markets.’ As the markets shift globally, businesses will increasingly need students to understand how to design for the developing-world consumer.”
VanderGiessen conducted field testing of the arsenic detector in rural eastern India, in partnership with St. Xavier’s College, in July 2013. VanderGiessen, who was in Kolkata that summer working for a nonprofit as part of the Leavey School of Business Global Fellows Program, performed the field research on weekends. Funding for the fieldwork came in part from the Frugal Innovation Lab.
Rely on it
In the coming months, the student team will be busy preparing the device for commercialization and improving the prototype. The student team identified required tweaks based on the device’s performance in the India field trials. The height of the peak on the electrochemical analyzer must be calibrated to a precise arsenic level so that users need not interpret the height of the peak themselves. The connection between the sensor and electrochemical analyzer must be improved to make sure that the components work together seamlessly. Last, the students will ensure that the device can detect arsenic at low concentrations, such as the World Health Organization standard, and that it is detecting only arsenic. Later, the students plan to investigate whether the arsenic detector can be equipped to detect lead, mercury, and other toxic heavy metals as well. Basu is helping VanderGiessen register the intellectual property for the device.
If these obstacles can be overcome, Basu is confident that the technology will succeed in the market. “If it can be built out at scale, it can have a tremendous set of applications. It can be used all over the world by consumers, travelers, individuals in disaster areas, social enterprises, nonprofits, and government workers who are going to map the arsenic.”
For her part, VanderGiessen clearly feels a responsibility to engineer a device users can rely on. Their lives may depend upon it. “It’s one thing to test a water sample I’ve spiked myself with arsenic in the lab,” she says. “It’s another thing to test someone’s only access to water and have them look you in the eye and ask whether they should continue drinking it.”
Arsenic is tasteless and odorless, so someone might continue drinking it without knowing. And the adverse health impacts stemming from arsenic poisoning may not appear until long after the consumption of contaminated water. Exposure to arsenic causes a host of ailments, including cancer of the bladder, lungs, skin, and kidneys.
The practical application of frugal innovation methods embodies, for VanderGiessen, what engineering can and should be. Here’s a device that meets a basic human need. And it could, she says, “genuinely be used to help the people around me.”