This paper presents a piezoelectrically driven microdrop generator based on a diaphragm design. The complete microdrop generator is manufactured by rapid manufacturing techniques, such as laser micromachining. This leads to a short production time which amounts to less than 2 hours per device.
After the fabrication of the microdrop generators they have to be put into operation. This means that they have to be fluidically as well as electrically connected. Therefore, the microdrop generator is bonded onto a carrier board which includes the fluid supply, conducting paths, and soldering pads. Afterwards, the carrier board is mounted on a support plate. Here, a fluid reservoir and heating elements are integrated.
Fluidic investigations are carried out with isopropanol and distilled water for validation purposes. The dependency of the minimum excitation voltage needed for droplet ejection on the pulse width and the relation between the droplet velocity and the excitation voltage are determined. The results show that increasing the pulse width reduces the minimum excitation voltage. The reason is the prolonged energy supply. Ejecting distilled water droplets requires a lower minimum excitation voltage in comparison to isopropanol due to the lower viscosity. Furthermore, droplet velocities are determined for various excitation voltages. A linear relationship between the velocity and the excitation voltage is observed. For excitation voltages greater than 65 V droplet velocities greater than 10 m/s are achieved for isopropanol.