How to Eliminate Bubbles from a BioFlux Plate

Mitigating the effect of gas bubble on flow and imaging

 

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  • The inlet ‘fingers’ at the inlet of high-shear plates (0-200 dyn) are prone to gas bubbles post prime; bubbles can also remain in low shear plates at various points along the channel (bc 0-20 plates)
  • Gas bubbles significantly decrease flow rates, especially at low dyn values (i.e. 5dyn)
  • This guide provides recommendations for priming to remove gas bubbles

The ‘fingers’ at the inlet of high-shear plates (0-200 dyn) are prone to gas bubbles post priming

Images of bubbles at fingers post prime (bright field):

Eliminating bubbles

  • Bubble formation may be minimized by priming at high shear rate. A full inlet well (1mL) of PBS can be primed at
    • –  150 dyn for 6 minutes or
    • –  200 dyn for 4 minutes
  • In this example, Ch3 was primed with PBS and Ch4 was primed with water at 150 dyn for 6 minutes. Some air bubbles were observed in the channel of Ch4 and at “fingers” (not pictured)
  • Note that water (ch 4) has a few bubbles remaining post prime

Eliminating bubbles – if needed

  • If bubbles are still observed post priming – eliminate them by pressurizing both inlet and outlet as shown below:

  • Disconnect the tubing from a non-corresponding column (i.e. valve). In this example, column 2 was disconnected.

  • Insert the tubing from another non-corresponding column (i.e. any column; in this case, column 4 was used)

  • Column 2 is now pressurized by column 4 (see next slide)

  • You should only have to perform this on rare occasions if priming recommendations are followed

Eliminating bubbles

Under manual mode, pressurize the column by simultaneously activating both columns at 200 dyn for 15 minutes or until all bubbles have eliminated.

Flow Consistency Conclusions

  • Standard deviation should be within 10% for flow measurements, excepting rare channel failures

  • To achieve consistency, priming needs to be complete; please follow the following rules:

    • Pre-warm PBS to 40C before priming (avoid priming with pure H2O)

    • When loading priming media, gently triturate to eliminate bubbles in the inlet and/or outlet

      wells before priming.

    • All air pockets/bubbles in the bottom of the well must be removed before priming

    • Prime at the highest available shear (10 psi pressure applied), 20dyn for low shear plates;

      150 to 200 dyn for high shear plate

    • Until high confidence is achieved:

      • Inspect the plates for bubbles post prime, esp. in the inlet and outlet regions

      • If necessary, eliminate any bubbles as described

    • Bubble issues may be more prevalent for certain channels based on position on the plate

      and surface roughness near the inlet/outlet