Goals of the project
Arsenic contamination of groundwater is a global health problem affecting millions of people. Long-term exposure to arsenic has been linked to a variety of cancerous and non-cancerous health effects. Current diagnostic technologies for arsenic quantification are limited to either inaccurate colorimetric methods or expensive, off-site lab assays, which are unsuitable for resource-limited settings. To address this need for an affordable and rapid means of sensitive arsenic detection, our design project focuses on the design and fabrication of the first point-of-use microfluidic device capable of electrochemical detection and quantification of arsenic levels in groundwater sources. We fabricate our device rapidly and inexpensively using laser cutter technology to machine thin layers of acrylic plastic, which are then bonded using double-sided tape. To fulfill the needs of resource limited communities, our broad benchmark goals include a sensor sensitivity below 10ppb, containing the acid within the sensor to prevent interaction with the user, and ensuring affordability by keeping costs below $1 per sensor.
Nature of the Collaboration
Our system consists of three primary components: the disposable microfluidic sensor, the miniaturized potentiostat, and the mobile application. After clearly defining project goals that each component needs to fulfill, teams were broken up by concentration to work on each of these components. The bioengineering team focused on the sensor, the electrical engineering team on the potentiostat, and the computer engineer on the mobile application. Teams met up weekly to go over progress and discuss any potential obstacles to work through as a group.
For the microfluidic sensor: screen printing, materials printing, design and manufacturing methods, and technical drawings were all skills used to produce and evaluate prototypes.
For the miniaturized potentiostat: coding, soldering, bread boarding, and circuit mapping were all used to design and alter circuit board.
For the mobile application: coding and interface design were used.
The laser cutter has been used consistently throughout the arsenic detection project. Initially, the laser cutter was used to cut defined electrode patterns onto paper substrate to be used as stencils for applying the conductive ink. In spring of 2013, a major milestone was achieved by developing a fully enclosed disposable device. This device included several plastic layers with defined holes and chambers, all of which were laser cut in the Maker Lab. The disposable electrodes were also laser cut in order to produce uniform shapes and orientations. The laser cutter has been essential to our production of the enclosed devices and has greatly increased the consistency of our technology device to device.
The original project idea was focused primarily on developing the sensor. After the first prototype was created in 2013, electrical and computer engineering teams were brought in to work on integrating the miniaturized potentiostat and mobile application.
The first sensor prototype was finalized in spring of 2013. That following summer we took that proof of concept technology over to Kolkata, India, to conduct our first round of field testing on 33 water sources. Our second sensor prototype was finalized in spring 2014, which was much more sophisticated and successfully integrated with a portable potentiostat. The third prototype we are working on right now is working to integrate the sensor with both the potentiostat and mobile application.
The first challenge encountered was determining the proper substrate for the biosensor. Initially, we were hoping to employ a paper substrate to increase affordability and reduce waste. However, paper proved to be highly inconsistent, so we decided to employ a thin plastic substrate that produced much higher quality and consistent results. The process taught us to seek creative solutions and alternative methods when faced with a challenge that is difficult to overcome in order to avoid design bottlenecks.
The first major project outcome involved testing our first two sensor prototypes and proving a positive correlation between arsenic concentration and electrochemical peak, which is the generated outcome of our device. This outcome proved our technology was successful. Another major project yield occurred in spring of 2013 when we proved successful integration between the sensor and a portable potentiostat.
Innovations, impact and successes
The sensor has definitely seen the most innovation, from initially being a single sheet of plastic with painted electrodes to now a fully enclosed device complete with sensing chamber and spotted paper to acidify the water sample.