Smart structures and functional devices require coupling of physical properties such as stiffness, damping, conductivity, dielectricity, piezoelectricity, and magnetic properties. Moreover, we require wide range of anisotropic behaviors throughout a structure and device. Although, additive manufacturing provides a platform for printing various geometric features, the conventional printers are limited to small set of materials. We need to customizable 3D printers to print architected microstructures using heterogeneous inks or filaments.
Specially, for functional composites, we study pneumatic-controlled direct ink writing (DIW) printing. The customizable DIW printers can print anisotropic materials using inks from multiple nozzles. Precise control of these ink mixture, printing paths, and speeds enables us to print composites for sensing, processing, and actuation functionalities. We print fiber embedded composites, hydrogels, and LCE to achieve stimuli response to solvents, water, and temperature, respectively. The glass and metallic fibers in elastomeric composites are oriented during printing so that the metamaterial can show directional functions. We also design the anisotropy of LCE by aligning the oligomers by controlling the shear extrusion of nozzle. Additive manufacturing of such logic encoded network is broadly applicable for encoding logic based multistable structures, flexible robotics, and sensor technologies.
Our interests also includes structural composites to rapidly manufacture fiber reinforce composites. Especially, we are studying the frontal polymerization method, an exothermic reaction triggered by an initial stimulus which spontaneously curing the polymer. We aim to develop gradual curing process of this polymers to meet the demand of agile manufacturing and on-site repair works.
