Precise switching control of liquid crystalline microgears driven by circularly polarized light.

Liquid crystalline molecules carrying photopolymerizable end groups absorb photon energy via a two-photon process, enabling the photofabrication of 3D structures. In this work, we prepared microgears with different heights and tooth lengths. These birefringent microgears can be induced to rotate by circularly polarized light. Here, we demonstrate that the use of phase plate for switching between left- and right-handed polarization reverses the optically induced rotation while maintaining the same rotational frequency. Due to the precise switching control, these birefringent microgears have advantages over previous microrotors that are fabricated from non-birefringent light-curing resins.