Schematic illustration of direct writing of multi-phase inks into bath support with acoustic focusing to control particle packing and alignment.
Responsive hydrogels that are biocompatible and undergo controlled shape changes in response to a range of stimuli are of interest for microscale soft robotic and biomedical devices. We have developed a new approach for making patterned, multi-material, multi-responsive hydrogels, on a μm to mm scale, which advances existing fabrication methods. Nanolitre aqueous pre-gel droplets were connected through lipid bilayers in predetermined architectures and photopolymerized to yield continuous hydrogel structures. By using this droplet network technology to pattern domains containing temperature-responsive or non-responsive hydrogels, structures that undergo reversible curling were produced. Incorporation of gold nanoparticle-containing domains into the hydrogels leads to light-activated shape change, while domains bearing magnetic particles allowed movement of the structures in a magnetic field. To highlight this technique, a multi-responsive hydrogel that, at one temperature, could be moved through a constriction under a magnetic field; and at a second temperature, could grip and transport a cargo is demonstrated and shown to have potential for impacting current Army’s research programs on bio-enabled 3-D printing.
The overarching objective of this project is to develop advanced 3-D printing technologies for the fabrication of responsive hydrogels that are compatible with synthetic biology for modifying and incorporating bacterial cells [1-3]. These bioenabled constructs will be designed to respond to particular electromagnetic (EM) signatures such as light and magnetic fields with the 3-D printed matrix allowing for tuning response.