Strong charge trapping and bistable electrowetting on nanocomposite fluoropolymer:BaTiO3 dielectrics

Kilaru, Murali K.; Heikenfeld, Jason; Gui, Lin; Mark, J. E.

doi:10.1063/1.2743388

Cited by 44 publications

(33 citation statements)

References 13 publications

(15 reference statements)

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“…As the ions diffuse inward, the effective field at the fluid/dielectric interface can be reduced, generating lower EWFs for a given applied voltage. 13,14 However, upon removal of the applied voltage, the trapped charges dissipate very slowly creating a large residual force as seen in Fig. 10͑a͒ for the 1M NaCl solution.…”

Section: Experimental Ewf Datamentioning

confidence: 94%

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Characterization of electrowetting processes through force measurements

Crane

Mishra

Volinsky

2010

Review of Scientific Instruments

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A new method of characterizing electrowetting is presented. In this method, the electrowetting actuation forces are measured rather than the contact angle. The forces on the liquid are measured by trapping a droplet between a flat nanoindenter tip and the test substrate. When voltage is applied to electrodes in the substrate, lateral and normal forces are exerted on the tip and measured by the nanoindenter transducer. Proper selection of the tip geometry permits direct prediction of the resulting in-plane lateral forces using analytical formulas derived from the Young-Lippmann equation. Experimental results show good agreement with both analytical and numerical predictions. Numerical modeling using SURFACE EVOLVER shows that the lateral forces are relatively insensitive to most alignment errors and that the analytical model is most accurate when the flat tip is close to the substrate. Evaporation of the test liquid can introduce modest errors in long measurements, but compensation methods are presented. As the droplet undergoes almost no movement, the fluid dynamics have minimal impact on the measured forces and transient electrowetting events are readily detected. Experimental results show significant response at frequencies up to 40 Hz. This setup is useful in measuring electrowetting responses at high speeds and in measuring system degradation processes.

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Section: Experimental Ewf Datamentioning

confidence: 94%

“…As such, many aspects of electrowetting behavior are not yet fully understood. These include dielectric charging, 13,14 asymmetric ͑polarity dependent͒ electrowetting responses, 15 and saturation phenomena. [16][17][18] The insulating dielectric layer is commonly coated with a thin hydrophobic coating ͑not shown͒.…”

Section: Introductionmentioning

confidence: 99%

Characterization of electrowetting processes through force measurements

Crane

Mishra

Volinsky

2010

Review of Scientific Instruments

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“…As mentioned above, the threshold voltage is affected not only by the dielectric property but also by the contact angle hysteresis. The contact angle hysteresis of a water drop on the Teflon surface may have different values depending on the deposition methods and materials (Soolaman and Yu 2005;Walker and Shapiro 2006;Berthier et al 2007;Kilaru et al 2007;Li and Mugele 2008). The threshold voltage versus (d/e r ) 1/2 data in Fig.…”

Section: Resultsmentioning

confidence: 97%

Driving characteristics of the electrowetting-on-dielectric device using atomic-layer-deposited aluminum oxide as the dielectric

Chang

Choi

Han

et al. 2009

Microfluid Nanofluid

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Electrowetting on dielectric (EWOD) is useful in manipulating droplets for digital (droplet-based) microfluidics, but its high driving voltage over several tens of volts has been a barrier to overcome. This article presents the characteristics of EWOD device with aluminum oxide (Al 2 O 3 , e r & 10) deposited by atomic layer deposition (ALD), for the first time as the high-k dielectric for lowering the EWOD driving voltage substantially. The EWOD device of the single-plate configuration was fabricated by several steps for the control electrode array of 1 mm 9 1 mm squares with 50 lm space, the dielectric layer of 1,270 Å thick ALD Al 2 O 3 , the reference electrode of 20 lm wide line electrode, and the hydrophobic surface treatment by Teflon-AF coating, respectively. We observed the movement of a 2 ll water droplet in an air environment, applying a voltage between one of the control electrodes and the reference electrode in contact with the droplet. The droplet velocity exponentially depending on the applied voltage below 15 V was obtained. The measured threshold voltage to move the droplet was as low as 3 V which is the lowest voltage reported so far in the EWOD researches. This result opens a possibility of manipulating droplets, without any surfactant or oil treatment, at only a few volts by EWOD using ALD Al 2 O 3 as the dielectric.

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“…Indeed, a similar effect has been seen for electrowetting on dielectric systems in which the electrode material is barium titanate, a piezoelectric material. 21 In this case, bistable electrowetting is possible because of charge trapping in the barium titanate, which leads to compensating charges on the surface of the dielectric. It is suggested that these charges contribute to strong pinning.…”

Section: Resultsmentioning

confidence: 99%

Reversible ultralow-voltage liquid–liquid electrowetting without a dielectric layer

Cousens

Kucernak

2017

Faraday Discuss.

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Electrowetting-on-dielectric devices typically have operating voltages of 10-20 V. A reduction in the operating voltage could greatly reduce the energy consumption of these devices. Herein, fully reversible one-electrolyte electrowetting of a droplet on a solid metal surface is reported for the first time. A reversible change of 29° for an 800 mV step is achieved. The effects of surface roughness, electrolyte composition, electrolyte concentration and droplet composition are investigated. It was found that there is a dramatic dependence of the reversibility and hysteresis of the system on these parameters, contrary to theoretical predictions. When a 3-chloro-1-propanol droplet is used, a system with no hysteresis and a 40° change in angle are obtained.

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Strong charge trapping and bistable electrowetting on nanocomposite fluoropolymer:BaTiO3 dielectrics

Cited by 44 publications

References 13 publications

Characterization of electrowetting processes through force measurements

Characterization of electrowetting processes through force measurements

Driving characteristics of the electrowetting-on-dielectric device using atomic-layer-deposited aluminum oxide as the dielectric

Reversible ultralow-voltage liquid–liquid electrowetting without a dielectric layer

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