4D Printing

In 4D printing, 3D printed structures transform in response to external stimuli. 4D printing requires research on both material and system development for printing. We are working on 3D printed soft actuators and energy harvesters. Because of the scope 3D printing provides for customization and free-form fabrication, energy harvesting in 3D printed wearable devices are garnering interest. Also, 3D printed smart materials for actuation could open avenues for newer applications in robotics and prosthetics. Our research focuses on the 3D printing of piezoelectric/flexoelectric materials and their applications. A lot of piezoelectric materials currently contain hazardous ingredients such as lead (Pb). We are working on green alternatives that can generate electrical energy from mechanical strain.

We are studying advanced functional material that will respond to external excitement. We are exploring an ionic liquid (IL)-based polymer network that can generate mechanical actuation or potential difference with external excitement. IL/polymer network has loosely roaming ions. When an external potential difference is applied in the electrodes, reorientation and polarization happen in the cations and anions. Therefore, bending occurs due to the size difference in cations and anions. Reversely, with applied bending, a potential difference will be generated between the electrodes. This IL/polymer network can also be used as an energy harvester for wearable devices. We are investigating various monomer/oligomer compositions and ionic liquids to develop smart polymers. Phenomena such as piezoelectricity, shape memory, and actuation are being inspected. Modification of the developed material is also an area of study to obtain proper rheology for printing.

We are working on a multi-material printing system with motorized stages and dispensing systems. We are investigating extrusion-based, material jetting-based, stereolithography-based systems for printing. The multi-material printing will be enabled by employing multiple extruders, solenoids, and pressure controllers. The system will retain the functionality of the material and the printed parts. Thermal-curing and photo-curing are being examined to polymerize the printed layers. We developing a program to generate the G-code from the 3D models for motion and extrusion control.