Fabrication of microstructures using the DMD-based modulating projection printing method

Patterned microstructures of hydrogels have attracted significant attention due to an increasing need for developing scaffolds for tissue engineering, as carriers for drug delivery, and as extracellular matrices for biological studies. However, current tissue engineering approaches lack the flexibility required for developing complex two or three-dimensional (2D/3D) microstructures, which are used to impart suitable cell mechanical microenvironments. In this paper, we present an ultraviolet (UV) light curing method based on a digital mirror device-based modulating projection printing (DMPP) system for fabricating patterned poly(ethylene glycol) diacrylate (PEGDA) hydrogel microstructures. With programmable UV exposure, polymerisation of the PEGDA solution can be induced to create 2D/3D microstructures with high biocompatibility. The main advantage of DMPP is that it is a mask-free method. In addition, the efficiency of the DMPP method is much higher than other methods for patterning PEGDA microstructures. The duration of UV exposure was less than 10 s. In the experiments described below, several types of microstructure arrays have been fabricated. These initial results show that the DMPP method can be used for fabricating highly complex microstructures with controlled accuracy.