DIMATIX Printer Tutorial and Operating Instructions The Operating Principle: The DIMATIX printer is suited to use unusual fluids such as protein solutions or conductive polymers as ink materials. These not usually printable materials are filled into disposable, one time use cartridges. Each cartridge has 16 individually addressable piezo - actuated nozzles through which the fluid is dispensed. The firing voltage of each nozzle can be fine tuned to optimize the printing of the new fluid. A typical voltage cycle consists of three segments: 1) a negative voltage period to fill he cartridge, 2) a positive voltage period to dispense the fluid, and 3) a segment that allows the nozzle to recover to its original shape without drawing in air while doing so. The entire cycle is referred to as waveform. A waveform is optimized when it drives the nozzles such that they dispense perfectly formed drops at a high speed. A waveform that has been optimized for a particular cartridge is called a cartridge setting. Jettable Fluids: Voltage The printer uses an array of 16 piezoelectric nozzles with 21.5 μm openings to produce drops of ink. The fluid used as ink is easiest to print if it has the following properties: 0 Segment 1: Fill Segment 2: Print Segment 3: Recovery Time Actuation of the piezo-driven nozzle. 1. Any particles in the fluid should be less than 0.2 μm in size (100 times smaller than the nozzle openings). To remove large particle aggregates, filter the fluid through a 0.2 μm filter just before loading it into the cartridge. 2. To protect the printing nozzles from drying out it is best to use inks that evaporate only slowly. If a fluid evaporates too fast, glycol may be added to it. Glycol lowers the evaporation rate of aqueous fluids. Please note, that for safety reasons, solvents with a flash point below 120 ºC are prohibited in the printer. 3. The viscosity of the fluid should be between 10-12 cps (1x10-2 Pa*s). If the viscosity of a fluid is too high, it is possible to lower it by heating the print head (up to 70ºC). 4. The surface tension of the fluid should be between 28 and 33 dynes/cm2 (2.8-3.3 N/m2). Add a surfactant to aqueous fluids to increase their surface tension. 5. Degas aqueous fluids to prevent the formation of bubbles during printing.
1. Convert a Tanner (LEDIT) File to a Drop Spacing File: Open the file in L-Edit. Export it as a gerber file (File, Export mask data, [Gerber] ). Specify the All user gerber file folder as the export destination and click OK. To run the drop manager, the printer needs to be turned on: Verify that the printer stage is empty, then flip the power switch on. Open the Dimatix Drop Manager by clicking on Choose No in the appearing window. In the drop manager select the Print Set-up tab. In the drop manager select Tools, then Pattern editor (bitmap images). The Image to Pattern Converter window appears. Under the substrate tab, edit the drop spacing (20 microns is a good start for a new fluid). Under File, select Open Gerber and choose the pattern file. Then click on Open. The pattern will appear in the window.
Determining the Optimum Drop Spacing: The behavior of the printed fluid drops on the substrate determines the optimum drop spacing. For example, the optimum drop spacing for an aqueous fluid on a hydrophilic substrate is larger than that on a hydrophobic substrate. As a general guideline, set the drop spacing to half the size of the deposited drops. The printer realizes a particular drop spacing by rotating the printing cartridge. The maximum drop spacing at a 90 degree cartridge angle is 250 microns. To optimize the drop spacing for a fluid/substrate system, print a pattern with an estimated drop spacing first. Evaluate the print and adjust the drop spacing for subsequent prints. Keep in mind that each drop has a volume of 10pL. Print direction The drop spacing is achieved by rotating the cartridge. Aqueous solution on a hydrophobic substrate. Aqueous solution on a hydrophilic substrate. Under the Placement/Tiling tab edit the number of X and Y counts (i.e. rows and columns) as well as the pitch. Under the Reference Point tab, make sure the box next to Use Reference Point is checked. Specify the reference point by clicking on Set Ref Point and clicking on the point in the patter. If no reference point is specified, it stays at the default location at 0,0. The Reference Point: The reference point determines where a the new pattern is aligned with an existing pattern on the substrate. Pattern on substrate Pattern to be printed Overlay Click on Tiled preview to preview the pattern. Save the file in the All users drop spacing files folder and close the Image to Pattern Converter window.
Now, load the pattern: In the drop manager (under the Print Setup tab), click on select in the Print Pattern field. Choose the converted drop spacing file (it will have a gerber extension) and click Open. If the cartiridge angle needs to be changed, the software will prompt you to do so now. Adjust the cartridge angle: Open the printer lid. Open the small black latch on the cartridge carriage and turn the cartridge to the desired angle. Turn the latch back and close the lid. Click Ok in the message window. 2. Load the Cartridge and Optimize the Cartridge Settings: Fill a syringe with the fluid you wish to print. Place the filter and tip on the syringe. Push the ink into the cartridge. Snap the two halves of the cartridge together. In the drop manager, select the Replace Cartridge tab. Let the cartridge carriage move into place. Open the lid. Insert the cartridge into the carriage with the electrical connection pads facing the back. Snap the black lever down so that it locks the cartridge in place. Close the lid. Load the Cartridge Setting: Under the Print Set-up tab click on select in the Cartridge Settings field and choose the a previously adjusted cartridge setting, or - if this is the first time you work with this fluid - choose a waveform that describes your fluid best. Click Open.
Click on Drop watcher in the lower left of the drop manager window. The Drop Watcher window and the Cartridge Settings windows will appear. For every cartridge angle, the nozzle spacing changes. The movement of the stage needs to be adjusted so that it is possible to move to a particular nozzle for the purpose of examining the drops fired by this nozzle. Therefore, calibrate the nozzle view first: In the Drop watcher window go to Tools and select Calibrate Nozzle View. Find the right most nozzle (=nozzle #1) and click-drag it to the cross hair. Use the focus buttons to refine the nozzle s focus. Click Next in the lower left of the drop watcher window. Bring the left most nozzle (=nozzle #16) under the cross hair. Click Next in the lower left of the drop watcher window. Run a cleaning cycle to fill the nozzles with fluid: Press Run now in the Cleaning Cycle window. Repeat this process whenever the nozzles seem to be clogged. Apply a voltage to nozzle # 8 by checking the box next to number 8 in the Firing Nozzle window. Click on Strobe Delay and adjust the slider so that the drop is visible as far down as possible, but not below the 1000 micron mark. In the Cartridge Settings window adjust the voltage for nozzle number 8 until an optimum drop is forming. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 The optimum drop is a round drop without ligament at the 1000 micron mark. Now, check the box for an adjacent nozzle and repeat the process such that the two drops have the same velocity. Do this for as many adjacent nozzles as possible. 100 micron 500 micron 1000 micron slow drops optimum drops drop with ligament stray drop
Adjusting the waveform is optional. Skip ahead to below the following box if you were able to achieve good drop formation with the steps described on the last page. If not, adjust the waveform as described in the box. If no drop forms (and the nozzles are not clogged, i.e. the cartridge is new), edit the waveform: press Edit in the Select Waveform window. The waveform window will open. Adjust the length and scale of each segment in the waveform for one nozzle (#8) first. Watch the drop on the screen change velocity and shape. All adjustments are real time. Start with the duration scaler. It adjusts the pulse width (length in micro sec). At optimum pulse width the speed of sound in the fluid is matched to the acoustic characteristics of the pumping chamber. Adjust the pulse width by sliding the duration scaler so that a drop is ejected with maximum velocity. The higher the fluid viscosity, the longer the pulse width should be. Now adjust the individual segments to optimize the drop formation. Segment 1: Fill Segment 3: Recovery During Printing Steepness of the slope provides the energy for fluid ejection Segment 2: Firing Pulse Dampening segment: prevents intake of air; also brings the PZT back to null position. While at Rest When the first nozzle is adjusted, save the waveform under File and Save waveform in the Cartridge Settings window. Close the Waveform Editor window and load the edited waveform for all nozzles by clicking Select and choosing the saved waveform in the Cartridge setting window. Now adjust the voltage for several nozzles so that they fire drops at the same speed. When as many adjacent nozzles as possible fire drops with the same velocity, specify these nozzles in the Cartridge Settings window under the Cartridge tab.
In the Cartridge settings window, choose the Cartridge tab, then select Enable advanced features under the Tools menu. Type in the number of adjacent nozzles that fire at the same speed, as well as the number of the first of these nozzles. Save the waveform under the Waveform tab. Close the Cartridge Settings window and the Drop watcher window. Re-load the waveform by selecting it in the Cartridge Settings field of the drop manager window. 3. Load and Align the Substrate: Load the Substrate onto the stage. Type the substrate thickness and the temperature into the corresponding fields. Align the Substrate and Specify the Reference Point: Click on Fiducial camera. The Fiducial Camera window will appear.
To align the substrate to the cartridge, specify two alignment marks. If you don t have alignment marks, choose two points in the pattern. The stage then rotates to align the substrate and cartridge. Cartridge print direction Start by setting the light intensity and by focussing on the substrate. Click on Calibrate theta in the Tools menu. Follow the instructions in the window: Click on Set Start Position. Click on the first alignment point on the sample. Now move to the second alignment point, click on it, and in the window click Ok. The stage will rotate to make the line specified by the two alignment points parallel to the cartridge print direction. Set the reference point. Make sure there is a check mark next to Use Reference Point. Under the Tools menu select Set Reference Point and click on the appropriate position on the substrate. Close the Fiducial camera window. Now click on Print in the Drop manager window. Click Ok in the popup window. Turn the printer off.