Abstract
Multimaterial additive manufacturing or three-dimensional (3D) printing of hydrogel structures provides the opportunity to engineer geometrically dependent functionalities. However, current fabrication methods are mostly limited to one type of material or only provide one type of functionality. In this paper, we report a novel method of multimaterial deposition of hydrogel structures based on an aspiration-on-demand protocol, in which the constitutive multimaterial segments of extruded filaments were first assembled in liquid state by sequential aspiration of inks into a glass capillary, followed by in situ gel formation. We printed different patterned objects with varying chemical, electrical, mechanical, and biological properties by tuning process and material related parameters, to demonstrate the abilities of this method in producing heterogeneous and multi-functional hydrogel structures. Our results show the potential of proposed method in producing heterogeneous objects with spatially controlled functionalities while preserving structural integrity at the switching interface between different segments. We anticipate that this method would introduce new opportunities in multimaterial additive manufacturing of hydrogels for diverse applications such as biosensors, flexible electronics, tissue engineering and organ printing.
Highlights
Multimaterial additive manufacturing or three-dimensional (3D) printing of hydrogel structures provides the opportunity to engineer geometrically dependent functionalities
Studies have been reported on multimaterial 3D printing by using single nozzle[10,11,12] designs, employing a range of different inks including ceramic pastes, viscoelastic polymers and hydrogels
On the other hand, controlling the switching interface in multimaterial deposition of inks determines the final precision of the process and current methods of deposition based on instant material-switching protocols in single nozzle designs often produce transient regions at the interface composed of an uncontrolled mixture of sequenced inks
Summary
Multimaterial additive manufacturing or three-dimensional (3D) printing of hydrogel structures provides the opportunity to engineer geometrically dependent functionalities. We printed different patterned objects with varying chemical, electrical, mechanical, and biological properties by tuning process and material related parameters, to demonstrate the abilities of this method in producing heterogeneous and multi-functional hydrogel structures. Our results show the potential of proposed method in producing heterogeneous objects with spatially controlled functionalities while preserving structural integrity at the switching interface between different segments We anticipate that this method would introduce new opportunities in multimaterial additive manufacturing of hydrogels for diverse applications such as biosensors, flexible electronics, tissue engineering and organ printing. Recent study by Hardin et al.[11] is an excellent example in which they employed a well-tuned set of parameters by considering ink properties to efficiently control the interface between neighboring segments Their approach is limited by ink’s viscosity and does not seem to be applicable in the case of low viscous materials like hydrogels. The physical properties of inks were considered in tuning process parameters such as process temperature, interfacial features in switching segments and functionality, stability, and integrity of the printed objects
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