It is important to use sterile sample containers, even for non-biological experiments. Otherwise, bacteria can create a biofilm that can clog the FluidFM cantilever and interfere in your experiments.
Use sterilized consumables (e.g. plates and dishes). In the case of non-sterile consumables, they should be sterilized for example by autoclaving them. As an alternative, you can properly clean them with ethanol.
A good cleaning protocol for FluidFM experiments is described below (from Guillaume-Gentil et al., 2014):
1. Clean dishes with 2-propanol.
2. Rinse them with filtered ddH2O.
3. Dry them with a nitrogen stream.
4. Plasma-treat them for 2 min.
5. The dish is now ready for FluidFM experiments.
Guillaume-Gentil, O., Zambelli, T. & Vorholt, J. (2014). Isolation of single mammalian cells from adherent cultures by fluidic force microscopy. Lab on a Chip, 14 (2), 402-414. doi: 10.1039/c3lc51174j