BioImpact

Inspiration

Water scarcity around the globe has generated interest in the potential of water reuse to diversify local water profiles and, in some cases, move towards water independence. However, the removal of an environmental buffer means that real-time monitoring of treatment train integrity are of particular public health and safety concern. Current gold-standard pathogen detection methods are highly reliable and well-established, but often require time for culturing and analysis. These delays can be on the time order of several hours to days and would compromise response time crucial to preventing disease. The lack of a reliable real-time pathogen-detection method also exacerbates public confidence in water reuse systems and limit their implementation. Therefore, our team has decided to develop an integrated capture and detection method for waterborne pathogens in treated water reuse trains.

What it does

When filtering wastewater to render it potable water, it is important to test for the presence of hazardous pathogens and chemicals prior to public dissemination. Current detection methods are time-consuming and require manual wet lab labor. In our project, we aim to identify a viable pathway towards the real-time sensing of waterborne pathogens in wastewater treatment systems. We explored promising pathways to this goal, and developed a methodology that leverages high-throughput microfluidic detection platforms, biochemical properties of pathogens, and 3D-printing for rapid prototyping. Our final proposal is a capture and detection system, in which we capture pathogens using magnetic nanoparticles and detect them through a microfluidic inertial separation device.

How we built it

We began by probing the literature to understand current foodborne and waterborne pathogen detection methods, and to identify key challenges to sensitive real-time detection. We explored multiple methodologies (e.g. impedance sensing, smartphone-based detection, biochemical oxygen demand quantification) before determining that the inertial separation of pathogens from uncontaminated water would be the most effective and time-efficient method. Drawing inspiration from a 2015 Scientific Reports paper, we designed and 3D-printed a preliminary prototype of a microfluidic device that will separate heavier nanoparticle-pathogen complexes from free-floating magnetic nanoparticles (MNPs). To interface this small device with a larger pipeline, we designed a magnetic catchment basin that intakes water from pipelines and from which MNPs will emerge, already having been in contact with pathogens. We plan to use luer lock connectors and syringes to integrate these apparatuses into real-world wastewater treatment.

Challenges we ran into

When we began the project and went deeper into the literature review, we realized we had vastly underestimated the barriers researchers face in creating real-time pathogen detection sensors. Besides the actual task of detection, there was also the problem of sufficiently concentrating pathogens such that they met the minimum limit of detection, and of interpreting the output of sensors, among other challenges. Among numerous competing methodologies that each presented unique advantages, deciding on which would ultimately be the most effective was also a time-consuming process. Finally, once we determined that a microfluidic device was the best method of detection, we realized that these devices are fabricated on the scale of micro or millimeters. It was difficult to imagine how these would possibly be interfaced with large filtration pipelines. Ultimately we devised a step preceding the microfluidic sensor; we would use a magnetic basin to expose pathogens to MNPs in a still container, capturing and concentrating pathogens for greater detection sensitivity.

Accomplishments that we're proud of

We began this hackathon with almost no prior knowledge of sensor fabrication. During the eight weeks we were given, we gained a considerable amount of background knowledge about the scientific principles behind our project, and thought through each step as a team as opposed to glossing over key challenges. We reached out to professors and resources such as the Stanford Product Realization Lab, gaining support and progress in the process of communication. Furthermore, we were able to complete a full-fledged, theoretically robust pipeline to meet our initial project objective, and began the process of prototyping through 3D-printing.

What we learned

Throughout our extensive research process, we learned about ongoing challenges in the field of pathogen detection, the architecture of microfluidic devices, the scientific principles that they rely on, and the principles that were most crucial for our application. In overcoming aforementioned challenges such as micro-macro interfacing, we employed and improved our creativity and engineering skills. The final step of 3D designing and prototyping involved a steep learning curve as well, in terms of becoming proficient in the design software and going through training at the Product Realization Lab.

What's next for BioImpact

Immediate next-steps for BioImpact include applying for grant funding and collaborating with a microfluidic winter lab course to continue prototyping and fabrication of our microfluidic inertial separation device. Once the microfluidic device design is finalized, we have multiple ways of moving forward, including: testing the device with different functionalized magnetic nanoparticles, and conduct pilot-scale experiments to test device integration at the Codiga Research Center.