Work

Microwheels on microroads: Enhanced translation on topographic surfaces

Year: 2019

Type: article

Abstract: Microbot locomotion is challenging because of the reversible nature of microscale fluid flow, a limitation that can be overcome by breaking flowfield symmetry with a nearby surface. We have used this strategy with rotating wheel-shaped microbots, μwheels, that roll on surfaces leading to enhanced propulsion and fast translation speeds. Despite this, studies to date on flat surfaces show that μwheels roll inefficiently with significant slip. Taking inspiration from the mathematics of roads and wheels, here we demonstrate that μwheel velocities can be significantly enhanced by changing microroad topography. In this, we observe that periodic bumps in the road can be used to enhance the traction between μwheels and nearby walls. While continuous μwheel rotation with slip is observed on flat surfaces, a combination of rotation with slip and non-slip flip occurs when μwheels roll upon surfaces with periodic features, resulting in up to four-fold enhancement in translation velocity. The surprisingly fast rolling speed of μwheels on bumpy roads can be attributed to the hydrodynamic coupling between μwheels and road surface features, allowing non-slip rotation of entire wheels along one of their stationary edges. This road/wheel coupling can also be used to enhance μwheel sorting and separation where the gravitational potential energy barrier induced by topographic surfaces can lead to motion in only one direction and to different rolling speeds between isomeric wheels, allowing one to separate them not based on size but on symmetry.

Source: Science Robotics

DOI: 10.1126/scirobotics.aaw9525

Authors: Tao Yang, Andrew Tomaka, Tonguc O. Tasci, Keith B. Neeves, Ning Wu, David W. M. Marr

Institutions: Colorado School of Mines, University of Colorado Anschutz, University of Colorado Denver

Language: English

Topic: Micro and Nano Robotics

Subfield: Condensed Matter Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Aeronautics and Space Administration, National Institute of Allergy and Infectious Diseases, National Institute of Neurological Disorders and Stroke

Awards: Magnetically propelled microwheels for rapid thrombolysis in small arteries, Airborne delivery of microbots for chemical and mechanical attack of pulmonary biofilms, COLLOIDAL PARTICLES ARE TECHNOLOGICALLY IMPORTANT MATERIALS WITH APPLICATIONS RANGING FROM CONSUMER PRODUCTS TO PLASMONIC METAMATERIALS TO DRUG DELIV, Bead-Based Approach for Combined Mechanical and Pharmacological Treatment of Acut