self-propulsion
Self-propulsion is the autonomous displacement of nano-, micro- and macroscopic natural and artificial objects, containing their own means of motion.{{Cite journal |last1=Abbott |first1=Nicholas L. |last2=Velev |first2=Orlin D. |title=Active particles propelled into researchers' focus |journal=Current Opinion in Colloid & Interface Science |volume=21 |pages=1–3 |doi=10.1016/j.cocis.2016.01.002|year=2016 }}{{Cite journal |last1=Shapere |first1=Alfred |last2=Wilczek |first2=Frank |date=1987-05-18 |title=Self-propulsion at low Reynolds number |journal=Physical Review Letters |volume=58 |issue=20 |pages=2051–2054 |doi=10.1103/PhysRevLett.58.2051 |pmid=10034637 |bibcode=1987PhRvL..58.2051S}}{{Cite journal |last1=Bico |first1=José |last2=Quéré |first2=David |date=September 2002 |title=Self-propelling slugs |url=https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/selfpropelling-slugs/F059F875CD4A6EA726A781BFF8DD2BEB |journal=Journal of Fluid Mechanics |volume=467 |issue=1 |pages=101–127 |doi=10.1017/s002211200200126x |bibcode=2002JFM...467..101B|url-access=subscription }}{{Cite journal |last1=Ghosh |first1=Ambarish |last2=Fischer |first2=Peer |date=2009-06-10 |title=Controlled Propulsion of Artificial Magnetic Nanostructured Propellers |journal=Nano Letters |volume=9 |issue=6 |pages=2243–2245 |doi=10.1021/nl900186w |pmid=19413293 |bibcode=2009NanoL...9.2243G}}{{Cite journal |last1=Kühn |first1=Philipp T. |last2=de Miranda |first2=Barbara Santos |last3=van Rijn |first3=Patrick |date=2015-12-01 |title=Directed Autonomic Flow: Functional Motility Fluidics |journal=Advanced Materials |volume=27 |issue=45 |pages=7401–7406 |doi=10.1002/adma.201503000|pmid=26467031 }}{{Cite journal |last1=Zhao |first1=Guanjia |last2=Pumera |first2=Martin |date=2012-09-01 |title=Macroscopic Self-Propelled Objects |journal=Chemistry: An Asian Journal |volume=7 |issue=9 |pages=1994–2002 |doi=10.1002/asia.201200206|pmid=22615262 }} Self-propulsion is driven mainly by interfacial phenomena.{{Cite book |title=Physics of Wetting Phenomena and Applications of Fluids on Surfaces |last=Bormashenko |first=Edward |date=2017 |publisher=De Gruyter |isbn=9783110444810 |location=Berlin/Boston, United States |oclc=1004545593}} Various mechanisms of self-propelling have been introduced and investigated, which exploited phoretic effects,{{Cite journal |last1=Moran |first1=Jeffrey L. |last2=Posner |first2=Jonathan D. |date=August 2011 |title=Electrokinetic locomotion due to reaction-induced charge auto-electrophoresis |url=https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/electrokinetic-locomotion-due-to-reactioninduced-charge-autoelectrophoresis/0C3A94529D837E716E2D0C3F76C53F64 |journal=Journal of Fluid Mechanics |volume=680 |pages=31–66 |doi=10.1017/jfm.2011.132 |bibcode=2011JFM...680...31M|url-access=subscription }} gradient surfaces, breaking the wetting symmetry of a droplet on a surface,{{Cite journal|last1=Daniel|first1=Susan|author-link=Susan Daniel|last2=Chaudhury|first2=Manoj K.|last3=Chen|first3=John C.|date=2001-01-26|title=Fast Drop Movements Resulting from the Phase Change on a Gradient Surface|journal=Science|volume=291|issue=5504|pages=633–636|bibcode=2001Sci...291..633D|doi=10.1126/science.291.5504.633|pmid=11158672}}{{Cite journal |last1=Daniel |first1=Susan |last2=Sircar |first2=Sanjoy |last3=Gliem |first3=Jill |last4=Chaudhury |first4=Manoj K. |date=2004-05-01 |title=Ratcheting Motion of Liquid Drops on Gradient Surfaces |journal=Langmuir |volume=20 |issue=10 |pages=4085–4092 |doi=10.1021/la036221a|pmid=15969401 }} the Leidenfrost effect,{{Cite journal |last1=Agapov |first1=Rebecca L. |last2=Boreyko |first2=Jonathan B. |last3=Briggs |first3=Dayrl P. |last4=Srijanto |first4=Bernadeta R. |last5=Retterer |first5=Scott T. |last6=Collier |first6=C. Patrick |last7=Lavrik |first7=Nickolay V. |date=2014-01-28 |title=Asymmetric Wettability of Nanostructures Directs Leidenfrost Droplets |journal=ACS Nano |volume=8 |issue=1 |pages=860–867 |doi=10.1021/nn405585m|pmid=24298880 |citeseerx=10.1.1.642.2490 }}{{Cite journal |last1=Lagubeau |first1=Guillaume |last2=Merrer |first2=Marie Le |last3=Clanet |first3=Christophe |last4=Quéré |first4=David |date=May 2011 |title=Leidenfrost on a ratchet |journal=Nature Physics |volume=7 |issue=5 |pages=395–398 |doi=10.1038/nphys1925 |bibcode=2011NatPh...7..395L|doi-access=free }}{{Cite journal |last1=Bormashenko |first1=Edward |last2=Bormashenko |first2=Yelena |last3=Grynyov |first3=Roman |last4=Aharoni |first4=Hadas |last5=Whyman |first5=Gene |last6=Binks |first6=Bernard P. |date=2015-05-07 |title=Self-Propulsion of Liquid Marbles: Leidenfrost-like Levitation Driven by Marangoni Flow |journal=The Journal of Physical Chemistry C |volume=119 |issue=18 |pages=9910–9915 |doi=10.1021/acs.jpcc.5b01307 |arxiv=1502.04292|bibcode=2015arXiv150204292B }} the self-generated hydrodynamic and chemical fields originating from the geometrical confinements,{{Cite journal |last1=Uspal |first1=W. E. |last2=Popescu |first2=M. N. |last3=Dietrich |first3=S. |last4=Tasinkevych |first4=M. |year=2015 |title=Self-propulsion of a catalytically active particle near a planar wall: from reflection to sliding and hovering |journal=Soft Matter |volume=11 |issue=3 |pages=434–438 |doi=10.1039/c4sm02317j |pmid=25466926 |arxiv=1407.3216 |bibcode=2014SMat...11..434U}} and soluto- and thermo-capillary Marangoni flows.{{Cite journal |last1=Izri |first1=Ziane |last2=van der Linden |first2=Marjolein N. |last3=Michelin |first3=Sébastien |last4=Dauchot |first4=Olivier |year=2014 |title=Self-Propulsion of Pure Water Droplets by Spontaneous Marangoni-Stress-Driven Motion |journal=Physical Review Letters |volume=113 |issue=24 |pages=248302 |doi=10.1103/PhysRevLett.113.248302 |pmid=25541808 |arxiv=1406.5950 |bibcode=2014PhRvL.113x8302I}}{{Cite journal |last1=Nakata |first1=Satoshi |last2=Matsuo |first2=Kyoko |date=2005-02-01 |title=Characteristic Self-Motion of a Camphor Boat Sensitive to Ester Vapor |journal=Langmuir |volume=21 |issue=3 |pages=982–984 |doi=10.1021/la047776o|pmid=15667178 }}{{Cite journal |last1=Frenkel |first1=Mark |last2=Whyman |first2=Gene |last3=Shulzinger |first3=Evgeny |last4=Starostin |first4=Anton |last5=Bormashenko |first5=Edward |date=2017-03-27 |title=Self-propelling rotator driven by soluto-capillary marangoni flows |journal=Applied Physics Letters |volume=110 |issue=13 |pages=131604 |doi=10.1063/1.4979590 |arxiv=1710.09134 |bibcode=2017ApPhL.110m1604F}} Self-propelled system demonstrate a potential as micro-fluidics devices{{Cite journal |last1=Teh |first1=Shia-Yen |last2=Lin |first2=Robert |last3=Hung |first3=Lung-Hsin |last4=Lee |first4=Abraham P. |date=2008-01-29 |title=Droplet microfluidics |journal=Lab on a Chip |volume=8 |issue=2 |pages=198–220 |doi=10.1039/b715524g|pmid=18231657 }} and micro-mixers.{{Cite journal |last1=Nguyen |first1=Nam-Trung |last2=Wu |first2=Zhigang |title=Micromixers—a review |url=http://stacks.iop.org/0960-1317/15/i=2/a=R01?key=crossref.0cc4282f2ae2efd83949fe482c71c476 |journal=Journal of Micromechanics and Microengineering |volume=15 |issue=2 |pages=R1–R16 |doi=10.1088/0960-1317/15/2/r01 |bibcode=2005JMiMi..15R...1N|year=2005 |url-access=subscription }} Self-propelled liquid marbles have been demonstrated.{{-}}