Additive fabrication techniques such as three-dimensional (3D) printing are receiving growing interest from a diverse range of fields due to their ability to quickly produce complex 3D objects. However, new applications of hydrogels such as soft robotics and cartilage tissue scaffolds require hydrogels with enhanced mechanical performance, which has stimulated an investigation into how hydrogels may be made electrically conducting, tougher and more enduring. Moreover, the parallel development of these materials and suitable 3D fabrication techniques has accelerated the advancement of many technologies including bionic implants, sensors, controlled release systems and soft robotics.
The understanding of how to marry these recent advances in materials (e.g. tough and/or electrically conducting hydrogels) with manufacturing (3D printing of hydrogels) for the purpose of building smart hydrogel materials is incomplete.
In this presentation I will describe our approach to 3D printing gels (consisting of the edible biopolymers gellan gum and gelatin) that is based on optimizing the rheological conditions for additive manufacturing with a 4th generation 3D-Bioplotter. Gellan gum and gelatin are versatile ingredients in well-known food products such as the commercially available product Aeroplane Jelly. The crucial aspect to facilitate printing is that these gels can be prepared in a “one-pot” synthesis approach. The resulting gels based on a combination of ionically cross-linked gellan gum and covalently cross-linked gelatin networks exhibit suitable mechanically (1 MPa tensile stress at failure) and electrical (1 S/cm electrical conductivity) characteristics. The origin of the mechanical robust and electrical behavior will be discussed in detail. In addition, I will demonstrate that the gel’s mechanical and electrical characteristics vary with the concentration of the charge carriers. Finally, I will present our results on 3D printed (electronic) hydrogel devices for future application in bionics and soft robotics.