3D printing UV-curable ionogels with bicontinuous nanostructures
SUSTech researchers have achieved high conductivity without sacrificing the material's 3D printability and mechanical properties
According to the Southern University of Science and Technology (SUSTech) in China, Professor Qi Ge’s research team from the Department of Mechanical and Energy Engineering has developed a UV-curable ionogel with bicontinuous nanostructures to achieve high conductivity without sacrificing its 3D printability and mechanical properties.
The related achievements, entitled ‘Highly Conductive and Stretchable Nanostructured Ionogels for 3D Printing Capacitive Sensors with Superior Performance’, have been published in Nature Communications.
The SUSTech team proposed a photopolymerization-induced microphase separation strategy to prepare bicontinuous ionogels. These ionogels comprise conducting nanochannels intertwined with a cross-linked polymeric framework. The bicontinous structure provides an ordered and continuous channel for ion transport. This approach endows ionogels with high conductivity without sacrificing the printability and mechanical properties. The developed ionogels exhibit high ionic conductivity (over 3 S·m-1), high stretchability (over 1500%), low degree of hysteresis (0.4% at 50% strain), and wide-temperature-range thermostability (-72 ~ 250 ℃).
Owing to low viscosity and high photo-reactivity, the bicontinuous nanostructured ionogels are highly suitable for DLP 3D printing to print highly complex geometries with high resolution. Furthermore, the 3D printed structures with the ionogel exhibit high deformability and high conductivity in a wide temperature range. As shown in Figures 2g and 2h, the 3D printed Octet truss structure is highly deformable at both 100 ℃ and -30 ℃. The high conductivity of the Octet truss structure is maintained at both high and low temperatures.
The high printability of the bicontinuous nanostructured ionogels allows the fabrication of intricate geometries, which can be used to further enhance the capacitance of the EDL capacitive sensors by changing the contacting process between CSN ionogel layer and metal-based electrodes. The researchers printed a hemispherical structure with gradient height for the EDL capacitive sensor, which can significantly boost the sensitivity while simultaneously broadening the pressure-responding linearity.
The 3D printed EDL capacitive sensors have superior sensing performances such as high sensitivity, high linearity, fast dynamic response, excellent cyclic stability, and wide operating temperature range. The printed sensors were integrated into a robotic gripper that can sense grasping signals in a wide temperature range from -30 °C to 150 °C, and collect different combinations of signals while grasping various objects. Furthermore, a pressure sensor array composed of 4 × 4 printed sensors was fabricated for real-time high-resolution pressure mapping.
Ph.D. student Xiangnan He from the Department of Mechanical and Energy Engineering at SUSTech is the first author of this paper. Professor Qi Ge is the corresponding author.
This research was supported by the National Natural Science Foundation of China (NSFC), Key Talent Recruitment Program of Guangdong Province, and the Science, Technology, and Innovation Commission of Shenzhen Municipality.
