Stress-Based Navigation for Microscopic Robots in Viscous Fluids

TL;DR

This paper explores how microscopic robots can navigate in viscous fluids by analyzing surface stress patterns caused by their motion and nearby boundaries, enabling localization and orientation in tiny vessels.

Contribution

It introduces a method for microscopic robots to estimate their position and orientation using fluid stress patterns, extending stress-based navigation to low Reynolds number environments.

Findings

Estimates are most accurate near vessel walls.

Simple computations enable robots to determine their motion and distance to boundaries.

Applicable to biological vessels like capillaries.

Abstract

Objects moving in fluids experience patterns of stress on their surfaces determined by their motion and the geometry of nearby boundaries. Fish and underwater robots can use these patterns for navigation. This paper extends this stress-based navigation to microscopic robots in tiny vessels, where robots can exploit the physics of fluids at low Reynolds number. This applies, for instance, in vessels with sizes and flow speeds comparable to those of capillaries in biological tissues. We describe how a robot can use simple computations to estimate its motion, orientation and distance to nearby vessel walls from fluid-induced stresses on its surface. Numerically evaluating these estimates for a variety of vessel sizes and robot positions shows they are most accurate when robots are close to vessel walls.