New research from Ian Wong‘s group at Brown University published in Lab on a Chip and featured in a Technology Networks article shows 3-D printed microfluidic devices with on-demand degradation of substrate materials. Not only does this allow for easy fabrication of complex structures, but also allows for them to be controllably modified ‘on the fly’. The key is in the use of reversibly photopolymerisable hydrogels with ionic cross-linkers. Cross-linkers can then be removed with chelating agents. The stiffness and degradation kinetics are controllable by the choice of metal cation for the ionic cross-linker. Both the sodium alginate ionic cross-linking polymer and chelating agents chosen appear to be biocompatible with the human mammary cells used in the study.
While normally used to directly create the microfluidic structures, the reversible gels were also used in a second approach to create complex moulds that are removed after a second polymer forms around the reversible gel.
The technology may potentially be applied as an adaptive or stimulus responsive material for use in sensing, actuation, drug delivery, cell migration monitoring for wounds or cancer, artificial tissue scaffolding or other applications.