Abstract
In this study, tough and conductive hydrogels were printed by 3D printing method. The combination of thermo-responsive agar and ionic-responsive alginate can highly improve the shape fidelity. With addition of agar, ink viscosity was enhanced, further improving its rheological characteristics for a precise printing. After printing, the printed construct was cured via free radical polymerization, and alginate was crosslinked by calcium ions. Most importantly, with calcium crosslinking of alginate, mechanical properties of 3D printed hydrogels are greatly improved. Furthermore, these 3D printed hydrogels can serve as ionic conductors, because hydrogels contain large amounts of water that dissolve excess calcium ions. A wearable resistive strain sensor that can quickly and precisely detect human motions like finger bending was fabricated by a 3D printed hydrogel film. These results demonstrate that the conductive, transparent, and stretchable hydrogels are promising candidates as soft wearable electronics for healthcare, robotics and entertainment.
Highlights
As we know, human skin is soft, self-healable and stretchable, and has the ability to sense subtle external changes
The water molecules penetrate into polymeric hydrogels resulting in an expansion of polymeric networks and a low concentration region of polymeric chains, which leads to mechanical fracture [11]
A tough and conductive hydrogel was developed by 3D printing technology
Summary
Human skin is soft, self-healable and stretchable, and has the ability to sense subtle external changes. High transparency of hydrogels allows these sensory sheets to report electrical signals without impeding optical signals [4] They can behave as tough as elastomers due to recent developments [14,15,16,17], which can monitor large deformation, like finger bending. There are lots of conventional methods to fabricate SA hydrogel constructs including the injection molding method and solution casting method, SA solution has a certain viscosity and its limited flowability leads to a poor dispersion in molds [11] Compared to these conventional methods, 3D printing technology has one main advantage to fabricate customized constructs, which can fit various requirements of wearable sensors applied on different body parts on different humans [17].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
