High tensile properties, wide temperature tolerance, and DLP-printable eutectogels for microarrays wearable strain sensors

Due to good stretchability, conductive gels have significant advantages in the field of manufacturing wearable flexible electronic devices. However, hydrogel-based and ionogel-based conductive materials reported in previous studies are prone to solvent evaporation and leakage, which would seriously affect the gel electromechanical performance in extreme working environments. In addition, how to manufacture gel-based flexible devices with complex structures is also a significant challenge in this field. Based on this, a photocurable 3D-printed eutectogel system was designed in this work. The precursor solution was composed of N-hydroxymethyl acrylamide (NAM), hydroxyethyl methacrylate (HEMA), and DES solvents. The prepared eutectogel had excellent comprehensive properties, such as good transparency (>80 % in the visible region), high tensile performance (up to 648 %), strong mechanical strength (breaking strength up to 938 kPa), electrical conductivity (up to 78 mS/m at 25 ℃), environmental tolerance (-80 ℃ − 60 ℃), and so on. In addition, flexible wearable devices with complex microstructures can be constructed efficiently by DLP printing technology. In the low-pressure detection range (0–––2.5 kPa), the sensitivity of the printed eutectogel-based microarray was 8.78 times higher than that of the block or sheet gel structure, and various weak deformation signals can be timely and accurately detected. Therefore, the combination of photo-cured 3D printing and eutectic gels will provide new possibilities for the development and promotion of intelligent, flexible wearable devices.