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Micro-atmospheric Microwell Plate Technology

Principal Investigator: Michael Flynn

Microwell-plate technologies are commonly used for bioassays, combinatorial chemistry, and cell culture experiments and are ideal formats for use as small satellite payloads. However, valuable research in space science cannot be effectively accomplished without significant improvements in our ability to deliver, remove, and measure gases in these formats. Complications arising from spacecraft atmospheric variations and the buildup and depletion of gases in solutions at the micro-scale can mask subtle interactions that are critical to achieving microgravity science objectives. This work will evaluate the feasibility of developing a sealed microwell-plate with a micro-atmospheric control system. Such technology would enable a wide range foundational research in Space Synthetic Biology, Fundamental Space Biology, and Astrobiology, ultimately generating knowledge required to engineer a potentially broad range of space biotechnology applications.

In microgravity, where buoyancy driven mixing is minimal, the buildup of carbon dioxide in solutions containing bacteria can adversely impact growth rates and mask more subtle effects. Likewise, the delivery of oxygen and removal of metabolic by-products at the bottom of a microwell in microgravity is difficult to achieve and even more difficult to measure. Gas that builds up and is not removed will supersaturate the growth medium and form bubbles causing interference with detection and analysis instrumentation. Also, the control of humidity levels in a microwell is important. What is needed is a standard microwell-plate that is sealed with a transparent cover slip and has the capability to control, mix, and measure gas concentrations inside the microwells. This work will demonstrate the feasibility of two key aspects of the system. These include the demonstration of the capability to measure gases at a nano scale at the bottom of a microwell and a study of the benefits of growing a microbial culture in a sealed microwell with a controlled micro-atmosphere.

Work to date includes a preliminary design study of a micro-atmospheric system including an engineering assessment of a microwell-plate microfluidic system, survey of potential sensor systems, and potential adsorbents. The system incorporates a new class of nanosensors to measure gas concentrations above a growth medium, gas phase adsorbents as gas reservoirs and partial pressure control actuators, and micro pumps and valves to circulate gases and insure good mixing. The technology will provide a method to assess and control atmospheric variation and nano-scale mixing in biological or non biological payloads.