Self-motile swimmers: Ultrasound driven spherical model

Area of Science:

• Acoustics
• Fluid Dynamics
• Micro-robotics

Background:

• Autonomous propulsion is crucial for micro- and molecular-scale machines.
• Ultrasound acoustic fields offer a potential mechanism for generating propulsion.
• Understanding the physics of acoustic radiation forces is key to designing self-motile devices.

Purpose of the Study:

• To investigate ultrasound acoustic driven self-motile swimmers for autonomous propulsion.
• To analytically determine the conditions under which acoustic fields can generate propulsion.
• To calculate swimming velocity and identify optimal operating conditions for these micro-swimmers.

Main Methods:

• Analytical investigation of acoustic radiation forces generated by oscillating surfaces.
• Modeling of a spherical swimmer geometry in a host medium.
• Application of low Reynolds number conditions to derive swimming velocity.
• Frequency-dependent analysis of propulsion based on design parameters.

Main Results:

• An asymmetric acoustic field induces a non-zero acoustic radiation force, enabling propulsion.
• The swimming velocity is frequency-dependent and a function of design parameters.
• Optimum operating conditions for propulsion were determined analytically.

Conclusions:

• The study demonstrates the feasibility of ultrasound acoustic driven self-motile swimmers.
• This methodology paves the way for micro- and molecular-sized self-propulsive machines.
• Potential applications span engineering, medicine, and biology.