Contact Angle Dependence of the Resonant Frequency of Sessile Water Droplets

Sharp, James S.; Farmer, David John; Kelly, James

doi:10.1021/la201984y

Cited by 88 publications

(85 citation statements)

References 22 publications

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“…For both, typical observables are mode shapes [11,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], resonance frequencies [11,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], and the evolution of surface waves with forcing amplitude [18,23,[29][30][31][33][34][35]. The free surface waves oscillate at the forcing frequency (harmonically) when the forcing acceleration is low.…”

Section: Introductionmentioning

confidence: 99%

Footprint geometry and sessile drop resonance

2017

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In this work, we experimentally examine the resonance of a sessile drop with a square footprint (square drop) on a flat plate. Two families of modal behaviors are reported. One family is identified with the modes of sessile drops with circular footprints (circular drop), denoted as 'spherical modes'. The other family is associated with Faraday waves on a square liquid bath (square Faraday waves), denoted as 'grid modes'. The two families are distinguished based on their dispersion behaviors. By comparing the occurrence of the modes, we recognize spherical modes as the characteristic of sessile drops and grid modes as the constrained response. Within a broader context, we further discuss the resonance modes of circular sessile drops and free spherical drops, and we recognize various modal behaviors as surface waves under different extents of constraint. From these, we conclude that sessile drops resonate according to how wavenumber selection by footprint geometry and capillarity compete. For square drops, a dominant effect of footprint constraint leads to grid modes; otherwise the drops exhibit spherical modes, the characteristic of sessile drops on flat plates. *

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Section: Introductionmentioning

confidence: 99%

Footprint geometry and sessile drop resonance

2017

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“…Droplet vibration has been studied for some time as a means of trying to extract physical properties such as the surface tension and viscosity of fluids [1][2][3][4][5][6][7][8]. Much of the early work in this field concentrated on the study of levitated droplets of single component liquids, whose properties could be extracted using theories based upon the theoretical models developed by Rayleigh [9] and Chandrasekhar [10].…”

Section: Introductionmentioning

confidence: 99%

“…There are, however, a number of challenges in interpreting the drop vibration data for substrate supported drops. Firstly, the presence of a substrate (or pipette) influences the drop shape and has an influence on the vibrational frequency [5,6,8]. Gravity can also play a role in changing the frequencies of vibration if the droplets exceed a critical size.…”

Section: Introductionmentioning

confidence: 99%

Optovibrometry: tracking changes in the surface tension and viscosity of multicomponent droplets in real-time

Harrold

Sharp

2016

Soft Matter

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An instrument was developed for measuring real time changes in the surface tension and viscosity of multicomponent droplets of miscible liquids and other soft materials. Droplets containing glycerol and water were supported on superamphiphobic surfaces and vibrated by applying a short mechanical impulse. Laser light was refracted through the droplets and allowed to fall on the surface of a photodiode. Time dependent variations in the intensity measured by the photodiode during vibration were used to monitor the decay of the droplet oscillations. The frequencies and spectral widths of the droplet vibrational resonances were then obtained from Fourier transforms of these time dependent intensity signals. A recently developed model of droplet vibration was used along with these values and measurements of the drop dimensions to extract the surface tension and viscosity of the drops as they evaporated. Collection of data was automated and values of frequency, spectral width, drop size, surface tension and viscosity were obtained with a time resolution of three seconds over a period of thirty minutes. The values of surface tension and viscosity obtained were shown to be in good agreement with literature values obtained from bulk glycerol/water solutions; thus validating the technique for wider application to other soft matter systems.

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“…In contrast, there have been numerous studies that provide models that attempt to describe the vibrational response of sessile drops [19,[21][22][23][24][25][26]. Perhaps the most simple and intuitive of these models was derived by Noblin et al [23] Noblin's approach considers the surface of the drop as a bath of liquid of finite depth, h, on which standing capillary waves can occur.…”

Section: Introductionmentioning

confidence: 99%

“…A key part of this work involves extending the studies of Noblin et al [23] and Sharp et al [19,24,25] and to include experimental studies and a discussion of how damping effects influence the vibrational properties of pendant liquid drops with sizes smaller than the capillary length of the liquids being studied. on the surface of a silicon photodiode which was attached to a home built amplifier circuit and connected to a computer using a National Instruments USB-6008 data acquisition card.…”

Section: Introductionmentioning

confidence: 99%

Mechanical vibrations of pendant liquid droplets

2015

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Abstract. A simple optical deflection technique was used to monitor the vibrations of microlitre pendant droplets of deuterium oxide, formamide, and 1,1,2,2-tetrabromoethane. Droplets of different volumes of each liquid were suspended from the end of a microlitre pipette and vibrated using a small puff of nitrogen gas. A laser was passed through the droplets and the scattered light was collected using a photodiode.Vibration of the droplets resulted in the motion of the scattered beam and time dependent intensity variations were recorded using the photodiode. These time dependent variations were Fourier transformed and the frequencies and widths of the mechanical droplet resonances were extracted. A simple model of vibrations in pendant/sessile drops was used to relate these parameters to the surface tension, density and viscosity of the liquid droplets. The surface tension values obtained from this method were found to be in good agreement with results obtained using the standard pendant drop technique. Damping of capillary waves on pendant drops was shown to be similar to that observed for deep liquid baths and the kinematic viscosities obtained were in agreement with literature values for all three liquids studied.

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Contact Angle Dependence of the Resonant Frequency of Sessile Water Droplets

Cited by 88 publications

References 22 publications

Footprint geometry and sessile drop resonance

Footprint geometry and sessile drop resonance

Optovibrometry: tracking changes in the surface tension and viscosity of multicomponent droplets in real-time

Mechanical vibrations of pendant liquid droplets

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