The Microfluidic Aerosol Sampler System (MASS)

LEAH TALBOTT, Andrea Timm, Ryan Darragh, Gregory Merboth, Christopher Stiles, Corrine Morrison, Johns Hopkins University Applied Physics Laboratory

     Abstract Number: 715
     Working Group: Bioaerosols

Abstract
Traditional bioaerosol samplers utilize dry filters or liquid media. However, these techniques are limited: samples require pre-analysis processing (not real-time), have low recovery rates, and use large volumes (mL). Size, weight, and power (SWaP) requirements also limit portability and scalability for field operations. Microfluidic systems that can continuously operate and be integrated with approaches for rapid detection have the potential to produce enriched samples due to low liquid-to-aerosol volume ratios (≤µL). These low cost systems are rapidly emerging as alternatives to conventional bioaerosol sampling systems. In a previous study (A Microfluidic Inertial Aerosol Sampler for Continuous, Efficient Collection and Near Real-Time Detection of Bioaerosols – presented in 2020), we performed redesign and preliminary investigations of the physical collection efficiency (CE) of the of the MicroSampler (Choi et al., ACS Sensors), a microfluidic inertial aerosol sampler, for the purpose of viral aerosol collection. Two-phase stratified flow (sampling air and collection liquid) and inertial deposition provide efficient aerosol collection. As aerosols traverse the curved region of the sampler, centrifugal and drag forces result in the transfer of aerosols from sampling air to collection liquid. In this work, we expanded CE analysis using salt particles (~15 nm to 10 µm diameter) and a Scanning Mobility Particle Sizer (for nm) or Aerodynamic Particle Sizer (for µm), which measured particle concentration upstream and downstream of the sampler. The MicroSampler based design had CE>70% for particles ~15 nm to 500 nm and CE>97% for particles ≥0.5 µm. In addition to experiments, we evaluated commercially available technologies and 3D printing techniques to design a sampler capable of 8-hours of continuous operation. Results indicate that the microfluidic sampler can provide continuous, efficient aerosol sampling for bioaerosols across a variety of flow rates at low cost and with low SWaP.

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