How can I avoid clogging in my probe?
A clogged probe often means the end of the experiment, thus it needs to be avoided as good as possible. Keep in mind that FluidFM probes have dimensions in the single micrometer range or even just a few hundred nanometer. Thus particles, surface forces, micro-bubbles and surface evaporation are all critical factors during operation.
By following a few simple rules clogging of probes becomes very unlikely, though:
Add glycerol or other non-evaporating liquids to your probe filling if possible. Drying out - a major cause of probe failure - will be eliminated.
Use only filtered liquids. Filter with 0.2 um pores sizes.
Degas the liquids.
Avoid unstable suspensions or aggregates.
Fill the probe completely and make sure no air bubbles remain in the channel.
Always apply a slight over-pressure to the probe (20 mbar) until it is fully immersed in liquid, to avoid any bubbles entering from the front.
Avoid prolonged exposure to air once a probe is filled, especially for micropipettes. Nano-pipettes can often be used for hours in air, while micropipettes will dry out after minutes.
Clean and rinse the probe before storage. Avoiding salt crystallization and bacterial contamination will allow to store the probe fo up to one week.