462494 An Integrated Microfluidic System Enabling Real-Time Autonomous Field Surveillance for Vector-Borne Pathogens

Wednesday, November 16, 2016: 4:27 PM
Continental 7 (Hilton San Francisco Union Square)
Robert J. Meagher1, Cameron S. Ball1, Aashish Priye1, Ron Renzi1, Yooli Light1, Jaideep Ray1, Jonathan Helm1, Stephen Mueller1, Mark Claudnic1, Cody Steiner2, Sarah Wheeler2 and Lark L. Coffey2, (1)Sandia National Laboratories, Livermore, CA, (2)University of California-Davis, Davis, CA

Mosquito-borne viruses such as West Nile, dengue, chikungunya, and Zika viruses are important causes of emerging and re-emerging diseases worldwide. We report on a fully integrated, portable, and inexpensive microfluidic chip and chip-handling system that can be deployed in a network to enable real-time autonomous field surveillance for vector-borne pathogens over an arbitrarily sized geographic region. Our system attracts mosquitos to feed on sugar baits and then analyzes mosquito saliva using reverse transcription loop mediated isothermal amplification (RTLAMP) coupled to our recently published QUASR detection method to test for a panel of mosquito-borne viruses, including West Nile virus, western equine encephalitis virus, and St. Louis encephalitis virus. Prototype devices selectively and specifically detect RNA viruses in the laboratory and will be field-tested this summer. The chip handling system, or “smart trap,” enables daily, autonomous sample processing and wireless data transmission to a cloud-based biosurveillance system.

The microfluidic chip’s design minimizes the need for external manipulation and reduces the risk of system contamination. Chips are patterned from acrylic and bonded a thin backing onto the chip. Passive, normally closed microfluidic check valves with adjustable opening pressures are installed using a press fit. An onboard storage reservoir holds rehydration buffer. The chip’s channel geometries allow for dry-storage of all RT-LAMP assay reagents into 8 parallel reaction channels. After desiccation, channel fill and vent holes are sealed off with press fit plug strips that create a gas-tight seal. The chip’s feeding well presents a solid sugar bait to mosquitos, which are attracted to feed by a floral scent. Upon feeding on the sugar bait, mosquitoes deposit saliva which can be tested for the presence of viral RNA. The onboard rehydration buffer dissolves the sugar bait prior to testing by RT-LAMP. The headspace above the sample is then pressurized, pushing it through the second check valve and rehydrating the dried assay reagents. Cylindrical air pockets positioned at the ends of each reaction channel limit the extent of filling.

The smart trap loads one chip daily from a stack of chips that enable autonomous operation for 1 month at a time. A belt drive system moves the chip through different stations in the trap. Linear actuators are used to load chips, dispense onboard fluids, and create a face seal for pneumatic chip filling. A small pump provides the pressure needed to push the sample into the chip. A heater maintains the chip at 65°C for the 30 minute RT-LAMP reaction. Once the chip cools, an inexpensive fluorometer determines whether RT-LAMP reactions are positive or negative. The traps relay data to a master receiver trap, which uploads daily test results to the cloud via text message. A web-based application loads real-time biosurveillance data and overlays test results with vector abundance maps.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

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