Controllable switching between planar and helical flagellar swimming of a soft robotic sperm

Islam S.M. Khalil*, Ahmet Fatih Tabak, Mohamed Abou Seif, Anke Klingner, Metin Sitti

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

24 Citations (Scopus)
21 Downloads (Pure)


Sperm cells undergo a wide variety of swimming patterns by a beating flagellum to maintain high speed regardless of the rheological and physical properties of the background fluid. In this work, we develop and control a soft robotic sperm that undergoes controllable switching between swimming modes like biological sperm cells. The soft robotic sperm consists of a magnetic head and an ultra-thin flexible flagellum, and is actuated using external magnetic fields. We observe that out-of-plane wobbling of the head results in helical wave propagation along the flagellum, whereas in-plane wobbling achieves planar wave propagation. Our theoretical predictions and experimental results show the ability of the soft robotic sperm to change its swimming speed by tuning the beating frequency of its flagellum and the propulsion pattern. The average speed of the soft robotic sperm increases by factors of 2 and 1.2 in fluids with viscosity of 1 Pa.s and 5 Pa.s at relatively low actuation frequencies, respectively, when they switch between planar to helical flagellar propulsion.

Original languageEnglish
Article numbere0206456
Number of pages15
JournalPLoS ONE
Issue number11
Publication statusPublished - 2 Nov 2018
Externally publishedYes


Dive into the research topics of 'Controllable switching between planar and helical flagellar swimming of a soft robotic sperm'. Together they form a unique fingerprint.

Cite this