Why is there no droplet coming out at the end of the probe during filling?
When I fill a FluidFM probe, I would expect the liquid to exit it if I apply pressure. Maybe even form a jet which then reaches the substrate at some point. Why do I not see that?
FluidFM technology is in a sub-micron length scale, where the macroscopic concepts of how water flows are not valid anymore. Very important are surface and interface forces, which are much stronger than gravity for FluidFM probes.
For FluidFM nanopipettes and nanosyringes you will not see any liquid exiting. The surface tension at the opening is too high to overcome with 1000 mbar under typical circumstances. The probes will still be fully operational once filled using our filling assistant in CORA or ARYA.
For FluidFM micropipettes you will see a droplet at the exit building up while applying 1000 mbar, not with lower pressures though. The droplet however will not fall down from the probe irrespective of its size, and definitely not form a water jet.