DLP Printing Eutectic Gels Crosslinked by Dopamine-Grafted Nano-Cellulose for Flexible Wearable Devices

Abstract

Eutectic gels have great advantages in the application of flexible wearable electronic devices due to their good stability and flexibility. However, the adhesion properties of current eutectic gels are poor and the processing process is complicated. Based on this, this study proposed a eutectic gel with excellent adhesion properties that can be photocurable for 3D printing. We designed a polymerizable deep eutectic solvent (PDES) using acrylic acid as the main monomer, acrylic acid/choline chloride (AA/ChCl) as the eutectic solvent, and dopamine-grafted cellulose nanocrystals (DC) as the nanoscale crosslinking agent. The introduction of DC endows the gel with a denser hydrogen bond network, which can effectively provide energy dissipation and improve the mechanical properties of the gel. The introduction of mussel-inspired dopamine into the gel network gives the gel good adhesion. The low freezing point and low volatility of PDES give the gel excellent freezing resistance and long-term storage stability. Furthermore, the gel has a sensitivity factor of up to 9.5 (at 0%–900% strain), showing excellent strain sensing performance. In addition, the gel can not only realize the customization of various complex structures through digital light processing (DLP) 3D printing technology, but also the manufactured wearable devices can complete the accurate sensing of various strain signals of the human body. Therefore, the combination of multi-performance compatible eutectic gel materials and photocurable 3D printing technology will provide a new idea for the design and manufacture of flexible wearable devices.