Experimental Characterization and Simulation of a Piezo-Actuated Micro Dispensing Valve
The dispensing behavior of a piezo-actuated micro-valve that closes the gap between the nanoliter range (e.g., inkjet technology) and the microliter range (e.g., standard displacement technology) has been investigated by experimental and numerical means. Water and different Newtonian model fluids with defined fluid properties were utilized for experimental characterization. The dispensed amount per single dispensing event could be freely adjusted from a few nanoliters to several hundred microliters showing the large working range and flexibility of the micro-valve, while maintaining a high accuracy with a low relative standard deviation. A correlation between fluid properties, dispensing parameters, and the resulting steady-state mass flow was established, showing good consistency of the experimental data. Furthermore, a three-dimensional numerical model for the quantitative simulation of the micro-valve's dispensing behavior regarding fluid mass flow was developed and validated, showing a high degree of correspondence between the experiments and simulations. Investigations of the transient behavior after the opening of the micro-valve revealed a nonlinear relationship between the valve opening time and dispensed mass for short opening times. This behavior was dependent on the working pressure but independent of the type of fluid.