Printing of Woodpile Scaffold Using Fresnel Lens for Tissue Engineering

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Tissue engineering has played a very significant role in the medical field with an ever-growing demand for various tissue donations. One crucial factor is the fabrication of a desirable artificial three-dimensional (3D) tissue scaffold to act as the extracellular matrix (ECM), meeting the complex requirements for specific cell cultures. Existing scaffold fabrication techniques and systems used in constructing extracellular matrix are two-dimensionally limiting, expensive, and time-consuming. For instance, some simple fabrication methods cannot control fabricated structures with morphologies accurately, while others may introduce harmful organic solvents into scaffolds during the fabrication processes. To achieve an optimal scaffold for tissue engineering, we developed a novel 3D printing system capable of printing tissue scaffold structures with improved efficiency. The uniqueness of our system is the transparent diffractive optical elements (DOEs) of linear binary Fresnel lens fabricated to control the luminous intensity distribution. These DOEs of different patterns are arranged in series on a coverslip with each optical element designed to diffact and focus incident light at a particular plane within the device. Coupled with other optical components of the system, 3D woodpile scaffolds were printed in an effective and efficient one-step light exposure process to photo cross-link the polymer solution upon demand. The combination of photo cross-linking and diffractive optical technique incorporated within our system enables the patterning of polymer solutions within seconds, making large-scale fast production not only feasible, but also making printing of complex features simple. With this system, 3D two-layered woodpile structures were successfully fabricated within 3 seconds. While cell toxicity studies showed that the scaffold can be used for tissue engineering.