Usually such problems are prominent in small (or micro) amount of sample flows in a fluidic setup. Use ultrasonic technique to remove any traces of gases. There are certain permeable membranes that allow the fluid to flow but when excited with such U/S vibrations, the gases bubble out through that membrane. Such technique is quite common in Liquid Chromatography methods. So you should have no problem in acquiring any such setup OFF-THE-SHELF to be fitted in your fluidic path.

Hope that suits your requirement.

Best wishes

Thank you for rapid answer.

As your answer, we hope to apply ultrasonic technique in my device.

Which ultrasonic generator is proper micro fluidic device?

I have no ultrasonic device now. however, if I think it is proper to me, I will purchase a goods as soon as possible.

Thanks.

Hello Dongkyu,

As Prasanna mentioned, you could use a porous membrane:

http://www.me.iastate.edu/files/2011/09/bubble_removal_microfl_nanofl.pdf

However, I like the approach of using integrated bubble traps as these can easily be designed into your system:

http://www.nanoctr.cn/xingyujiang/fabiaolunwen/201103/W020120712578587807017.pdf

https://tspace.library.utoronto.ca/bitstream/1807/32258/1/Lochovsky_Conrad_201203_MASc_thesis.pdf

http://www.rle.mit.edu/biomicro/documents/skelley_2008a.pdf

Hope this gives you some ideas.

Hi Jules,

Thank you for your inputs and sharing those documents.

Hello Donkyu!

The setups as per the documents/paper suggested by Jules are indeed useful but I will go a step further and augment the design. I recommend to use Ultrasonic transducer (the transmitter) to be fixed on one side of such fluid-chip. There are simple electronic circuits to drive this exciter at 40KHz frequency that should be sufficient to take out the bubbles in your flow.

Best Luck!

Above all, Thank you for Jules and Prasanna,

To Jules

However, it isn't proper to my condition as it require structural change of my system.

To Prasanna

I'll prepare a circuit and ultrasonic module referring to your opinion.

Thanks,

Thank you Dongkyu for your feedback. I shall be more than happy to help you should you need any further help.

Wishing you a success in your experiment!

What are the materials of construction for you micro channel?  If it is something like PDMS, you can first wet the channel with a lower surface tension solution (e.g., ethanol), then flush it out with plenty of water/buffer prior to use.  Also, it sometimes helps to initiate flow by pulling vacuum on the outlet instead of trying to apply pressure at the inlet.

I think its better solution suggested by Michael. I used this technique in my system and it was very effective instead of using any extra device which my lead to more complicate your design. 

I agree with the two above mentioned solutions. If you don't want to add solvents (like ethanol), you can pre fill the channels with CO2 that lowers the surface tension and should make filling process easier. Depending on your setup, you could also pressurize the complete system, this should keep bubbles at bay. Moreover, if your system is PDMS-based the air should difusse out the chip [http://pubs.rsc.org/en/Content/ArticleLanding/2008/LC/b712672g#!divAbstract].

Good luck!

To Michael, Ahmed

I wonder whether your method is adoptable or not.

As my device uses electric property, prior treatement which you recommend will affect in the channel such as change of conductivity of experimental medium.

Is it OK if I wash channel with experimental medium after prior-treatment?

I suggest that you employ the usage of isopropyl alcohol (IPA) or ethanol , which would help to get rid of the bubbles and then clean clean the channel.

Dear. Abimbola Ashaju.

It seemed that your advice is similar to another one. I worried about that usage of ethanol or IPA change the property of experimental medium. After coating with ethanol, is it completely washed out from the channel?

I suggest the use of hydrophilic channels (e.g. PDMD after plasma treatment). Does not eliminate bubbles but they are removed easily by the flow.

You should also locate the exit of the outlet tube above the microfluidic device to have a higher pressure (above atmosphere) in the channel.

I agree with all

Michael W. Toepke Can the method that you have suggested to remove air bubbles be used with PDMS devices as well? Will ethanol or IPA leach PDMS?

Hello, I would recommend if possible adding a bubble remover accessory to your system ?

https://www.elveflow.com/microfluidic-products/microfluidics-accessories/bubble-remover/?utm_source=researchgate.com&utm_medium=social&utm_campaign=bubbleremoving