The membrane can only be tested in a whole form and not in powder form. This rules out the agar disc-diffusion method and also the broth/CFU count method. Does anyone have any other idea? I actually tried the disc diffusion method using the polymer membrane cut into small discs. I got some results (minimal clear zones) but I seriously doubt its authenticity because the materials being tested for antimicrobial activity are immobilized inside the polymer membrane. Therefore, how did the antimicrobial activity get beyond the membrane on the agar?