Minimal Size of Coffee Ring Structure

Shen, Xiaoying; Ho, Chih‐Ming; Wong, Tak Sing

doi:10.1021/jp912190v

Cited by 315 publications

(334 citation statements)

References 30 publications

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“…The contact line becomes pinned if there is sufficient deposition of solute at the contact line to prevent detachment once the receding contact angle for the substrate is reached. [23] The onset of a coffee ring during drying drops of GO inks is consistent with a model for contact line pinning that compares characteristic time constants for flake aggregation and for the transition from the equilibrium to the receding contact angle.Inkjet printing was used to provide single sessile drops on Si/SiO 2 substrates from aqueous inks containing GO flakes of different sizes. Figure 1 shows the particle size distribution for the eight inks (GO-0-GO-7) used in this study; the mean particle size ranges from 0.68 to 35.9 µm.…”

supporting

confidence: 74%

Controlling Coffee Ring Formation during Drying of Inkjet Printed 2D Inks

Derby

2017

Adv Materials Inter

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There have been several reports of the deposition of graphene dispersions and other 2D materials using inkjet printing. [12,[14][15][16][17][18] Generally, 2D material inks show similar drying behavior to inks made from nanoparticles or nanotubes, i.e. under appropriate drying conditions they show a clear coffee ring with the 2D flakes or 1D tubes arranged at the contact line forming a characteristic ringlike structure. [14,15] Ring formation can be suppressed, for example, by using two solvents [16,17] or adding surfactant and a high boiling point solvent. Recent work by Kim et al. identified both an effect of size and an effect of temperature on the transition to a coffee ring during the drying of suspensions of graphene oxide (GO), [19] with higher drying temperatures suppressing coffee ring formation and a slightly lower critical temperature for ring suppression with inks containing larger GO flakes.Here, we further study the influence of flake size, substrate temperature, and drop size on the morphology of dried droplets of a GO ink. GO is an appropriate model ink because of its ease of dispersal in water and that it is possible to make inks with a wide range of flake sizes showing a common mean flake thickness with little variance. [20] The critical flake size for ring/no ring transition decreases as the substrate (drying) temperature increases. A decrease in the critical flake size also occurs when smaller drop diameters were used. We show that this behavior is governed by hysteresis between the advancing and receding contact angle caused by contact line pinning from heterogeneities in the surface energy or profile (roughness). [21,22] At the onset of drying, the diameter of the drop does not change but the contact angle reduces. The contact line becomes pinned if there is sufficient deposition of solute at the contact line to prevent detachment once the receding contact angle for the substrate is reached. [23] The onset of a coffee ring during drying drops of GO inks is consistent with a model for contact line pinning that compares characteristic time constants for flake aggregation and for the transition from the equilibrium to the receding contact angle.Inkjet printing was used to provide single sessile drops on Si/SiO 2 substrates from aqueous inks containing GO flakes of different sizes. Figure 1 shows the particle size distribution for the eight inks (GO-0-GO-7) used in this study; the mean particle size ranges from 0.68 to 35.9 µm. Sample scanning electron microscopy (SEM) images of the flakes and atomic force microscopy (AFM) height profiles are presented in the Supporting Information showing that the majority of the flakes The morphology of drops of graphene oxide (GO) inks produced by inkjet printing shows a distinctive coffee ring after drying when the mean diameter of the GO is below a critical size. Inks with larger diameter flakes do not show a coffee ring and the transition mean flake diameter decreases as the substrate temperature increases and when the printed drop size decreases. This be...

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supporting

confidence: 74%

Controlling Coffee Ring Formation during Drying of Inkjet Printed 2D Inks

Derby

2017

Adv Materials Inter

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“…When the concentration reduces to 75 fM, the probability reduces to ∼25%. At this concentration, we also found that it is more likely to obtain SERS signals at the edge of the Au nanoparticle aggregate compared with the center region, possibly due to the coffee ring effect (40,41). In the concentration range of subfemtomolar to ∼10 fM, the probability of observing SERS signals is <10% at the edge of the Au nanoparticle aggregate.…”

Section: Resultsmentioning

confidence: 68%

Ultrasensitive surface-enhanced Raman scattering detection in common fluids

Yang

Dai

Stogin

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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608

440

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Detecting target analytes with high specificity and sensitivity in any fluid is of fundamental importance to analytical science and technology. Surface-enhanced Raman scattering (SERS) has proven to be capable of detecting single molecules with high specificity, but achieving single-molecule sensitivity in any highly diluted solutions remains a challenge. Here we demonstrate a universal platform that allows for the enrichment and delivery of analytes into the SERSsensitive sites in both aqueous and nonaqueous fluids, and its subsequent quantitative detection of Rhodamine 6G (R6G) down to ∼75 fM level (10 −15 mol·L −1 ). Our platform, termed slippery liquidinfused porous surface-enhanced Raman scattering (SLIPSERS), is based on a slippery, omniphobic substrate that enables the complete concentration of analytes and SERS substrates (e.g., Au nanoparticles) within an evaporating liquid droplet. Combining our SLIPSERS platform with a SERS mapping technique, we have systematically quantified the probability, p(c), of detecting R6G molecules at concentrations c ranging from 750 fM (p > 90%) down to 75 aM (10 −18 mol·L −1 ) levels (p ≤ 1.4%). The ability to detect analytes down to attomolar level is the lowest limit of detection for any SERS-based detection reported thus far. We have shown that analytes present in liquid, solid, or air phases can be extracted using a suitable liquid solvent and subsequently detected through SLIPSERS. Based on this platform, we have further demonstrated ultrasensitive detection of chemical and biological molecules as well as environmental contaminants within a broad range of common fluids for potential applications related to analytical chemistry, molecular diagnostics, environmental monitoring, and national security.spectroscopy | sensing | SERS | slippery surfaces | nanoparticles

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“…It was recently reported that the time of solvent evaporation and the time of solute diffusion play a crucial role in the "coffee ring" effect. [ 36 ] Morphological investigations by AFM revealed a good intermixing of the polymer and fullerene components for all PCPDTBT:bis-PCBM fi lms obtained from both solvent systems, as depicted in Figure 3c and d . It can be seen that the rmsroughness for the solvent ratio 90/10 ( Figure 3c ) decreased with an increased fullerene content, while for the solvent ratio 80/20 ( Figure 3d ) no trend in the roughness could be observed.…”

Section: Inkjet Printingmentioning

confidence: 84%

Combinatorial Screening of Polymer:Fullerene Blends for Organic Solar Cells by Inkjet Printing

Teichler

Eckardt

Hoeppener

et al. 2010

Advanced Energy Materials

102

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Polymer:fullerene blends were screened in a combinatorial approach using inkjet printing thin film libraries for photovoltaic devices. The application of inkjet printing enabled a fast and simple experimental workflow from film preparation to the study of structure‐property‐relationships with a very high material efficiency. Inkjet printing requires less material for the preparation of thin film libraries in comparison to other dispensing techniques, like spin‐coating. Two polymers (PCPDTBT, PSBTBT) and two fullerene derivatives (mono‐PCBM, bis‐PCBM) were investigated in various blend ratios, concentrations, solvent ratios, and film thicknesses. Morphological and optical properties of the inkjet printed films were investigated and compared with spin‐coated films. This study shows the principle of an experimental setup from solution preparation to film characterization for the combinatorial investigation of large polymer:fullerene libraries.

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Minimal Size of Coffee Ring Structure

Cited by 315 publications

References 30 publications

Controlling Coffee Ring Formation during Drying of Inkjet Printed 2D Inks

Controlling Coffee Ring Formation during Drying of Inkjet Printed 2D Inks

Ultrasensitive surface-enhanced Raman scattering detection in common fluids

Combinatorial Screening of Polymer:Fullerene Blends for Organic Solar Cells by Inkjet Printing

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