In recent years, flexible sensors have become popular in many fields such as wearable devices, interactive display devices, stretchable energy harvesting devices, electronic/ionic skins, and soft robots. Stretchable conductors serve as core components of flexible sensors, and their material development and performance studies have attracted researchers' attention. In general, to improve the basic properties of stretchable conductors, efforts are often made in two aspects: material selection and conductor microstructure engineering design.
Among various 3D printing technologies, digital light processing (DLP) has practical application value due to its advantages such as fast processing speed and the ability to prepare products with complex structures with high precision. Although some progress has been made in using DLP to 3D print CIEs, it is often limited by the choice of photosensitive precursors, making it difficult for printed CIEs to have excellent overall performance. By constructing a dynamic network, the photopolymerizable CIEs can be endowed with more comprehensive properties, such as self-healing properties, degradation and recycling capabilities, and working performance under extreme temperatures, which can better meet the needs of the stability of sensing signals in complex environments and green manufacturing needs. To this end, it is imperative to develop CIEs that can be DLP 3D printed and have excellent overall performance.
Recently, the team of Professor Long Yu of Guangxi University developed CIEs with high self-healing efficiency, temperature resistance, degradability and 3D capability. CIEs synthesized by UV curing exhibit good ionic conductivity (0.23 S m-1), and the rich hydrogen bonding interactions in the elastomer network enable the CIEs to have excellent stretchability (565%). Excellent self-healing efficiency (99% at room temperature), degradability, and ability to maintain conductivity and self-healing over a wide temperature range (−23 to 55°C). Subsequently, the team used a new surface projection micro-stereolithography technology (Mofang Precision nanoArch® S140, accuracy: 10 μm) to print CIEs that simulate the microstructure between the epidermis and dermis of human skin, and printed the printed samples Assembled into a highly sensitive ionic skin to monitor tiny deformations in real time. These characteristics indicate that the good comprehensive performance and feasible manufacturing methods make the developed CIEs have broad prospects in the field of flexible electronics.
Conclusion: The research team developed CIEs that are DLP 3D printable and have excellent overall properties. They exhibit inherent ionic conductivity, high transparency, and excellent mechanical properties. Due to the dynamic hydrogen bonds in the elastomer network, the ionic elastomer can achieve efficient autonomous healing (room temperature healing efficiency >99%) and has good temperature weather resistance. In addition, the elastomer also has the ability to degrade in water at room temperature, enabling green post-processing. By using 3D printing technology to prepare ionic elastomers with microstructure, they are assembled into ionic skin to achieve real-time monitoring of tiny pressures. Using 3D printing technology to construct self-healing degradable elastomers provides new insights into developing sensors with comprehensive properties.
Original link:https://doi.org/10.1016/j.cej.2024.149330