Surface-active microrobots can propel through blood faster than inert microrobots

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Microscale Transport

Background:

• Microrobots navigating blood vessels require efficient propulsion methods.
• Blood's high cell volume fraction presents challenges for microrobot movement.
• The optimal swimming strategy for microrobots in blood is not well understood.

Purpose of the Study:

• To numerically investigate microrobot propulsion efficiency in blood.
• To compare the performance of surface-active versus inert microrobots.
• To identify key factors influencing microrobot swimming speed in blood.

Main Methods:

• Numerical simulations were employed to model microrobot dynamics in blood.
• The study analyzed different microrobot types, including squirmers.
• Key parameters such as microrobot size, Capillary number, hematocrit, and magnetic torque were varied.

Main Results:

• Surface-active microrobots (squirmers) demonstrate superior propulsion efficiency in blood compared to inert ones.
• Puller microrobots outperform pusher types at sizes comparable to red blood cells or low Capillary numbers.
• Swimming speed is significantly influenced by hematocrit and applied magnetic torque.
• The squirmer model shows broad applicability, outperforming the Janus squirmer in certain aspects.

Conclusions:

• Surface-active microrobots offer a promising design for efficient propulsion in blood.
• Understanding the interplay between microrobot properties and blood rheology is crucial for medical applications.
• This research provides insights for developing advanced microrobots for targeted drug delivery and diagnostics.