Development of a Multi-Step Exposure Method for Projection-Based Printing System

Projection-based printing has been proven to be an effective way to fabricate user defined complex structures in biomedical applications. Large-scale printing of this process remains a challenge due to the lack of light source with large irradiation area and long transmitting distances. This paper presents a novel method by using multi-step exposure for large-scale parts printing in projection-based printing system. The multi-step exposure method takes the advantage of using a serial of digital masks for exposure incrementally, thus can compensate the printing differences induced by unevenly distributed ultraviolet (UV) intensity. The system setup and printing characterization of the projection-based printing system are studied. The distribution of the UV light power density is measured and the relationship between the printed height and printing parameters are investigated. Then, a multi-step exposure method is proposed and followed by experimental validation. Results showed that the developed printing system with five-step exposure can be used for a relatively large-scale parts printing, and a relatively flat profile can be achieved. Thus, this method provides the potential ability to print large-scale objects for biomedical applications.