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Karthik Visvanathan, Farah Shariff, Seow Yuen Yee and Amar S. BasuKarthik Visvanathan, Farah Shariff, Seow Yuen Yee and Amar S. BasuDepartment of Mechanical Engineering, University of Michigan, Ann Arbor, USADepartment of Mechanical Engineering, University of Michigan, Ann Arbor, USA

Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, USAUSA

指導教授：劉承賢 教授指導教授：劉承賢 教授學生：劉景文學生：劉景文

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IntroductionLiterature reviewExperimentResultConclusion/future workReference

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Marangoni FlowThe mass transfer along an interface due to surface tension

gradientLiquid with a high surface tension pulls more strongly on the

surrounding liquidGradient in surface tension will naturally cause the liquid to flow

away from regions of low surface tension

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Example of Marangoni flow - Tears of wineAlcohol has a lower surface

tension than waterThis effect is named after Italian

physicist Carlo MarangoniSurface tension gradient can be

caused by concentration gradient, temperature gradient, etc.

Picture source: www.wikipedia.org keyword : tears of wine

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Floating mini-robot based on thermal Marangoni flow

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Steve H. Suhr et al. designed and built the first controllable water strider robot

Picture source: “Biologically Inspired Miniature Water Strider Robot”

Steve H. Suhr, Yun Seong Song, Sang Jun Lee, and Metin Sitti, Member, IEEE

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Ming Su designed a floating boat by applying drops of organic solvents to the liquid layer

“Liquid mixing driven motions of floating macroscopic objects”APPLIED PHYSICS LETTERS 90, 144102 2007

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A similar work using isopropyl alcohol as a propellant

“Propulsion of microboats using isopropyl alcohol as a propellant”J. Micromech. Microeng. 18 (2008) 067002 (6pp)

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ExperimentWater based mini robots for environmental sensing

applications and/or military applicationsMarangoni flow based on local thermal gradient for

propulsion and steeringCompared with solution based propulsion limited

fuel may be a challengeCompared with propeller based propulsion noise

and vibration may be a challengeIn a macro system, marangoni flow is usually

ignored; but in a micro system, marangoni flow becomes dominant

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ExperimentSix legged design provides three DOF of

movementHigh temperature induces low surface tension,

exerting a tangential force to propel the robot

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ExperimentLift force increases with increasing contact angle

and saturates at contact angle greater than 90°To increase lift force leg of the robot can be

covered with a hydrophobic material

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ExperimentA 10mm x 300μm x 300μm leg with a 2mm x 200μm x 1μm heater

Minimum gap of 10mm between the legs required to prevent temperature gradient from one leg to affect the other

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ExperimentAt 60℃ for each leg

maximum flow velocity 15.3mm/spropulsion force 0.638mN

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ResultA H-shaped structure was constructed to test the

feasibility of the proposed mini-robotH-shaped robot tested in Fluorinert FC 3283

solution

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ResultLinear, clockwise, counter-clockwise motion of

the H-shaped structure demonstratedSpot heated using a soldering iron, the structure

was observed to move from regions of lower surface tension (high temperature region) to higher surface tension (low temperature region)

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Conclusion/future workThis paper reports a novel propulsion mechanism

utilizing a thermal gradient based Marangoni flows

Preliminary experiments demonstrate the feasibility of the proposed propulsion mechanism

The actual proposed device is expected to perform betterhydrophobic material will increase total lift forcepropulsion force can be increased by increasing

temperature of the heater and the number of legs

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Reference Wikipedia “Biologically Inspired Miniature Water Strider Robot” Steve H. Suhr, Yun Seong

Song, Sang Jun Lee, and Metin Sitti, Member, IEEE “Propulsion of microboats using isopropyl alcohol as a propellant” J. Micromech.

Microeng. 18 (2008) 067002 (6pp) “Liquid mixing driven motions of floating macroscopic objects” APPLIED

PHYSICS LETTERS 90, 144102 (2007)

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Thank you for listening