Spiral-shaped soft-swimmer with propulsion force by geometry change

Abstract

This paper describes a spiral-shaped soft-swimmer with propulsion force change by geometry change. In nature, microorganism has spiral-shaped flagella. The softness of flagella is important to realize intellectual swimming such as velocity control. Spiral-shaped soft-swimmers were continuously formed by using a bevel-tip capillary. Soft-swimmers were rotating by applying rotational magnetic fields that were generated by two axial electromagnetic coils. We confirmed that propulsion force of soft-swimmers with different pitches by tracking the motion of surrounding microbeads (f_mag = 5 Hz, 20 mT). Type 1 (p = 418 μm) was no propulsion force, and propulsion force of Type 2 (p = 1638 μm) was larger than Type 3 (p = 2640 μm). This result indicates that the relevant pitch size is necessary for efficient propulsion. We believe that our micro-swimmer could pave the way to various microscale biochemical applications such as autonomous soft-robots and soft micro-probes for intricate environment.