Recent technological advancement has led to the development of various artificial systems with applications in numerous areas. For instance, the development of advanced artificial systems with the ability to efficiently generate various helical twist deformations and motion has attracted significant attention of researchers. Interestingly, these advances have been inspired by natural and biological systems.
Currently, considering the increasing use of these systems in remote applications, continuous twist movements are highly desirable. Unfortunately, presently available materials are not suitable for offering continuous twist movement in these systems. Therefore, researchers have been looking for alternatives and have identified light-drive continuous twist movements as a promising solution. It will be interesting to link the self-drilling seeds by light-driven continuous twisting to our helical twisting soft matter.
Various photoresponsive materials have been made through the integration of photoisomers into the polymer matrix. However, regardless of the remarkable improvements in multiple based light sources, the development of materials with the ability to efficiently undergo continuous twist movements in single input of light have not been fully explored. Alternatively, crystalline microribbons have exhibited the ability to generate continuous translation movements without multiple light irradiations. To this end, this revelation has compelled researchers to assess the feasibility of using microribbons to generate continuous twist movements.
To this end, Dr. Yifan Zhang, Dr. Yanjun Gong, Professor Yanke Che, and Professor Jincai Zhao at Chinese Academy of Sciences in collaboration with Bo Li and Professor Ren-Min Ma at Peking University explored continuous twist movements of microribbons. By generating a twist at one end of the microribbon, they continuously transmitted the twist to the other microribbon end while at the same time creating coordinated twist motion. In particular, scanning laser irradiation was used to provide single light input. Their research work is currently published in the research journal, Small.
In brief, the research team started by fabricating and assembling low elastic modulus microribbons from asymmetric perylene diimide (PDI) molecules. Secondly, unlike in the previous experiments that were based on molecular motion transmission, the research team employed photoinduced π-stacking distortion to produce the desired continuous twist movements. Eventually, they assessed the possibility of realizing continuous twist movements over microscale systems.
The authors observed that at the initial point, a twist was generated at one end of the ribbon and it was transmitted continuously and rapidly to the other end thus resulting to the continuous twist movement. This was attributed to the incorporation of the π-stacking distortion for twist creation as well as the excellent mechanical properties of the fabricated crystalline microribbon. Additionally, microribbons with relatively high modulus of elasticity did not undergo twisting movement due to insufficient photogenerated stress in the thickness direction.
In summary, the authors successfully demonstrated the twisting process in crystalline microribbons by taking into consideration the vital factors: low elastic modulus and photoinduced π-stacking distortions that were the key elements in overcoming resistance to generate the desired twists. Altogether, the newly introduced principles will pave way for the creation of continuous movements over microscale systems that will further advance numerous applications as light-driven self-propelling machines.
Zhang, Y., Gong, Y., Li, B., Ma, R., Che, Y., & Zhao, J. (2019). Self-Assembled Microribbons: Light-Driven Continuous Twist Movements of Microribbons. Small, 15(7), 1970040.Go To Small