Parameter optimization for DLP-printed pNIPAM hydrogels: effects of photoinitiator, crosslinker, light intensity, and exposure time

4D printing has sparked a transformative shift in hydrogel technology by enabling the fabrication of intricate, shape-changing structures with precise temporal control. This innovation holds promise for applications ranging from advanced tissue engineering to responsive drug delivery systems. This study focuses on the manufacturing of poly( N-isopropylacrylamide)-based hydrogels, renowned for their thermo-responsive behaviour. We investigate the influence of composition and parameters on the fabrication of responsive hydrogel structures. We investigate the impact of the amount of photoinitiator (Irgacure 2959), crosslinker (MBA), light intensity, and time of light exposure on the fabrication process, which utilizes an adapted 3D digital light processing printer. We identified the minimum amounts for the analyzed parameters, the effects of excessive quantities, and possible variations to be taken according to different final objectives. Our results offer valuable insights into the design of customizable 4D printable hydrogels, enabling the precise engineering of responsive structures for various applications.