I'm trying to scan the surface of E. faecalis biofilms on glass slides however when using AFM in liquid mode, I get nothing. My theory is that E. faecalis produce weak biofilms that lift off as soon as the cantilever comes in contact with it. Any tips on immobilization? I didn't think I would need to immobilize the cells as it's a biofilm but nothing is working. I've tried PEI but I'm not getting good images.