Recently, Professor Xin Hongbao and his team from the Institute of Nanophotonics at the School of Physics and Optoelectronic Engineering, Jinan University, in collaboration with Professor Luke. P. Lee from Harvard University, have discovered the orbitalization behavior of microparticles at the mesoscale. This research finding has been published in "Nano Letters."
Illustration of Spontaneous Orbitalization Behavior of Particles at the Mesoscale. Image courtesy of the research team.
The phenomenon of spontaneous orbital motion of objects is widely observed in both extremely small atomic systems at the microscale and vast planetary systems at the macroscale. However, such behavior at the mesoscale is not easily detected. Due to its versatile shape and vibrant colors, soap films at the mesoscale encompass complex physical laws and mechanisms of particle dynamics evolution. Interactions between particles and soap films at the mesoscale are often considered intricate and unpredictable. Previous studies have mainly focused on the disordered behavior of particle ensembles on entire soap films, often requiring external tools or energy to control particle motion, thereby masking the intrinsic interactions between soap films and particles at the mesoscale.
Through extensive experimental research, the research team has observed, for the first time, that particles on soap films with thickness gradients can spontaneously move along specific orbits without any external energy intervention. Simulation calculations and theoretical analysis have revealed that this spontaneous ordered orbital behavior is a result of the strict constraints imposed by the interfacial tension of the soap film on particles in a special wetting state.
Furthermore, the study has found that particles of different sizes and hydrophilicities can spontaneously organize into discrete independent paths and achieve spontaneous sorting on the soap film. Additionally, as the soap film further evolves, the mutual attractive forces between particles on the orbit lead to the formation of low-dimensional particle organizations, such as one-dimensional chains and two-dimensional arrays.
This discovery not only unveils the spontaneous orbitalization behavior of particles at the mesoscale but also opens up new avenues for the manipulation, sorting, and orderly assembly of particles without the need for external energy.
For more information, refer to the related paper: https://doi.org/10.1021/acs.nanolett.4c01840
