Printed Piezoelectric Thin Films Via Electrohydrodynamic Deposition

Piezoelectric components have found applications in a variety of fields including energy harvesting, biological and chemical sensing, and telecommunications. The creation of piezoelectric thin films has made possible the implementation of exciting devices that operate at higher frequency (a consequence of the reduction of the thickness of the piezoelectric material) including highly sensitive gravimetric biosensors and acousto-fluidic actuators. However, traditional manufacturing methods for piezoelectrics require a high vacuum, show low deposition rates, involve expensive and complex equipment, and require additional microfabrication processes to achieve the required geometries via patterning and lithography.
Electrohydrodynamic deposition harnesses the electrospray phenomenon to create ultrathin imprints from liquid feedstock. When the electrospray emitter operates in the cone-jet mode, stable jetting of the liquid feedstock allows for the direct writing of structures, thus, eliminating the need for steps for material removal, e.g., mask transfer and etching. In addition, electrohydrodynamic deposition can operate at room temperature without the need for a vacuum and can be scaled-up via electrospray emitter multiplexing.

This project aims to produce piezoelectric thin films suitable for acoustic resonators and actuators via electrospray jetting of nanoparticle-doped liquid feedstock. Initial work revolved around the optimization of the deposition parameters and formulation of the liquid feedstock for the reduction of the printed line’s width and thickness, elimination of the “coffee ring” effect, and analysis of the crystallographic orientation of the films. Current work focuses on improving the film’s homogeneity, increasing the crystal orientation towards a highly oriented film, and its piezoelectric characterization and application as a sensor.