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Yi Z, Huang Z, Lai S, He W, Wang L, Chi F, Zhang C, Shui L, Zhou G. Driving Waveform Design of Electrowetting Displays Based on an Exponential Function for a Stable Grayscale and a Short Driving Time. MICROMACHINES 2020; 11:mi11030313. [PMID: 32188157 PMCID: PMC7142935 DOI: 10.3390/mi11030313] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 11/29/2022]
Abstract
The traditional driving waveform of the electrowetting display (EWD) has many disadvantages, such as the large oscillation of the target grayscale aperture ratio and a long time for achieving grayscale. Therefore, a driving waveform based on the exponential function was proposed in this study. First, the maximum driving voltage value of 30 V was obtained by testing the hysteresis curve of the EWD pixel unit. Secondly, the influence of the time constant on the driving waveform was analyzed, and the optimal time constant of the exponential function was designed by testing the performance of the aperture ratio. Lastly, an EWD panel was used to test the driving effect of the exponential-function-driving waveform. The experimental results showed that a stable grayscale and a short driving time could be realized when the appropriate time constant value was designed for driving EWDs. The aperture ratio oscillation range of the gray scale could be reduced within 0.95%, and the driving time of a stable grayscale was reduced by 30% compared with the traditional driving waveform.
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Affiliation(s)
- Zichuan Yi
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
| | - Zhenyu Huang
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
- Correspondence: ; Tel.: +86-0755-2941-5855
| | - Shufa Lai
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
| | - Wenyao He
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
| | - Li Wang
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
| | - Feng Chi
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
| | - Chongfu Zhang
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
| | - Lingling Shui
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
| | - Guofu Zhou
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
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Li YJ, Echtermeyer D, Cahill BP, Pliquett U. Non-linearity and dynamics of low-voltage electrowetting and dewetting. Phys Chem Chem Phys 2019; 21:18290-18299. [PMID: 31396613 DOI: 10.1039/c9cp02732g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
As an electrically controllable wetting effect, electrowetting on dielectrics (EWOD) is applied in diverse fields including optics, display technology and lab-on-a-chip systems. For the further development of EWOD applications, the reduction of the operation voltage is an essential issue. Recently, a low-voltage EWOD system with a threshold of 2 V was developed. In its sessile drop configuration, an aqueous electrolyte droplet with microliter scaled volume is actuated on an EWOD electrode in oil. The integration of this low-voltage EWOD system into a multiparameter measurement system enables the non-linearity and dynamics of the EWOD system to be online investigated during electrowetting and dewetting. The non-linearity was characterized by the hysteresis in the droplet deformation and that in the thickness variation of an oil layer, which is entrapped between the droplet and the electrode, in the nm range. The dynamics was evaluated with the characteristic time for the droplet deformation upon voltage jumps. This study of electrowetting and dewetting focuses on the conversion efficiency of the electrical energy in the deformation processes.
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Affiliation(s)
- Ying-Jia Li
- SurTec International GmbH, Neuhofstraße 9, 64625, Bensheim, Germany
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Li YJ, Cahill BP. Frequency Dependence of Low-Voltage Electrowetting Investigated by Impedance Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13139-13147. [PMID: 29041777 DOI: 10.1021/acs.langmuir.7b03049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
An electrowetting-on-dielectric (EWOD) electrode was developed that facilitates the use of low alternating voltages (≤5 VAC). This allows online investigation of the frequency dependence of electrowetting by means of impedance spectroscopy. The EWOD electrode is based on a dielectric bilayer consisting of an anodic tantalum pentoxide (Ta2O5) thin film (d = 59.35 nm) with a high relative permittivity (εd = 26.3) and a self-assembled hydrophobic silane monolayer. The frequency dependence of electrowetting was studied using an aqueous μL-sized sessile droplet on the planar EWOD electrode in oil. Experiments using electrochemical impedance spectroscopy and optical imaging indicate the frequency dependence of all three variables in the Young-Lippmann equation: the voltage drop across the dielectric layers, capacitance per unit area, and contact angle under voltage. The electrowetting behavior induced by AC voltages is shown to be well described by the Young-Lippmann equation for AC applications below a frequency threshold. Moreover, the dielectric layers act as a capacitor and the stored electrostatic potential energy is revealed to only partially contribute to the electrowetting.
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Affiliation(s)
- Ying-Jia Li
- Institute for Bioprocessing and Analytical Measurement Techniques e.V. , Rosenhof, 37308 Heilbad Heiligenstadt, Germany
- Department of Physical Chemistry, Georg August University of Göttingen , Tammannstraße 6, 37077 Göttingen, Germany
| | - Brian P Cahill
- Institute for Bioprocessing and Analytical Measurement Techniques e.V. , Rosenhof, 37308 Heilbad Heiligenstadt, Germany
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Zang D, Pauchard L, Shen W. Topical issue on Wetting and Drying: Physics and Pattern Formation. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:27. [PMID: 26920530 DOI: 10.1140/epje/i2016-16027-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 02/24/2016] [Indexed: 06/05/2023]
Affiliation(s)
- Duyang Zang
- Functional Soft Matter and Materials Group, Key Laboratory of Space Applied Physics and Chemistry of the Ministry of Education, School of Science, Northwestern Polytechnical University, 710129, Xi'an, China
| | - Ludovic Pauchard
- Laboratoire FAST, Univ. Paris-Sud, CNRS, Université Paris-Saclay, F-91405, Orsay, France
| | - Wei Shen
- Department of Chemical Engineering, Monash University, Wellington Rd, 3800, Clayton, Vic, Australia
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