Piezoelectric Membrane Actuators for Micropump Applications Using PVDF-TrFE

Abstract

This paper presents the design, fabrication, and performance evaluation of a biocompatible piezoelectric membrane actuator (PMA) using polyvinylidene fluoridetrifluoroethylene (PVDF-TrFE). Electrode structure optimization was verified by a finite element method simulation software. Fabrication was done utilizing only standard microfabrication techniques. 1-μm-thick membrane and 1.5-μm-thick actuator layers were formed by spin coating using PVDF-TrFE. The surface roughness of the fabricated film was measured as 7.9 nm using a tabletop atomic force microscope (AFM) and remnant polarization at 200 V was measured as 5.38 μC/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Deflection measurements were performed with an Al coated tipless AFM probe using a precision nano displacement system, which consists of a ferroelectric tester, a table top AFM, and a computer. A 432 nm displacement was obtained at 9 V under non-resonant conditions from a PMA with 2250 μm diameter. Since all moving structures were fabricated from a polymer material, high displacements could be obtained without fracture. The results demonstrated that the proposed PMA can be a good candidate for membrane type micropumps, especially to be used in biomedical applications, where low driving voltage and biocompatibility are required.