DLP printing PEG-based gels with high elasticity and anti-dryness for customized flexible sensors

Abstract

Hydrogels, due to their exceptional flexibility, elasticity, and stretchability, are extensively utilized in numerous fields, particularly in the use of flexible wearable devices. However, the prevalent issues of solvent evaporation and limited environmental tolerance in the application of hydrogels significantly constrain their utilization in the field of flexible sensing. In this study, we designed a special organic gel, utilizing PEG as the solvent instead of water and Zr⁴⁺ as the physical cross-linking agent, to facilitate the formation of a steady copolymer network (P(AA-co-HEA)/PEG) that exhibits excellent mechanical properties, such as high fracture stress (1 MPa) and low hysteresis (<7%), as well as good adhesion ability (30 kN/m²) and good solvent evaporation resistance. Moreover, the addition of Zr⁴⁺ and Zn²⁺ not only enhanced the mechanical properties of the gel but also endowed it with good electrical conductivity. The conductive gels are capable of accurately distinguishing various deformations (10−250% tensile strain) and successively outputting reliable electrical signals with good durability. Most importantly, the gel can be utilized to fabricate a variety of complex structures via digital light processing (DLP) 3D printing technology. In summary, this work introduces a novel approach for the development of highly stable flexible wearable devices, which has the potential to expand the applications of PEG-based gel materials.