Intelligent combination of batch fabrication with rapid prototyping techniques for a drop-on-demand microdrop generator

A fluidic experimentation platform, consisting of a piezoelectrically driven microdrop generator which is mounted on a quick-action clamping device, is introduced. Microdrop generators are playing an increasingly important role in many industries. Even though their beginnings were in the printing and coating sector, their strengths are more and more used in other sectors. The wide variety of properties of the fluids like molten polymers, dispersions, or monomers usually require a redesign of the microdrop generator for each application to achieve drops of the size, with the speed, and uniformity that are needed. Therefore, the use of rapid prototyping (RP) techniques for the adaption of microdrop generators to new boundary conditions is indispensable. The presented microdrop generator is based on the diaphragm design. A silicon base plate includes the fluidic components. The number of nozzles is three. Even if one nozzle is clogged two other nozzles are working. The diaphragm is made of borosilicate glass. On top of the diaphragm a piezoelectric transducer is glued. The piezoelectric transducer and the diaphragm form a bimorph actuator. Since only the borosilicate glass and the silicon are in contact with the fluid the assembly is highly chemical resistant to aggressive media. Thus, a very broad range of fluids is ejectable. Besides the laser as main tool a dicing saw is involved in the process flow. Investigations for the optimum machining parameters are presented. In this project four equal microdrop generators respectively 12 nozzles and one further silicon base plate for further quality inspection of the whole batch are manufactured simultaneously. They serve as a good basis for fluidic experiments. Only six process steps are necessary to fabricate one microdrop generator within 25 min. Up to 16 microdrop generators can be batch fabricated in a 4" process chain with rapid prototyping techniques. The realized quick-action clamping device supports a rapid exchange of the microdrop generators and enables future technologies. Here, the electrical and the fluidic connection of the microdrop generator are realized. The microdrop generator is inserted into a groove and is at the same time fluidically and electrically connected via four spring contacts. Special feature is that no gluing or soldering processes are necessary. The device is constructed in a modular way to add further components like a heating cartridge or a fluid reservoir. Overall, the exchange of one microdrop generator can be realized within one minute. The use of the batch fabricated microdrop generator in combination with the presented quick-action clamping device guarantees an efficient execution of fluidic experiments.