Additive manufacturing of three-dimensional spongy microstructures for a piezoelectric sprayer

Additive manufacturing (AM) of spongy (cancellous) microstructures in the development and application of piezoelectric sprayers was investigated. The structures featuring microfluidic channels were made of solid polylactic acid (PLA) by fused deposition modelling (FDM) designed with a width of 35 mm, a depth of 25 mm, a height of 56 mm, and a cross-layer thickness of 2 mm. In total nine network structures were altered with the line widths (W d) from 300 to 500 μm and the line spacing (S d) from 250 to 400 μm. Then, one piezoelectric plate and another micronozzle array were assembled with the structures as a microactuator. The piezoelectric actuator had a resonance frequency of 107.8 ± 1 kHz, in which it generated microsprays of 3 ml water with a typical volumetric rate of ∼1.1 ml/min. On the basis of FDM with PLA, the works’ dimensional error analysis showed that the minimum AM errors (<5%) between the design and actual dimensions occurred with the W d of 350 μm and the S d of 300–350 μm. In addition, they experimentally discovered anisotropic wettability and different roughness of the PLA layered surfaces, largely concerning the microfluidic performance of the network structures of the piezoelectric sprayer.