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Studies of Electric-Field Induced Surface Instabilities Using Confocal Microscopy.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Studies of Electric-Field Induced Surface Instabilities Using Confocal Microscopy./
Author:	Charoen-Rajapark, Pavida.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
Description:	194 p.
Notes:	Source: Dissertations Abstracts International, Volume: 83-02, Section: B.
Contained By:	Dissertations Abstracts International83-02B.
Subject:	Engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28497321
ISBN:	9798534680225

Studies of Electric-Field Induced Surface Instabilities Using Confocal Microscopy.
Charoen-Rajapark, Pavida.

Studies of Electric-Field Induced Surface Instabilities Using Confocal Microscopy. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 194 p.

Source: Dissertations Abstracts International, Volume: 83-02, Section: B.

Thesis (Ph.D.)--Harvard University, 2021.

This item must not be sold to any third party vendors.

Dielectric elastomer actuators (DEAs) are electro-mechanical transducers that can convert an electrical input into mechanical work. They have found many applications including soft robotics and tunable windows. The latter operate by applying an electric potential to the DEA, inducing surface morphological changes that scatter light and reduce in-line transmittance. Tunable windows operate in two regimes of behavior. In the low electric field regime, inhomogeneous surface deformations of the elastomer form, which cause local variations in optical refraction and changes light transmittance. In the high electric field regime, an array of pits forms on the surface by a nucleation and growth mechanism. The pits also scatter light. Much of the theoretical understanding of the aforementioned instability and growth mechanism has arisen from scaling arguments and perturbation analysis, built upon experimental investigations of the surface instabilities. While most prior studies have focused on only the superficial features of the instabilities, minimal effort has been devoted to imaging their shape at higher fields, much larger the initial surface instability. My thesis describes observations, using fluorescence confocal microscopy, of the three-dimensional shape evolution in the post-instability regime, as the applied voltage is increased. These reveal a complex series of previously unknown, and reversible, geometric instabilities. I also performed a scaling analysis showing that the energetics of the system are dominated by the electrostatic and elastic energies with minimal surface energy contributions.Finally, I investigated the electromechanical behavior of the fundamental building block of tunable windows, which is the deformation associated with charging a single wire on the surface of a dielectric elastomer. I imaged the surface and volumetric deformations induced by the wire as it was actuated by an increasing potential difference. This serves as a starting point for further theoretical and experimental investigations of the interactions between multiple, percolating wire electrodes.

ISBN: 9798534680225Subjects--Topical Terms:

586835
Engineering.
Subjects--Index Terms:

Dielectric elastomer actuators

Studies of Electric-Field Induced Surface Instabilities Using Confocal Microscopy.
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100 1 $a Charoen-Rajapark, Pavida. $0 (orcid)0000-0003-3805-5296 $3 3683628
245 1 0 $a Studies of Electric-Field Induced Surface Instabilities Using Confocal Microscopy.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2021
300 $a 194 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-02, Section: B.
500 $a Advisor: Clarke, D.
502 $a Thesis (Ph.D.)--Harvard University, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Dielectric elastomer actuators (DEAs) are electro-mechanical transducers that can convert an electrical input into mechanical work. They have found many applications including soft robotics and tunable windows. The latter operate by applying an electric potential to the DEA, inducing surface morphological changes that scatter light and reduce in-line transmittance. Tunable windows operate in two regimes of behavior. In the low electric field regime, inhomogeneous surface deformations of the elastomer form, which cause local variations in optical refraction and changes light transmittance. In the high electric field regime, an array of pits forms on the surface by a nucleation and growth mechanism. The pits also scatter light. Much of the theoretical understanding of the aforementioned instability and growth mechanism has arisen from scaling arguments and perturbation analysis, built upon experimental investigations of the surface instabilities. While most prior studies have focused on only the superficial features of the instabilities, minimal effort has been devoted to imaging their shape at higher fields, much larger the initial surface instability. My thesis describes observations, using fluorescence confocal microscopy, of the three-dimensional shape evolution in the post-instability regime, as the applied voltage is increased. These reveal a complex series of previously unknown, and reversible, geometric instabilities. I also performed a scaling analysis showing that the energetics of the system are dominated by the electrostatic and elastic energies with minimal surface energy contributions.Finally, I investigated the electromechanical behavior of the fundamental building block of tunable windows, which is the deformation associated with charging a single wire on the surface of a dielectric elastomer. I imaged the surface and volumetric deformations induced by the wire as it was actuated by an increasing potential difference. This serves as a starting point for further theoretical and experimental investigations of the interactions between multiple, percolating wire electrodes.
590 $a School code: 0084.
650 4 $a Engineering. $3 586835
650 4 $a Applied physics. $3 3343996
650 4 $a Materials science. $3 543314
650 4 $a Polymers. $3 535398
650 4 $a Carbon fibers. $3 685794
650 4 $a Nanowires. $3 576100
650 4 $a Evolution. $3 532919
650 4 $a Electrodes. $3 629151
650 4 $a Oxidation. $3 714629
650 4 $a Glass substrates. $3 3683629
650 4 $a Wire. $3 3681397
650 4 $a Experiments. $3 525909
650 4 $a Elastomers. $3 698991
650 4 $a Electric fields. $3 880423
650 4 $a Microscopy. $3 540544
650 4 $a Ratios. $3 3561161
650 4 $a Three dimensional imaging. $3 1084804
650 4 $a Advisors. $3 3560734
650 4 $a Deformation. $2 lcstt $3 3267001
650 4 $a Morphology. $3 591167
653 $a Dielectric elastomer actuators
653 $a Electrically tunable windows
653 $a Surface instability
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710 2 $a Harvard University. $b Engineering and Applied Sciences - Engineering Sciences. $3 3184097
773 0 $t Dissertations Abstracts International $g 83-02B.
790 $a 0084
791 $a Ph.D.
792 $a 2021
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28497321