Electrostatic control of microstructure thermal conductivity

Supino, R.; Talghader, Joseph J.

doi:10.1063/1.1355302

Cited by 11 publications

(9 citation statements)

References 9 publications

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“…Efforts to control thermal conductivity using nanotechnologies have been made in the past. Supino et al employed a method using electrostatic control of thermal transport through a microstructure in and out of contact with its underlying substrate and achieved thermal conductivity tuning by a factor of 2. Other microscale thermal switches based on active or passive control of mechanical contact have also been proposed and studied. − Philip and co-workers used magnetically polarizable nanofluids to tune thermal conductivity by controlling the linear aggregation length of the nanoparticles.…”

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confidence: 99%

High-Contrast, Reversible Thermal Conductivity Regulation Utilizing the Phase Transition of Polyethylene Nanofibers

2013

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Reversible thermal conductivity regulation at the nanoscale is of great interest to a wide range of applications such as thermal management, phononics, sensors, and energy devices. Through a series of large-scale molecular dynamics simulations, we demonstrate a thermal conductivity regulation utilizing the phase transition of polyethylene nanofibers, enabling a thermal conductivity tuning factor of as high as 12, exceeding all previously reported values. The thermal conductivity change roots from the segmental rotations along the polymer chains, which introduce along-chain morphology disorder that significantly interrupts phonon transport along the molecular chains. This phase transition, which can be regulated by temperature, strain, or their combinations, is found to be fully reversible in the polyethylene nanofibers and can happen at a narrow temperature window. The phase change temperature can be further tuned by engineering the diameters of the nanofibers, making such a thermal conductivity regulation scheme adaptable to different application needs. The findings can stimulate significant research interest in nanoscale heat transfer control.

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confidence: 99%

High-Contrast, Reversible Thermal Conductivity Regulation Utilizing the Phase Transition of Polyethylene Nanofibers

2013

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“…Tunable thermal diodes offer active control of heat flow and therefore are highly attractive for the implementation of thermal circuits and solid-state coolers 1 . Besides various thermal diodes, control of thermal conductivity has been recently demonstrated in telescopically extended multiwall carbon nanotubes 11 ( κ high / κ low = 6.7), and electrostatically actuated etch-released silicon nitride microfilaments 12 ( κ high / κ low = 1.9). However, these intricate devices provide small areas for heat exchange, and are likely prone to fatigue during prolonged operation.…”

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Strain-controlled thermal conductivity in ferroic twinned films

Ding

Ren

et al. 2014

Sci Rep

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Large reversible changes of thermal conductivity are induced by mechanical stress, and the corresponding device is a key element for phononics applications. We show that the thermal conductivity κ of ferroic twinned thin films can be reversibly controlled by strain. Nonequilibrium molecular dynamics simulations reveal that thermal conductivity decreases linearly with the number of twin boundaries perpendicular to the direction of heat flow. Our demonstration of large and reversible changes in thermal conductivity driven by strain may inspire the design of controllable thermal switches for thermal logic gates and all-solid-state cooling devices.

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“…The first approach for thermal control is obtained by changing the duty cycle of a periodic actuation, which was suggested by Supino et al 7 In this approach, microfilaments and the substrate were used as an electrostatic actuator and a pulse voltage was applied to them to snap down microfilaments to the substrate for thermal contact. To obtain linear control of the thermal conductance, the duty cycle of a periodic actuation was changed from 0 to 100%.…”

Section: Adaptive Microbolometersmentioning

confidence: 99%

“…Therefore, typical microbolometers are not able to sense bright and dark signals at the same time without signal clipping or materials degradation. Recently a technology 7,8 has been developed for microbolometers to achieve a larger operational dynamic range using a vertical electrostatic actuator to control the thermal conductance in real time. In this paper, the fabrication of two generations of adaptive microbolometers is explained.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of adaptive microbolometers

Song

Talghader

2004

SPIE Proceedings

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In this paper, the fabrication of microbolometers with electronically controllable responsivity is presented. The first generation devices are built in a standard polysilicon-based micromachining process with HF etch-release and demonstrated with a responsivity that can be tuned over a factor of 50. The responsivity is controlled by applying a voltage between the microbolometer and the substrate. The resulting electrostatic force causes a small portion of the support beam to contact the substrate, which thermally shorts the device at that point. The thermal contact points are defined using curved support beams with residual-stress from a Cr/Au metallization. The lowest portion of the beams contacts the substrate, and the curvature protects the device from full "snapdown," which might induce stiction. The fabrication of the second generation microbolometers based on V O x and silicon nitride materials with a polyimide etch-release is also described. The thermal contact points for these devices are defined by beam mechanics rather than by beam curvature induced by stress, and they actuate at 17 volts. The test array has a fill-factor of 91% for a pixel period of 140µm limited by our photolithography equipment.

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Electrostatic control of microstructure thermal conductivity

Abstract: Articles you may be interested inExtraction of temperature dependent electrical resistivity and thermal conductivity from silicon microwires selfheated to melting temperature

Cited by 11 publications

References 9 publications

High-Contrast, Reversible Thermal Conductivity Regulation Utilizing the Phase Transition of Polyethylene Nanofibers

High-Contrast, Reversible Thermal Conductivity Regulation Utilizing the Phase Transition of Polyethylene Nanofibers

Strain-controlled thermal conductivity in ferroic twinned films

Fabrication of adaptive microbolometers

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