Electrically tunable window based on microwrinkled ZnO/Ag thin film

Milan Shrestha, Anand Asundi, Gih Keong Lau

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations


Micro-winkling can turn a transparent thin-film of zinc oxide (ZnO) to be âõpaque' that can be reversed by unfolding to restore back to the clear state. This principle was previously used to make a mechanically tunable window device. However, ZnO thin film cannot make a compliant electrode to enable electrical unfolding due to its insulator nature. This paper reports the use of multilayer thin films of 10nm silver (Ag) and 30nm thick ZnO to form a compliant electrode with electrically tunable transmittance. A dielectric elastomer actuator (DEA) with a pair of such compliant Ag/ZnO thin films on both sides of a polyacrylate elastomeric membrane (3M VHB 4910) makes an electrically tunable window device. The DEA without radial compression of the elastomer has wrinkle-free electrode. Hence, it is clear with a 47% in-line transmittance (for 550nm wavelength light). In the wrinkled form, under 10% radial compression, it becomes opaque (with less than 1% transmittance). A voltage induced areal expansion of 10% radial strain enables the electrical unfolding of the initial wrinkles. In addition, this device continues to work after 4000 cycles of unfolding and microwrinkling of Ag/ZnO. The performance of electrically tunable window device is comparable to the existing smart window technologies.

Original languageEnglish
Title of host publicationElectroactive Polymer Actuators and Devices (EAPAD) 2017
EditorsYoseph Bar-Cohen
ISBN (Electronic)9781510608115
StatePublished - 1 Jan 2017
EventElectroactive Polymer Actuators and Devices (EAPAD) 2017 - Portland, United States
Duration: 26 Mar 201729 Mar 2017

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceElectroactive Polymer Actuators and Devices (EAPAD) 2017
CountryUnited States


  • Dielectric elastomer actuator
  • Smart window
  • transparency tuning
  • wrinkles

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