Writable Three-Dimensional Printed Hydrogels Derived from Bingham Fluid Theory for Designable Sensors

Compared with traditional hydrogels, three-dimensional (3D) printed hydrogels can fulfill specific requirements for designable sensors. However, due to the complexity of curing technology and harsh curing conditions, achieving large-scale production and wide-ranging application of 3D printed hydrogels remains challenging. Herein, we successfully proposed an ultrasimple printing strategy for molding 3D printed hydrogels, based on Bingham fluid theory. Results validated the selection of acacia gum (GA) and silicon dioxide (SiO2) with Bingham-like fluid properties as gel media could effectively provide rheological properties and ensure the self-formation of 3D printed hydrogels. Meanwhile, the transient dynamic cross-linking between poly(vinyl alcohol) (PVA) and borax at 25 °C also successfully imparted ideal mechanical strength to 3D printed hydrogels during the printing process. Notably, the prominent printability of the proposed hydrogels also allowed them to be molded into assorted shape sensors, with a gauge coefficient of 2.58, for monitoring strain changes, making it possible to achieve designable sensors. Collectively, the Bingham fluid-based 3D printing technique would hopefully pave the way for specific sensors via 3D printing.