Ultrasound burning holes

[eliebs74]

I have recently run into a problem where I have 2.6 MHz ultrasound passing from a transducer into fluid, through a plastic barrier and back into fluid. For some reason I keep burning holes in the plastic barrier. The plastics that I have tried are PET, Teflon, and PE. Any suggestions ?

 

[hacksaw]

you may be dealing cavitation. hardened materials will improve the situation.

 

[eliebs74]

hacksaw,
thank you for your response. A hardened material is better however, I need a material with an acoustical impedance equal to that of water. I am not sure if cavitation is the problem or the ultrasound is being absorbed by the material. i probably should have stated that the ultrasounic signal is focused about 1 mm above the surface of the cup. Thank you.

 

[hacksaw]

a properly designed mesh does not necssarily require that the material of the mesh match that of water.

are you exciting standing waves in the fluid?

 

[eliebs74]

Yes I am exciting standard waves in the fluid.

 

[hacksaw]

try repositioning your screen

 

[eliebs74]

I can not reposition the screen for reasons I can not divulge. If possible, I would not make any changes to my test setup. The ideal solution for me is the correct material that will not burn as the ultrasound passes through it.

 

[mkeough]

I'm not exactly sure what you're trying to do with the plastic material, but you say you used (solid?)"teflon", in sheet or extruded form. I'm assuming that the plastic is some kind of fluid barrier??

If so, have you tried some teflon membrane materials such as Gore-Tex that prevent some fluid flow, but may allow for better ultrasound energy to pass?