| Popis: |
This paper reports on a simple, disposable non-contact dispenser for the nano- and microliter range. In contrast to other known dispensers manufactured by silicon micromachining1-4 the new device simply consists of an elastic polymer tube with a circular cross section. Actuation is done by a piezostack driven piston, squeezing the tube at a defined position near the open end by a significant fraction of the cross section. In contrast to drop-on-demand devices based on an acoustic actuation principle,5 the squeezing of the tube leads to a significant mechanical displacement of the liquid. Our experiments tested a large number of media in the viscosity range from 1 to 27 mPas. Some of our experiments tested up to approximately 2,000 mPas. Frequency characteristics showed an independent dosage volume for water up to a frequency of 15 Hz for tubes with an inner diameter of approximately 200 um. Standard deviation within 1,000 shots resulted in an excellent CV (standard deviation/dosage volume) of less than 2% of the dosage volume. Using tubes with an inner diameter of approximately 1,000 um and a print frequency of 340 Hz, a flow rate of less than or equal to 143 μL/s could be reached. Beyond the possibility to dispense pure liquids, emulsion paints with particles that have a diameter of approximately 40 μm have also been printed successfully. |
