Resonant microfluidic circuits for assay automation and detection in point-of-care diagnostics

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PI: Lutz, BarryInstitution: University Of WashingtonIntellectual Merit: The field of microfluidics aims to create portable "laboratories" to carry out analytical tests. Devices are typically simple polymer cards that require supporting equipment to control fluids (e.g., pumps, valves, controllers) and detect test results (e.g., imaging). A key challenge for point-of-use medical diagnostics, environmental monitoring, bio-threat detection, etc. is reducing the expense and physical burden of the instrumentation. Nearly everyone has a cell phone that could serve as a test instrument- they are ubiquitous, battery-powered, easy-to-use-and they are capable of generating, detecting, and communicating information-rich audio signals. We envision a disposable test card connected to a phone earbud, where audio tones (1) control fluidic steps by "talking" to the card, and (2) quantify test results by "listening" to the output from the card. The principle is based on a classic analogy between electrical and fluidic circuits. In electrical circuits, useful functions are created via simple combinations of resistors, inductors, capacitors, and diodes (e.g., a radio tuner). By using oscillating flows in microscale channels ("AC microfluidics"), we can resurrect functions that we know from electrical circuits. This proposal aims to develop AC microfluidic circuits that perform analytical functions for point-of-use testing. Fluidic versions of classic electrical circuits will be created (e.g., band-pass filters), and measurements of the fluidic circuit frequency response will be compared to electrical circuit models. A "microphone" will be incorporated into cards to measure circuit output, and audio-based sensing circuits will be developed via model-based design and experimental validation. Signal transduction chemistries will be developed that produce physical changes in a circuit component, and the system will be used to detect a malarial biomarker. Broader Impacts: The grant will support student projects in the cross-disciplinary field of global health diagnostics, which offers rich educational experiences that require integration of engineering with broader issues of health, culture, ethics, regulatory procedures, and commercialization in low-resource settings. The global health focus also introduces unique constraints on engineering (simplicity, cost, ease-of-use) that often require creative and simple solutions. Technology for global health needs will be highlighted in public outreach including hands-on exhibition at our annual Engineering Open House. Undergraduate students will participate in design projects to develop card-to-phone interfaces and cell phone "apps" for on-phone data analysis, and the PI will host a group of students in the laboratory as part of the UW STEM Bridge program that aims to encourage underrepresented students to pursue careers in science, technology, engineering, and mathematics disciplines.