Optical Micromirror Actuation using Thermocapillary Effect in Microdroplets

Dhull, Rakesh K.; Puchades, Ivan; Fuller, Lynn; Lu, Yen‐Wen

doi:10.1109/memsys.2009.4805553

Cited by 5 publications

(7 citation statements)

References 10 publications

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“…Dhull and coworkers proposed a method to actuate micromirrors by inducing thermocapillarity in a droplet on a solid surface [ 209 ]. The microplate has been placed on top of a microdroplet and voltage has been supplied to the quarter-ring-shaped heaters to produce temperature gradient between two sides of the droplet, inclining it toward cold side and hence tilting the microplate on top of it.…”

Section: Device Applicationsmentioning

confidence: 99%

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Thermocapillarity in Microfluidics—A Review

2016

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This paper reviews the past and recent studies on thermocapillarity in relation to microfluidics. The role of thermocapillarity as the change of surface tension due to temperature gradient in developing Marangoni flow in liquid films and conclusively bubble and drop actuation is discussed. The thermocapillary-driven mass transfer (the so-called Benard-Marangoni effect) can be observed in liquid films, reservoirs, bubbles and droplets that are subject to the temperature gradient. Since the contribution of a surface tension-driven flow becomes more prominent when the scale becomes smaller as compared to a pressure-driven flow, microfluidic applications based on thermocapillary effect are gaining attentions recently. The effect of thermocapillarity on the flow pattern inside liquid films is the initial focus of this review. Analysis of the relation between evaporation and thermocapillary instability approves the effect of Marangoni flow on flow field inside the drop and its evaporation rate. The effect of thermocapillary on producing Marangoni flow inside drops and liquid films, leads to actuation of drops and bubbles due to the drag at the interface, mass conservation, and also gravity and buoyancy in vertical motion. This motion can happen inside microchannels with a closed multiphase medium, on the solid substrate as in solid/liquid interaction, or on top of a carrier liquid film in open microfluidic systems. Various thermocapillary-based microfluidic devices have been proposed and developed for different purposes such as actuation, sensing, trapping, sorting, mixing, chemical reaction, and biological assays throughout the years. A list of the thermocapillary based microfluidic devices along with their characteristics, configurations, limitations, and improvements are presented in this review.

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Section: Device Applicationsmentioning

confidence: 99%

“…Copyright 2009, IEEE. Reprinted, with permission, from [ 209 ], R. Dhull, I. Puchades, L. Fuller, and Y. Lu, “Optical Micromirror Actuation using Thermocapillary Effect in Microdroplets”, in Processings of IEEE 22nd International Conference on Micro Electro Mechanical Systems (MEMS 2009), 2009, pp. 995–998.…”

Section: Device Applicationsmentioning

confidence: 99%

Thermocapillarity in Microfluidics—A Review

2016

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“…Compared with solid-state micromirrors, liquid-based thermal micromirrors are easy to fabricate without additional complicated MEMS processes. In 2009, in the report from Dhull et al, a liquid microdroplet was dropped on a Teflon surface which adhered to a silicon chip; the droplet could generate a motion by heating one of its sides [ 17 ], as shown in Figure 28 a. Due to the thermocapillary effect, a mirror plate was tilted by the droplet, achieving a maximum angle of 6.5° at 30 V with a frequency of 7 Hz, as shown in Figure 28 b,c.…”

Section: Electrothermal Micromirrorsmentioning

confidence: 99%

“…The free side of a bimorph cantilever can achieve a large out-of-plane deflection when changing the bimorph’s temperature [ 16 ]. Thermocapillary and thermo-pneumatic actuators have also been employed in scanning micromirrors [ 17 , 18 ]. Furthermore, electrothermal actuators combined with electrostatic or electromagnetic actuators have been explored to take their respective advantages while overcome their drawbacks [ 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Review of Electrothermal Micromirrors

Tang

et al. 2022

Micromachines

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Electrothermal micromirrors have become an important type of micromirrors due to their large angular scanning range and large linear motion. Typically, electrothermal micromirrors do not have a torsional bar, so they can easily generate linear motion. In this paper, electrothermal micromirrors based on different thermal actuators are reviewed, and also the mechanisms of those actuators are analyzed, including U-shape, chevron, thermo-pneumatic, thermo-capillary and thermal bimorph-based actuation. Special attention is given to bimorph based-electrothermal micromirrors due to their versatility in tip-tilt-piston motion. The exemplified applications of each type of electrothermal micromirrors are also presented. Moreover, electrothermal micromirrors integrated with electromagnetic or electrostatic actuators are introduced.

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“…The same behavior has been seen when droplets or bubbles are flowing inside a carrier liquid in a closed microplatform. Not only was this concept used to direct emulsions along certain paths [ 140 ], but it also led to the fabrication of on-chip elements such as valves [ 141 ], pumps [ 142 ], traps [ 143 ], microcapacitors [ 144 ], micromirrors [ 145 ], etc. Later on, Basu realized thermocapillary actuation by fabricating arrays of microheater elements on a suspended plate on top of the carrier liquid bath ( Figure 21 ) [ 146 ].…”

Section: Microfluidics Inspired By Taxismentioning

confidence: 99%

Microfluidic Devices Developed for and Inspired by Thermotaxis and Chemotaxis

Karbalaei

Cho

2018

Micromachines

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Taxis has been reported in many cells and microorganisms, due to their tendency to migrate toward favorable physical situations and avoid damage and death. Thermotaxis and chemotaxis are two of the major types of taxis that naturally occur on a daily basis. Understanding the details of the thermo- and chemotactic behavioral response of cells and microorganisms is necessary to reveal the body function, diagnosing diseases and developing therapeutic treatments. Considering the length-scale and range of effectiveness of these phenomena, advances in microfluidics have facilitated taxis experiments and enhanced the precision of controlling and capturing microscale samples. Microfabrication of fluidic chips could bridge the gap between in vitro and in situ biological assays, specifically in taxis experiments. Numerous efforts have been made to develop, fabricate and implement novel microchips to conduct taxis experiments and increase the accuracy of the results. The concepts originated from thermo- and chemotaxis, inspired novel ideas applicable to microfluidics as well, more specifically, thermocapillarity and chemocapillarity (or solutocapillarity) for the manipulation of single- and multi-phase fluid flows in microscale and fluidic control elements such as valves, pumps, mixers, traps, etc. This paper starts with a brief biological overview of the concept of thermo- and chemotaxis followed by the most recent developments in microchips used for thermo- and chemotaxis experiments. The last section of this review focuses on the microfluidic devices inspired by the concept of thermo- and chemotaxis. Various microfluidic devices that have either been used for, or inspired by thermo- and chemotaxis are reviewed categorically.

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Optical Micromirror Actuation using Thermocapillary Effect in Microdroplets

Cited by 5 publications

References 10 publications

Thermocapillarity in Microfluidics—A Review

Thermocapillarity in Microfluidics—A Review

Review of Electrothermal Micromirrors

Microfluidic Devices Developed for and Inspired by Thermotaxis and Chemotaxis

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