Multiphoton lithography of mechanically and functionally tunable hydrogels
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As one of the few 3D microfabrication techniques available to researchers, multiphoton lithography (MPL) has generated considerable interest in the scientific community. By allowing researchers to localize photochemistry to a femtoliter volume, MPL has permitted the fabrication of intricate, 3D microstructures from a range of materials, including protein hydrogels. MPL can be used to fabricate functional hydrogels on the scale of 100 μm, with features on the order of 1 μm. This dissertation examines existing MPL techniques to discover ways in which current processes can be modified to produce hydrogel products that are more useful for biomedical applications like tissue engineering. A new material is introduced that enables the fabrication of fully unconstrained hydrogel microstructures. In this context, A structure can be classified as “unconstrained” when it is free to translate and rotate without hindrance in three dimensions, and is not attached to the substrate or any other structure. New processes are demonstrated that permit the fabrication of larger MPL hydrogels without sacrificing feature resolution. This allows the fabrication of millimeter-scale, high aspect ratio structures with features smaller than 10 μm. Methods are described for tuning and measuring the mechanical properties of MPL-fabricated hydrogels, and ways of tuning the functional properties of the hydrogels are also examined.