Software compensation to improve the Stereolithography fabrication of porous features and porous surface texturing at micro-scale

Abstract

Nano and micro-porous structures exhibit intriguing properties for a wide variety of applications, spanning from the biomedical to sensing. However, their fabrication is a challenge in terms of dimensional accuracy, which affects devices' performance and sensitivity. In this paper, we present a route to enhance the dimensional accuracy of fabrication via Stereolithography (SLA) of porous features at the micro-scale. Using a custom benchmark part, deviations in feature dimensions (micro-pores diameters and depths) were measured by confocal microscopy. Sample characterization and experimental observations allowed the identification of inaccuracy sources (i.e., laser spot size and its compensation on path generation), and a compensation method of the nominal laser spot diameter (85|um) was defined. Implementing such a method results in relevant improvements in dimensional accuracy: 9.8% and 11.3% on full-open pores diameter and depth, respectively. Partially open pores accuracy improvements were 15.8% on diameters and 1.5% on depths. Since machine optical equipment can result in deviations in the actual laser spot diameter from the nominal value, the actual laser beam spot diameter was estimated by printing a test part and adopting this information to adjust a calibration procedure. The measurements revealed that the actual laser beam spot size is 93±8um. The proposed method can be extended for the fabrication of any micro-porous structures.