Direction-Switchable Self-Thermophoresis Motor with Chiral Antihelical Resonators

The thermophoresis effect has revolutionized adjustable manipulation based on physical, chemical, and even biomolecular mechanisms. However, traditional self-propelled and thermophoresis devices lack reconfigurability of their motion, hindering the dynamic switching and artificial spatial location of the motors. Through numerical simulation, this paper delves into the underexplored concept of tunable antihelical resonators, which offer rich managing channels on differential optical absorption, thermal gradient, and propulsion. Utilizing a pair of oppositely helical gold nanostructures, we demonstrate the achievement of direction-switchable self-thermophoresis motion, along with artificially controllable forward and backward propulsion as well as the retrace operation. To clarify the mechanism in detail, the chiral circular dichroism related resonant light energy absorption and temperature gradient distribution around an antihelical particle are observed under various circularly polarized light sources. We further elucidate the rapid responses and principles of photothermal propulsion and successfully manipulate photothermal self-propulsion. Additionally, we establish a linear relationship between the laser power and multiphysical quantities such as velocity and force, enabling quantitative modulation in motion. Our work paves the way for chiroptics enabled direction-switchable self-propelled motion and provides a practically rational basis for direction-switchable motors, nanoparticle transport, tracking techniques, and so on.