TY  - JOUR
AU  - Ahmed, Daniel
AU  - Sukhov, Alexander
AU  - Hauri, David
AU  - Rodrigue, Dubon
AU  - Maranta, Gian
AU  - Harting, Jens
AU  - Nelson, Bradley J.
TI  - Bioinspired acousto-magnetic microswarm robots with upstream motility
JO  - Nature machine intelligence
VL  - 3
IS  - 2
SN  - 2522-5839
CY  - [London]
PB  - Springer Nature Publishing
M1  - FZJ-2021-04841
SP  - 116 - 124
PY  - 2021
AB  - The  ability  to  propel  against  flows,  that  is,  to  perform  positive  rheotaxis,  can  provide  exciting  opportunities  for  applications  in  targeted  therapeutics  and  non-invasive  surgery.  So  far  no  biocompatible  technologies  exist  for  navigating  microparticles  upstream  when  they  are  in  a  background  fluid  flow.  Inspired  by  many  naturally  occurring  microswimmers—such  as  bacteria,  spermatozoa  and  plankton—that  utilize  the  no-slip  boundary  conditions  of  the  wall  to  exhibit  upstream  propulsion,  here  we  report  on  the  design  and  characterization  of  self-assembled  microswarms  that  can  execute  upstream  motility  in  a  combina-tion  of  external  acoustic  and  magnetic  fields.  Both  acoustic  and  magnetic  fields  are  safe  to  humans,  non-invasive,  can  pen-etrate  deeply  into  the  human  body  and  are  well-developed  in  clinical  settings.  The  combination  of  both  fields  can  overcome  the limitations encountered by single actuation methods. The design criteria of the acoustically induced reaction force of the microswarms, which is needed to perform rolling-type motion, are discussed. We show quantitative agreement between experi-mental data and our model that captures the rolling behaviour. The upstream capability provides a design strategy for deliv-ering  small  drug  molecules  to  hard-to-reach  sites  and  represents  a  fundamental  step  towards  the  realization  of  micro-  and  nanosystem navigation against the blood flow.
LB  - PUB:(DE-HGF)16
C6  - 34258513
UR  - <Go to ISI:>//WOS:000607597200002
DO  - DOI:10.1038/s42256-020-00275-x
UR  - https://juser.fz-juelich.de/record/903117
ER  -