CHARACTERIZATION OF VALVELESS PIEZOELECTRICALLY-ACTUATED MICROPUMPS WITH NOVEL DIFFUSER ELEMENTS

Micropumps can play a significant role in thermal management applications, as a component of microfluidic cooling systems. For next-generation high density Photonics Integrated Circuits (PICs), in particular, heat flux levels are sufficiently high to require a microfluidic circuit for cooling. Valveless piezoelectrically-actuated micropumps are a particularly promising technology to be deployed for this application. These pumps exploit the asymmetric flow behaviour of microdiffusers to achieve net flow. They feature no rotating or contacting parts, which make them intrinsically reliable in comparison to micropumps with active valves. In this paper, two novel microdiffuser elements are reported and characterized. Both elements are based on a standard planar diffuser/nozzle element, with additional protrusions to reduce the overall backflow. The micropumps were fabricated using a 3D printer. Each single diffuser had a length of 1800 μm and a depth of 400 μm. An experimental characterization was conducted in which the flow rate and differential pressure were measured as a function of operating frequency. In comparison with the standard diffuser, both elements showed an increase in differential pressure in the range of 40 – 280%, but only one element exhibited an improved flow rate, of about 85%. The primary outcome of this work is a set of microdiffuser elements for a piezoelectrically-actuated micropump which yield enhanced performance compared to standard diffuser/nozzle elements. A secondary outcome is the successful demonstration of 3D printing as a fabrication technique for a microfluidic component.