NanoDispense for the FTA4000
The NanoDispense method involves the following steps:
- Prepare a spherical cap of liquid on the bottom of the dispense tip.
- Gauge the distance to the surface using image processing.
- Start Movie capture.
- Move the tip down to the surface so the liquid on the tip bottom wets the surface and forms the beginning of a sessile drop.
- Trigger the Movie.
- Maintain the proper pressure in the tip liquid and raise the tip and, in so doing, break the meniscus between the sessile drop and the liquid still on the tip.
The profound benefit of the NanoDispense method is that these are all done automatically, at the press of a single Dispense button.
The user does have some options, should they be useful:
- The preparation of the spherical cap of liquid on the tip can be skipped. This is useful if the user wants to manually prepare this or there is already an appropriate amount on the tip.
- The dwell position of the tip at the bottom of the stroke can be adjusted to provide for a little more or less liquid in the drop.
- The method can be operated in a Test mode that does not actually dispense any liquid but does show the motion of the tip.
The NanoDispense pump can pump reasonable liquids directly through it. Some liquids, though, you may prefer to keep out of the pump and its plumbing. An example is ink jet ink. An accessory allows you to inject ink into the needle through a side port. The water from the pump then controls the dispense. An airgap separates the pump water and the needle ink.