Microstructure Formation by Optofluidic Maskless Lithography Using Fine-tuned Grayscale

We present the high-throughput fabrication technology of free-floating 3D microstructures combining fine-tuned grayscale lithography with optofluidic maskless lithography. Our system simultaneously modulated mask pattern in time phase using Digital Micromirror Device (DMD) in order to generate the different level of ultraviolet (UV) dose for photopolymerization, which causes to produce the different height of microstructure. The time-modulated shape of the UV reflecting on DMD was transferred to photocurable resin flowing through a microfluidic channel as providing high-throughput production of free-floating 3D microstructures. Unlike conventional photolithography has trouble in making grayscale photomask features, our method focuses on direct imaging using 8-bit grayscale for 3D micro-scale structure formations in one step process. Here, we demonstrate diverse 3D microstructures fabrication of gray shades patterns that contain features for multiple or smoothly varying heights.