China University of Science and Technology proposes composite cold field 3D printing technology for liquid crystal elastomers

Recently, Associate Professor Li Mujun from the School of Engineering Sciences and the Institute of Humanoid Robotics at the University of Science and Technology of China, together with researchers such as Professor Zhang Shiwu, has made significant progress in the field of intelligent material 3D printing. The research team proposed composite cold field 3D printing technology and successfully prepared near ambient temperature responsive liquid crystal elastomers (NAT LCEs) with high orientation sequence parameters and multivariate deformation capabilities. Based on this, an intelligent wristband system with significantly improved heart rate monitoring accuracy was developed. The results were published in the journal ACS Nano under the title "3D Printing of Near Adaptive Responsive Liquid Crystal Elastomers with Enhanced Nematic Order and Pluralized Transformation".

Liquid crystal elastomers, as a new type of intelligent material, have important application value in the fields of soft robots, biomedical devices, and wearable electronics. Traditional liquid crystal elastomers face bottlenecks such as high response temperature (>70 ℃) and limited programmability in manufacturing processes, which severely restrict their practical applications. The development of a new type of liquid crystal elastomer with near ambient temperature response characteristics and precision machining has become a key scientific problem that urgently needs to be overcome in this field. In response to this issue, the research team innovatively proposed a "low-temperature nozzle+cooling platform" composite cold field collaborative control strategy, achieving multiple technological breakthroughs: 1. Precise control of liquid crystal element orientation: maintaining high ink viscosity through a 5 ℃ low-temperature printing environment, inducing highly oriented alignment of liquid crystal elements through shear force, and increasing the orientation sequence parameters by more than 30 times compared to traditional room temperature printing methods. 2. Multivariate deformation programming: achieving reversible deformation of complex structures such as saddles, cones, and English letters. 3. Biocompatible applications: The material responds to temperature and adapts to the human tolerance range, successfully developing an intelligent heart rate monitoring wristband system that can actively adhere to the skin.

Figure 1. Schematic diagram of the working principle of the composite cold field 3D printing system

The structure printed in this study exhibits good environmental adaptability: the disk sample spontaneously forms a saddle shape at room temperature, with an increase in curvature at 10 ℃ and a conical shape at 60 ℃. Gradient programming is achieved through dynamic temperature control, and precise curling deformation is achieved through layered temperature control programming for structures such as "USTC" letters. The research team also explored the application of this technology in the field of precision medicine. The liquid crystal elastic wristband with integrated liquid metal circuit actively adheres to the wrist under PID temperature control, significantly improving measurement accuracy and reducing noise. The performance of 1000 fatigue tests remains unchanged, promoting the development of soft robotics technology, biomedical instruments, and wearable electronic devices.

Li Dongxiao, a master's student in the Department of Precision Machinery and Precision Instruments at the University of Science and Technology of China, and Sun Yuxuan, a postdoctoral fellow, are co first authors of the paper. Associate Professor Li Mujun, Professor Zhang Shiwu, and Postdoctoral Fellow Sun Yuxuan are co corresponding authors. Professor Pan Tingrui from the Suzhou Institute of Advanced Study at the University of Science and Technology of China and Professor Li Weihua from the University of Wollongong in Australia are co authors of the paper. This research has received support from the National Key Research and Development Program of the Ministry of Science and Technology, the Natural Science Foundation of Anhui Province, and the Joint Fund of "New Medicine of University of Science and Technology of China". Some experiments have received support from platforms such as the Micro Nano Research and Manufacturing Center of the University of Science and Technology of China and the Physical and Chemical Science Experimental Center of the University of Science and Technology of China.

Source: opticsky