Theoretical model of chirality-induced helical self-propulsion

Area of Science:

• Soft Matter Physics
• Chiral Systems
• Microfluidics

Background:

• Artificial microswimmers can exhibit complex self-propulsion.
• Cholesteric liquid crystal (CLC) droplets in surfactant solutions show spontaneous helical motion.
• The underlying mechanism for this chiral self-propulsion requires further investigation.

Purpose of the Study:

• To develop a phenomenological model for the helical self-propelled motion of CLC droplets.
• To elucidate the key factors governing the emergence of chiral motion in these microswimmers.

Main Methods:

• Constructed a model based on symmetry arguments in chiral systems.
• Used coupled time-evolution equations for droplet velocity, angular velocity, and director field symmetry.
• Investigated bifurcation behaviors between different chiral motion states.

Main Results:

• The model successfully predicts helical and other chiral motions.
• Chiral coupling terms between velocity and angular velocity are crucial.
• Structural anisotropy and nonlinearities in the model equations significantly influence helical motion.

Conclusions:

• The proposed model provides a framework for understanding chiral self-propulsion in CLC microswimmers.
• Symmetry, coupling, anisotropy, and nonlinearity are key to emergent helical motion.
• This work contributes to the design and control of artificial microswimmers.