LAUSR

Abstract Electrets have been increasingly investigated for their high piezoelectric sensitivity for sensing and energy harvesting applications, but fabricating complex 3D structures for optimum performance has remained challenging. 3D printing capabilities have likewise become a mature manufacturing technology widely used for end-user customization and rapid prototyping, but limitations on materials and geometries have complicated the incorporation of electroactive structures. In this paper, the first completely 3D printed porous piezoelectret is demonstrated. These samples were structured using standard infill patterns commonly used in 3D printing, allowing easy incorporation with current 3D printing technology. Pores generated by fused-filament fabrication (FFF) are characterized, charged, and the resultant piezoelectret activity measured. Analytical electromechanical models are used to understand and compare the measured charge density and piezoelectric coefficients. The piezoelectric coefficient is found to increase strongly with decreasing infill percentages. An average piezoelectric d33 coefficient of 87 pC N−1 is achieved for 5 % infill samples and is found to be stable for a period of at least 2 weeks, competitive with many other state-of-the-art single-pore piezoelectretic materials. These results provide a first step in using 3D printing techniques to optimize and integrate piezoelectrets into parts, allowing a useful new electroactive functionality for additive manufacturing.