Techniques to minimise stair-stepping effect in micro-stereolithography process: A Review

• Published in: Advances in materials and processing technologies (Abingdon, England) England), 2022-10, Vol.8 (4), p.3615-3634
• Main Authors: Bhole, Kiran S., Kale, Bharatbhushan
• Format: Article
• Language: English
• Subjects: micro-electro mechanical systems (mems); micro-fabrication; micro-machining; Micro-stereolithography; stair-stepping effects
• ISSN: 2374-068X; 2374-0698
• DOI: 10.1080/2374068X.2021.1970997

Recently, micro-stereolithography (MSL) has emerged as a promising fabrication process to develop three-dimensional (3D) micro-structures by photocuring 2D layers and stacking the same on the previous one as per the order of curing. Successful fabrications of 3D micro-structures are demonstrated by variants of the MSL. However, stair-stepping effect along the build direction is commonly observed in all the variants of the process due to the inherent characteristics of layer-by-layer fabrication. Various techniques are proposed to minimise stair-stepping effects inherently developed on the lateral surface (surface formed due to stacking of layers) of 3D micro-structures. This paper presents an exhaustive review of all reported techniques on minimisation of stair-stepping effect. The developed techniques are applicable for various types of micro-structures and variants of micro-stereolithography. This review lays the basic guidelines for the development of a process plan based on the micro-structures to be developed and the type of micro-stereolithography process to be deployed. Micro-stereolithography is a promising additive manufacturing process capable to develop high resolution 3D micro-structures in layer-by-layer way. However, due to the inherent nature (layer-by-layer way) of the process stair-stepping effect is commonly observed on the lateral surface of the developed micro-structures. This stair-stepping effect is undesirable on micro-structures to be used in various applications of micro-electromechanical systems. This paper presents an exhaustive review of techniques used for minimisation of stair-stepping effect in micro-stereolithograhy process. Stair-stepping minimisation techniques are classified in two different ways viz; process modification and in-situ approach. These two techniques are discussed in this paper.