Inline Bubble Trap with PTFE Membrane
Air bubbles in the fluidic flow can cause significant problems for many applications because the bubbles change the intrinsic physical properties of the microfluidic environment unexpectedly. They could increase the internal pressure abruptly in a fluidic/microfluidic system. It may lead to important shear force variations, resulting in changing the compliance of the system or blocking channels in small size. It is recommended to adding line bubble traps in the fluidic system to avoid and minimize the unintended introduction of bubbles into the fluidic flow stream.
PreciGenome inline bubble trap is able to remove bubbles in the fluidic flow stream with or without vacuum assistance. It effectively avoids blocking by air bubbles downstream in small size channels.
Bubble Trap Specifications
Effective removal of air or gas bubbles (not for dissolved gases)
Internal volume: 25ul, 95ul, and 300ul
Body Material: Peek
Membranes: 10um PTFE
Interface: 1/4″-28 Fittings
Flow Rate: up to 60ml/min for 300ul version (max);
Max Pressure: Up to 30psi
Easy membrane replacing to avoid contamination
No dead volume
Easy to install and place by PreciGenome design
Bubble Trap Principle:
The principle of the bubble trap is based on the interaction of two forces, which are exerted on the air bubbles. These two forces are the hydrodynamic force induced by the fluid flow and the surface tension force induced by the trap walls.
When fluid steam with gas bubbles flows through the trap, the bubbles are expelled through the hydrophobic air-permeable membrane, while it keeps the aqueous liquid inside the flow chamber without any leak.
1) For optimal bubble removal, the bubble trap should be mounted as shown in the Figure: two fluid ports should be positioned at the lowest point which facilitates removed bubbles (gas) move to the top portion of the air path.
2) Connect tubing to the 1/4”-28UNF female threaded ports. Inlet and outlet are interchangeable.
3) To obtain the maximum bubble/gas removal effect, a vacuum source can be connected to the vacuum port.
The bubble trap may operate in a passive or an active mode, which determined by whether an external vacuum is applied or not.
1) Passive mode
In passive mode, the liquid flow goes through the bubble trap without external vacuum applied.
2) Active mode
In active mode, the bubble trap connects the vacuum port to an external vacuum line. In this mode, the bubble trap’s efficiency can be maximized by connecting the unit to the vacuum outlet of a pressure generator or a vacuum source. In microfluidic applications, the bubble trap is typically used in the range of 0.3 – 2.5 ml/min. In other fluidic applications, the flow rate can be increased up to 60ml/min when a vacuum line is applied.
Bubble Trap Q&A
Why choose PEEK traps instead of PVC?
High abrasion resistance
Low moisture absorption
Outstanding chemical resistance
Low coefficient of friction
Excellent wear characteristics
The PVC trap is not autoclavable and is not suitable for organic solvents. While PEEK traps are compatible with most organic solvents used in fluidic applications.
How to select the models?
The main parameter for model selection is the internal volume of the trap:
25 µL, 95 µL, 300 µL.
A smaller internal volume traps less of the liquid solution inside the bubble trap. Therefore, solution usage efficiency is higher. Especially for expensive solutions, the trap with less internal volume is preferred. If the flow rate is really low, a smaller internal volume should work sufficiently.
However, if very higher flow rates(>5ml/min) are required, the larger internal volume should be considered.
Max pressure applied
The maximum differential pressure that the membrane can be exposed to is 30psi. The maximum inlet (positive) pressure is determined by the level of vacuum applied to the dry side of the membrane. For example, a vacuum pressure -12.5psi is applied to the dry side, the maximum inlet pressure should be less than 17.5psi.
How to improve degassing effect
In order to get optimal effect of bubble removal, the pressure difference across the membrane should be large enough. If the pressure difference is not enough, either a vacuum from the vacuum port can be applied or users can create a back pressure in the fluid flow by adding fluid resistance at the outlet port.
De-gassing is effected under positive pressure on liquid flow ports. It is not possible to pull liquid through the unit under vacuum as this would introduce bubbles into the fluid.
However, the vacuum line on the dry side of the membrane can applied up to -14.5psi in active mode. In practice, if -5psi is enough to remove the bubbles from the solution flow, it doesn’t help much to increase the vacuum pressure.
Flow rate range
The typical flow rates used in the bubble trap are between 0 to 2mL/min, but up to 6ml/min can be achieved if few bubbles are present in the liquid. Up to 60ml/min can be achieved for the high-flow trap when a vacuum line on the dry side of the membrane is used.
The bubble removal effect can be optimized by adjusting the flow rate. Generally speaking, lower flow rate, better bubble removal effect.
The bubble trap can only be used for aqueous fluids. If other liquids are used, chemical compatibility with PEEK and PTFE membrane needs to be considered and thoroughly tested.
Maintainance and lifetime
Liftime of the membrane filter highly depends on the fluid used in the unit. For pure water, the lifetime may be several months or years. Buffer solutions reduce the lifetime of the membrane. It is recommended to use de-ionized/distilled water to flush the unit after use to prevent salt crystals forming.
In order to reduce the possibility of contamination from the membrane, it’s highly recommended to change membrane if the bubble trap with the membrane has NOT been used for long time or is used for different solutions.
Cleaning after usage
The lifetime of the membranes strongly depends on the kind of fluid being used. For pure water, the lifetime may be several months or years. If buffer solutions are used, the life will be reduced and it is good practice to flush the unit with DI water after use to prevent salt crystals forming.
70% ethanol can be used, especially in sterile conditions. When cleaning traps with ethanol, take out the membrane and flow water to remove ethanol traces.
NOTE: It’s ok to clean the trap within short time, but with long time contact the organic solvent may damage the PVC bubble trap.While PEEK trap is more chemically resistant
Living cell compatible. The peek and PTFE material used in the trap is completely compatible with live cells.