Design and optimization of a microstereolithography 3D printer

Abstract

Stereolithography is a rapid prototyping technology with a hundred-micron-scale resolution based on the process of curing a photopolymer by the interaction of one photon of light with a photoinitiator and/or a photosensitizer. It is a surface based technique where the structure is constructed layer-by-layer. In Mask image Projection approach, the entire cross section is cured by using a Dynamic Mask Generator.

The aim of this thesis was the construction of a Mask Projection Microstereolithography (MPµSL) 3D printer, whose operation is similar to the one mentioned before, but its goal is to print samples with a 5μm resolution. A Digital Micromirror Device (DMD) from a commercial projector was used as Dynamic Pattern Generator, the one will create the desired image on the resin once the UV light from a LED has polymerized it. Moreover, an elevator device, formed by a stepper motor and a linear guide, was used to enable the spread of fresh resin on the top of the already polymerized layer, so it is possible to start the light-induced solidification process of the next.

Once the machine was built, produced samples were analyzed with an electronic (SEM) and an optic microscope to optimize its functioning. With those analysis, it was possible to measure the horizontal resolution of the 3D-printer (4.41〖μm〗^2), while corroborating its correct operation.

One of the most important lines of work would be the development of a device that allows a precise measurement of the distance between the platform and the resin vat, since at this moment this process is done intuitively and in case of using resins with a low depth of penetration, it is a very complicated task