A Dielectric Liquid Contact Thermal Switch With Electrowetting Actuation

McLanahan, Aric L. R.; Richards, C. D.; Richards, R. F.

doi:10.1115/imece2010-39269

Cited by 6 publications

(7 citation statements)

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“…In particular, liquid metal microdroplets with a symmetrical spatial structure are useful in developing novel microfluidics engineering devices, advanced functional electronics. In addition, the liquid metal microdroplets with highly monodispersity possess tremendous application potentials in various fields of microfluics actuators, periodic structures and optics devices, for instance, microswitches [10][11][12], micropumps [13], micromixer [14], self-powered acceleration sensor [15], radio frequency resonators [16] and reconfigurable optical diffraction gratings [17][18][19]. Therefore, the fabrication of liquid metal droplets with uniform size is of great significance.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Experimental Validation of Liquid Metal Droplet Formation in a Co-Flowing Capillary Microfluidic Device

Jiang

2020

Micromachines

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A two-phase flow axisymmetric numerical model was proposed to understand liquid metal droplet formation in a co-flowing capillary microfluidics device based on a phase field model. The droplet detachment processes were observed in the experiment and are in good agreement with the simulation method. The effects of the viscosities and flowrates of the continuous phase fluid, interfacial tension as well as the wetting property of the metallic needle against the bulk liquid metal on the droplet formation and production rate were numerically investigated. It was found that the droplet diameter decreased with the increment of the viscosities and flowrates of the outer phase carrier fluid. The dispersed phase fluid with high interfacial tension tended to prolong the time for equilibrium between the viscous drag force and interfacial tension on the liquid–liquid fluid surface, delaying the droplet to be pinched off from the capillary orifice and causing large droplet diameter. Finally, the wetting performance of the metallic needle against the liquid metal was explored. The result indicate that the droplet diameter became less dependent on the contact angle while the size distribution of the liquid metal droplet was affected by their wetting performance. A more hydrophilic wetting performance were expected to prepare liquid metal droplet with more monodispersity. The numerical model and simulation results provide the feasibility of predicting the droplet formation with a high surface tension in a glass capillary microfluidic device.

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Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Experimental Validation of Liquid Metal Droplet Formation in a Co-Flowing Capillary Microfluidic Device

Jiang

2020

Micromachines

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“…Various thermal switch technologies have been studied in the literature including mechanical control of the contact between two surfaces [3], the phase transition of VO 2 between electrical conductor and insulator [4], the use of liquid-vapor phase transition of working fluid [5], and electrowetting of liquid [6][7][8][9]. Nonetheless, the devices are desired to be simple without any moving parts and should be able to control the flow of heat at any temperature to have precise and long-term thermal management for an effective heat recovery.…”

Section: Introductionmentioning

confidence: 99%

Fundamental Evaluation of Thermal Switch Based on Ionic Wind

Yoshida

2019

Energies

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A significant amount of thermal energy (mainly under 200 °C) is wasted in the world. To utilize the waste heat, efficient heat management and thermal switching is required. The basic characteristics of a thermal switch that controls the flow of heat by switching on/off the ionic wind is discussed in this study. The study was conducted through experiments and numerical simulations. A heater made of aluminum block maintained at 100 °C was used as a heat source, and the rate of heat flow to a copper plate placed over it was measured. Ionic wind was induced by corona discharge with a needle placed on the heater. The ratio of heat transfer coefficients was obtained in the range of 3–4, with an energy efficiency of around 10. The heat flux at this condition was approximately 400 W/m2. The numerical simulations indicate that the heat transfer is enhanced by ionic winds, and the results were found to corroborate well with the experimental ones.

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“…In this regard, thermal switches, which alter thermal conductance between ON and OFF states, have attracted considerable attention. In current technologies based on microfabrication, thermal switches are mainly achieved by connecting and breaking two surfaces with the motion of liquid droplets 8 – 10 or solid membranes actuated with electric field 11 or piezoelectric motors 12 . However, these non-monolithic approaches with moving parts often suffer from one or more of the following limitations: materials instability and toxicity, scalability, poor integrability with other devices, low ON/OFF ratio, low speed, and high energy consumption.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Modulation of Thermal Conduction in Vanadium Dioxide Thin Film by Nanostructured Nanogaps

Choe

Suh

et al. 2017

Sci Rep

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Efficient thermal management at the nanoscale is important for reducing energy consumption and dissipation in electronic devices, lab-on-a-chip platforms and energy harvest/conversion systems. For many of these applications, it is much desired to have a solid-state structure that reversibly switches thermal conduction with high ON/OFF ratios and at high speed. Here we describe design and implementation of a novel, all-solid-state thermal switching device by nanostructured phase transformation, i.e., modulation of contact pressure and area between two poly-silicon surfaces activated by microstructural change of a vanadium dioxide (VO2) thin film. Our solid-state devices demonstrate large and reversible alteration of cross-plane thermal conductance as a function of temperature, achieving a conductance ratio of at least 2.5. Our new approach using nanostructured phase transformation provides new opportunities for applications that require advanced temperature and heat regulations.

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A Dielectric Liquid Contact Thermal Switch With Electrowetting Actuation

Cited by 6 publications

References 0 publications

Numerical Simulation and Experimental Validation of Liquid Metal Droplet Formation in a Co-Flowing Capillary Microfluidic Device

Numerical Simulation and Experimental Validation of Liquid Metal Droplet Formation in a Co-Flowing Capillary Microfluidic Device

Fundamental Evaluation of Thermal Switch Based on Ionic Wind

Enhancing Modulation of Thermal Conduction in Vanadium Dioxide Thin Film by Nanostructured Nanogaps

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