The Suspended Thermoreflectance (STR) technique is described in this paper. This optoelectronic measurement tool performs thermal characterization of freestanding micro-/nanoscale materials. STR performs thermal mapping at the submicron level and produces unconstrained thermal conductivity unlike other optical measurement techniques where independent conductivity measurement is not possible due to their reliance on heat capacity.
View Article and Find Full Text PDFFerro hydrophobic particles possess essential properties for controlling the behavior of suspended substances in water. By adjusting the concentration of these particles, the magnetic force within the fluid carrier can be modified, leading to the emergence of distinct flow structures and patterns on the water's surface. This study examines the cloaking phenomenon exhibited by different ferroparticle conditions, employing both experimental and numerical approaches.
View Article and Find Full Text PDFDynamically manipulating droplet motion on hydrophobic surfaces is crucial in various fields, including biomedical, sensing, actuation, and oil-water separation applications. Ferrofluid droplets can be manipulated and controlled using external magnetic forces. The creation of ferrofluids involves multiple procedures that can affect the functionality and stability of droplet manipulation, limiting their use in sustainable applications.
View Article and Find Full Text PDFA novel approach for mitigating environmental dust from hydrophobic surfaces using a water droplet is presented. A sessile droplet is sandwiched between two parallel plates, one of which is moveable and hydrophilic while the other is stationary and hydrophobic. Investigations are conducted into how plate spacing affects the dust mitigation rate and the droplet's level motion.
View Article and Find Full Text PDFAn innovative method is introduced for environmental dust mitigation from a hydrophobic surface by a sessile water droplet. The sessile water droplet is located between two parallel plates having hydrophilic (at the top) and hydrophobic (at the bottom) states. The water droplet is located at the top hydrophilic plate, and the effect of the plate spacing on dust mitigation rate is examined.
View Article and Find Full Text PDFThe sonic excitation of the liquid droplet on a hydrophobic mesh surface gives rise to a different oscillation behavior than that of the flat hydrophobic surface having the same contact angle. To assess the droplet oscillatory behavior over the hydrophobic mesh, the droplet motion is examined under the external sonic excitations for various mesh screen aperture ratios. An experiment is carried out and the droplet motion is recorded by a high-speed facility.
View Article and Find Full Text PDFThe ferro-liquid droplet manipulation on hydrophobic surfaces remains vital for various applications in biomedicine, sensors and actuators, and oil-water separation. The magnetic influence of ferro-liquid droplets on the hydrophobic surface is elucidated. The mechanisms of a newborn droplet formation under the magnetic force are explored.
View Article and Find Full Text PDFWater droplet impact on nanowires/nanowalls' textured hydrophobic silicon surfaces was examined by assessing the influence of texture on the droplet impact dynamics. Silicon wafer surfaces were treated, resulting in closely packed nanowire/nanowall textures with an average spacing and height of 130 nm and 10.45 μm, respectively.
View Article and Find Full Text PDFThe characteristics of droplet impact on hydrophobic surfaces can be altered by introducing surface oscillations. The contact duration, spreading, retraction, and rebounding behaviors of the impacting water droplet are examined at various sonic excitation frequencies of the hydrophobic membrane. Membrane oscillation and droplet behavior are analyzed by utilizing a high-speed camera.
View Article and Find Full Text PDFWater droplet rolling motion over the hydrophobized and optically transparent micro-post array surfaces is examined towards dust removal pertinent to self-cleaning applications. Micro-post arrays are replicated over the optically transparent polydimethylsiloxane (PDMS) surfaces. The influence of micro-post array spacing on droplet rolling dynamics is explored for clean and dusty surfaces.
View Article and Find Full Text PDFA water droplet rolling and spinning in an inclined hydrophobic wedge with different wetting states of wedge plates is examined pertinent to self-cleaning applications. The droplet motion in the hydrophobic wedge is simulated in 3D space incorporating the experimental data. A high-speed recording system is used to store the motion of droplets in 3D space and a tracker program is utilized to quantify the recorded data in terms of droplet translational, rotational, spinning, and slipping velocities.
View Article and Find Full Text PDFRolling liquid droplets are of great interest for various applications including self-cleaning of surfaces. Interfacial resistance, in terms of pinning and shear rate, has a critical role in droplet rolling dynamics on hydrophobic surfaces. Lowering the interfacial resistance requires reducing the droplet wetting length and droplet fluid contact area on hydrophobic surfaces.
View Article and Find Full Text PDFUnidirectional and stabilize droplet rolling over hydrophobic surfaces is critical for self-cleaning applications of large areas. Introducing minute size channels on hydrophobic surfaces in the droplet rolling direction can minimize droplet wobbling and enables unidirectional rolling. The droplet rolling behavior over an inclined hydrophobic surface having a minute size channel is investigated.
View Article and Find Full Text PDFPolycarbonate sheets are optically transparent and have the potential to be used as one of the cover materials for PV applications. Solution treatment of polycarbonate surfaces enables to create surface texture topology giving rise to a hydrophobic state, which is favorable for self-cleaning applications. In the present study, hydrophobization of polycarbonate surface is investigated via crystallization of surface by a one-step process.
View Article and Find Full Text PDFEnvironmental effects such as dust mitigation can amplify the spread of viruses via inhaling infected dust particles. Infusion and the spreading rate of human saliva over the dust particles can play a critical role in contiguous virus spread. In the present study, mechanical and chemical interactions of human saliva with environmental dust particles are considered.
View Article and Find Full Text PDFWater droplet impacting on a slanted dusty hydrophobic surface is examined in relation to dust mitigation from surfaces. Impacting droplet characteristics including droplet spreading/retraction rates, slipping length, and rebound heights are analyzed via high-speed recording and a tracker program. The environmental dust characteristics in terms of size, shape, elemental composition, and surface free energy are evaluated by adopting the analytical methods.
View Article and Find Full Text PDFSelf-cleaning of surfaces becomes challenging for energy harvesting devices because of the requirements of high optical transmittance of device surfaces. Surface texturing towards hydrophobizing can improve the self-cleaning ability of surfaces, yet lowers the optical transmittance. Introducing optical matching fluid, such as silicon oil, over the hydrophobized surface improves the optical transmittance.
View Article and Find Full Text PDFCost effective dust mitigation from surfaces is one of the challenges in various sectors. The reduction of dust adhesion on surfaces plays a vital role for dust mitigation from surfaces under the gravitational influence. Creating an avalanche effect on dusty surfaces improves the dust mitigation rate and provides an effective cleaning process.
View Article and Find Full Text PDFDust repelling from transparent polyvinyl chloride film surface via sonic excitation is examined and dynamics of repelled (inflight) dust particles are analyzed. An experimental rig is designed and built to assess the vibrational characteristics of the polyvinyl chloride film at different frequencies of sonic excitation. A high speed recording system and tracking program are utilized monitoring and evaluating the dynamics of the inflight particles.
View Article and Find Full Text PDFWater droplet cleaning of a dusty hydrophobic surface is examined. Environmental dust are used in the experiments and cloaking velocity of a dust layer by a droplet fluid is measured and hemi-wicking conditions for the dust layer are analyzed adopting the pores media wick structure approach. A droplet motion on dusty and inclined hydrophobic surface is analyzed using a high speed digital imaging system.
View Article and Find Full Text PDFMitigation of environmental dust from surfaces becomes one of the challenges for maintaining the optical characteristics of surfaces. Dust repelling from hydrophobic and hydrophilic surfaces under vibrational excitation is investigated and the percentage of dust repelled from surfaces is evaluated. The characteristics of the dust particles are examined and dust adhesion on surfaces under molecular forces (van der Walls) is explored.
View Article and Find Full Text PDFWettability of a droplet liquid on a dusty hydrophobic plate is considered and the fluid infusion into the dust layer is studied pertinent to dust removal from the hydrophobic surfaces rolling/sliding droplets. Influence of droplet hydrostatic pressure on the fluid infusion into dust layer is also investigated towards exploring the dust removal mechanisms. Environmental dust characteristics are evaluated and their interface with the droplet fluid is assessed.
View Article and Find Full Text PDFCarbonated water droplets can ease the difficulties faced by distilled water droplets mitigating dust particles from hydrophobic surfaces. Rising of CO bubbles in carbonated water droplets and their interaction with the flow structure, created by Marangoni and buoyancy possessions, in droplets are investigated. Spreading and infusion (cloaking) of carbonated water on dust surfaces are analyzed, and the rate at which bubbles formed inside the carbonated water droplet, as placed on a dusty hydrophobic surface, is examined.
View Article and Find Full Text PDFDust mitigation from surfaces remains essential, particularly for the efficient operation of energy harnessing devices. Although various dust removal methods have been introduced, the self-cleaning method is favorable because of the cost-effective cleaning process. Dust mitigation from surfaces by water droplets, mimicking nature, is fruitful because it involves low-cost operations.
View Article and Find Full Text PDFThe motion of a water droplet in a hydrophobic wedge fixture was examined to assess droplet rolling and spinning for improved dust mitigation from surfaces. A wedge fixture composed of two inclined hydrophobic plates had different wetting states on surfaces. Droplet rolling and spinning velocities were analyzed and findings were compared with the experiments.
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