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Majumder S, Basavaraj MG, Satapathy DK. Soft colloidal monolayers with reflection symmetry through confined drying. NANOSCALE ADVANCES 2024:d4na00542b. [PMID: 39139712 PMCID: PMC11317906 DOI: 10.1039/d4na00542b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Accepted: 07/17/2024] [Indexed: 08/15/2024]
Abstract
Colloidal monolayers serve as fundamental building blocks in fabricating diverse functional materials, pivotal for surface modifications, chemical reactivity, and controlled assembly of nanoparticles. In this article, we report the formation of colloidal monolayers generated by drying an aqueous droplet containing soft colloids confined between two hydrophilic parallel plates. The analysis of the kinetics of evaporation in this confined mode showed that: (i) for a significant portion of the drying time, the drops adopt a catenoid configuration; (ii) in the penultimate stage of drying, the catenoid structure undergoes division into two daughter droplets; (iii) the three-phase contact line remains pinned at a specific location while it continuously slips at all other locations. The interplay between interface-assisted particle deposition onto the solid substrate and the time evolution of particle concentration within the droplet during evaporation results in unique microstructural features in the deposited patterns. Notably, these deposit patterns exhibit reflection symmetry. The microstructural features of the dried deposits are further quantified by calculating the particle number density, inter-particle separation, areal disorder parameter, and bond orientational order parameter. The variation of these parameters for deposits formed under different conditions, such as by altering the spacing between parallel plates and the concentration of microgel particles in the droplet, is discussed.
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Affiliation(s)
- Sanjib Majumder
- Soft Material Laboratory, Department of Physics, IIT Madras Chennai-600036 India
- Centre for Soft and Biological Matter, IIT Madras Chennai-600036 India
| | - Madivala G Basavaraj
- PECS Lab, Department of Chemical Engineering, IIT Madras Chennai-600036 India
- Centre for Soft and Biological Matter, IIT Madras Chennai-600036 India
| | - Dillip K Satapathy
- Soft Material Laboratory, Department of Physics, IIT Madras Chennai-600036 India
- Centre for Soft and Biological Matter, IIT Madras Chennai-600036 India
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2
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Kwon YW, Ahn DB, Park YG, Kim E, Lee DH, Kim SW, Lee KH, Kim WY, Hong YM, Koh CS, Jung HH, Chang JW, Lee SY, Park JU. Power-integrated, wireless neural recording systems on the cranium using a direct printing method for deep-brain analysis. SCIENCE ADVANCES 2024; 10:eadn3784. [PMID: 38569040 PMCID: PMC10990281 DOI: 10.1126/sciadv.adn3784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 02/27/2024] [Indexed: 04/05/2024]
Abstract
Conventional power-integrated wireless neural recording devices suffer from bulky, rigid batteries in head-mounted configurations, hindering the precise interpretation of the subject's natural behaviors. These power sources also pose risks of material leakage and overheating. We present the direct printing of a power-integrated wireless neural recording system that seamlessly conforms to the cranium. A quasi-solid-state Zn-ion microbattery was 3D-printed as a built-in power source geometrically synchronized to the shape of a mouse skull. Soft deep-brain neural probes, interconnections, and auxiliary electronics were also printed using liquid metals on the cranium with high resolutions. In vivo studies using mice demonstrated the reliability and biocompatibility of this wireless neural recording system, enabling the monitoring of neural activities across extensive brain regions without notable heat generation. This all-printed neural interface system revolutionizes brain research, providing bio-conformable, customizable configurations for improved data quality and naturalistic experimentation.
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Affiliation(s)
- Yong Won Kwon
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - David B. Ahn
- Department of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Young-Geun Park
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Enji Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Dong Ha Lee
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Sang-Woo Kim
- Department of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Kwon-Hyung Lee
- Ulsan Advanced Energy Technology R&D Center, Korea Institute of Energy Research (KIER), Ulsan 44776, Republic of Korea
| | - Won-Yeong Kim
- Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 03772, Republic of Korea
| | - Yeon-Mi Hong
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Chin Su Koh
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Hyun Ho Jung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Jin Woo Chang
- Department of Neurosurgery, Korea University Anam Hospital, Seoul 02841, Republic of Korea
| | - Sang-Young Lee
- Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 03772, Republic of Korea
| | - Jang-Ung Park
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
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3
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Hidalgo RBP, Molina-Courtois JN, Carreón YJP, Díaz-Hernández O, González-Gutiérrez J. Dried blood drops on vertical surfaces. Colloids Surf B Biointerfaces 2024; 234:113716. [PMID: 38160474 DOI: 10.1016/j.colsurfb.2023.113716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 10/03/2023] [Accepted: 12/13/2023] [Indexed: 01/03/2024]
Abstract
The analysis of structures in dried droplets has made it possible to detect the presence and conformational state of macromolecules in relevant biofluids. Therefore, the implementation of novel drying strategies for pattern formation could facilitate the identification of biomarkers for the diagnosis of pathologies. We present an experimental study of patterns formed by evaporating water-diluted blood droplets on a vertical surface. Three significant morphological features were observed in vertical droplet deposits: (1) The highest concentration of non-volatile molecules is consistently deposited in the lower part of the droplet, regardless of erythrocyte concentration. (2) The central region of deposits decreases rapidly with hematocrit; (3) At high erythrocyte concentrations (36-40% HCT), a broad coating of blood serum is produced in the upper part of the deposit. These findings are supported by the radial intensity profile, the relative thickness of the crown, the aspect ratio of the deformation, the relative area of the central region, and the Entropy of the Gray Level Co-occurrence Matrix Entropy (GLCM). Moreover, we explore the pattern formation during the drying of vertical blood drops. We found that hematocrit concentration has a significant impact on droplet drying dynamics. Finally, we conducted a proof-of-concept test to investigate the impact of vertical droplet evaporation on blood droplets with varying lipid concentrations. The results revealed that it is possible to differentiate between deposits with normal, slightly elevated, and moderately elevated lipid levels using only the naked eye.
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Affiliation(s)
- Roxana Belen Pérez Hidalgo
- Facultad de Ciencias en Física y Matemáticas Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, México
| | - Josías N Molina-Courtois
- Facultad de Ciencias en Física y Matemáticas Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, México
| | - Yojana J P Carreón
- Facultad de Ciencias en Física y Matemáticas Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, México; CONACyT, México City, México
| | - Orlando Díaz-Hernández
- Facultad de Ciencias en Física y Matemáticas Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, México
| | - Jorge González-Gutiérrez
- Facultad de Ciencias en Física y Matemáticas Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, México.
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Hariharan S, Thampi SP, Basavaraj MG. Kinetics of evaporation of colloidal dispersion drops on inclined surfaces. SOFT MATTER 2023; 19:6213-6223. [PMID: 37382057 DOI: 10.1039/d3sm00375b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Evaporation of colloidal dispersion drops leaves a deposit pattern where more particles are accumulated at the edge, popularly known as the coffee-ring effect. Such patterns formed from dried sessile drops are azimuthally symmetric. When the substrate is inclined, the symmetry of the patterns is altered due to the influence of gravity. This is reflected in the changes in (i) pinning/depinning dynamics of the drop, (ii) the strength of the evaporation-driven flows, and (iii) ultimately, the lifetime of the drop. We present a systematic investigation of the kinetics of evaporation of particle-laden drops on hydrophilic inclined solid substrates. The angle of inclination of the substrate (ϕ) is varied from 0° to 90°. The temporal analysis of the drop shape profile is carried out to unearth the contribution of different processes to kinetics of evaporation of drops on inclined surfaces. The influence of particle concentration, drop volume, and angle of inclination on the kinetics of evaporation and the resulting deposit patterns are discussed.
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Affiliation(s)
- Sankar Hariharan
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India.
| | - Sumesh P Thampi
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India.
| | - Madivala G Basavaraj
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India.
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5
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Katre P, Banerjee S, Balusamy S, Sahu KC. Stability and Retention Force Factor for Binary-Nanofluid Sessile Droplets on an Inclined Substrate. Ind Eng Chem Res 2023. [DOI: 10.1021/acs.iecr.3c00160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Affiliation(s)
- Pallavi Katre
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana India
| | - Sayak Banerjee
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana India
| | - Saravanan Balusamy
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana India
| | - Kirti Chandra Sahu
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana India
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6
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Issakhani S, Jadidi O, Farhadi J, Bazargan V. Geometrically-controlled evaporation-driven deposition of conductive carbon nanotube patterns on inclined surfaces. SOFT MATTER 2023; 19:1393-1406. [PMID: 36723256 DOI: 10.1039/d2sm01431a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Controllable accumulation of carbon nanotubes in self-assembly techniques is of critical importance in smart patterning and printed electronics. This study investigates how inclining the substrate and inhibiting the droplet spreading by sharp solid edges can affect the droplet contact angle and pinning time to improve the electrical conductivity and uniformity of the deposited patterns. Rectangular and circular pedestals were employed to investigate the effect of geometry on the deposition characteristics and to incorporate the gravitational effect by varying the substrate inclination angle. The results indicate that confining the droplet contact line to remain pinned to the pedestal edge can significantly alter the width, uniformity, and precision of the deposited patterns. These improvements correspond to the enhancement of the droplet pinning time (due to the edge effect) and to the further increase of the local evaporation rate near the contact line (due to the droplet elevation). By conducting experiments on different rectangular pedestals with varying solid-liquid interfacial areas and comparing their deposition characteristics, a rectangular pedestal with specific dimensions is selected in terms of pattern consistency and material usage efficiency. It is also shown that higher inclination angles further increase the deposited line accumulation density. Combining confinement and inclination techniques yields promising deposited patterns with high consistency and low resistivity, ranging from 8.75 kΩ mm-1 to a minimum of 0.63 kΩ mm-1 for a 3 × 6 mm2 rectangular pedestal.
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Affiliation(s)
- Shervin Issakhani
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Omid Jadidi
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Jafar Farhadi
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Vahid Bazargan
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
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7
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Yang XY, Li GH, Huang X, Yu YS. Wetting of aqueous sodium dodecyl sulfate droplets on polydimethylsiloxane surfaces during evaporation. Colloids Surf A Physicochem Eng Asp 2023. [DOI: 10.1016/j.colsurfa.2022.130342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Chatterjee S, Murallidharan JS, Bhardwaj R. Size-Dependent Dried Colloidal Deposit and Particle Sorting via Saturated Alcohol Vapor-Mediated Sessile Droplet Spreading. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6128-6147. [PMID: 35507639 DOI: 10.1021/acs.langmuir.2c00492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We experimentally and theoretically investigate a distinct problem of spreading, evaporation, and the associated dried deposits of a colloidal particle-laden aqueous sessile droplet on a surface in a saturated alcohol vapor environment. In particular, the effect of particle size on monodispersed suspensions and efficient self-sorting of bidispersed particles have been investigated. The alcohol vapor diffuses toward the droplet's curved liquid-vapor interface from the far field. The incoming vapor mass flux profile assumes a nonuniform pattern across the interface. The alcohol vapor molecules are adsorbed at the liquid-vapor interface, which eventually leads to absorption into the droplet's liquid phase due to the miscibility. This phenomenon triggers a liquid-vapor interfacial tension gradient and causes a reduction in the global surface tension of the droplet. This results in a solutal Marangoni flow recirculation and spontaneous droplet spreading. The interplay between these phenomena gives rise to a complex internal fluid flow within the droplet, resulting in a significantly modified and strongly particle-size-dependent dried colloidal deposit. While the smaller particles form a multiple ring pattern, larger particles form a single ring, and additional "patchwise" deposits emerge. High-speed visualization of the internal liquid-flow revealed that initially, a ring forms at the first location of the contact line. Concurrently, the Marangoni flow recirculation drives a collection of particles at the liquid-vapor interface to form clusters. Thereafter, as the droplet spreads, the smaller particles in the cluster exhibit a "jetlike" outward flow, forming multiple ring patterns. In contrast, the larger particles tend to coalesce together in the cluster, forming the "patchwise" deposits. The widely different response of the different-sized particles to the internal fluid flow enables an efficient sorting of the smaller particles at the contact line from bidispersed suspensions. We corroborate the measurements with theoretical and numerical models wherever possible.
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Affiliation(s)
- Sanghamitro Chatterjee
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | | | - Rajneesh Bhardwaj
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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9
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Katre P, Balusamy S, Banerjee S, Sahu KC. An Experimental Investigation of Evaporation of Ethanol-Water Droplets Laden with Alumina Nanoparticles on a Critically Inclined Heated Substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4722-4735. [PMID: 35377666 DOI: 10.1021/acs.langmuir.2c00306] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We experimentally investigate the evaporation of water-ethanol binary sessile droplets loaded with alumina nanoparticles on a critically inclined heated surface and compare it to the no-loading condition. In contrast to a droplet of pure fluids, several distinct and interesting phenomena observed in a binary-nanofluid droplet on a critically inclined substrate are reported for the first time. The critical angle at which a droplet begins to slide increases for ethanol-rich binary droplets up to 0.6 wt % nanoparticle loading. The critical angle for binary droplets also increases as the substrate temperature increases and as the ethanol concentration decreases for modest loading conditions. It is observed that the advancing side of a binary droplet is pinned in both the loading and no-loading scenarios, whereas the receding side is pinned in the loading case but shrinks continuously in the no-loading case. The pinning effect caused by nanoparticles results in a larger perimeter and surface area for the nanoparticle-laden droplets, enhancing the evaporation rates and significantly decreasing the lifetime of the nanoparticle-containing droplets compared to the no-loading case. Increasing the ethanol percentage in the binary droplet placed on an inclined substrate produces complex thermosolutal Marangoni convection, which becomes more affluent in the case of nanoparticles loading than the no-loading condition. The radial symmetry of the circular coffee ring structure observed on a horizontal surface is shattered in the inclined case because the droplet elongates and preferentially deposits toward the advancing side of the triple line due to the action of the body force. Despite its fundamental nature, the present study can contribute to understanding many practical applications.
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Affiliation(s)
- Pallavi Katre
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana, India
| | - Saravanan Balusamy
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana, India
| | - Sayak Banerjee
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana, India
| | - Kirti Chandra Sahu
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502 284, Telangana, India
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10
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Logesh Kumar P, Thampi SP, Basavaraj MG. Patterns from drops drying on inclined substrates. SOFT MATTER 2021; 17:7670-7681. [PMID: 34319344 DOI: 10.1039/d1sm00714a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The coffee ring effect results from the migration of particles in a drying particle laden drop and their subsequent deposition at the three phase contact line. The evaporative flux during the drying of sessile drops and the spatial distribution of particles in the coffee ring patterns exhibit azimuthal symmetry. It is possible to break this symmetry with the help of gravity by simply manipulating the inclination of the substrate on which the colloidal droplet undergoes drying. However, the effect of particle size, substrate wettability and inclination angle on the extent of asymmetry in the spatial distribution of particles over the deposit patterns has not been explored and is the subject of the current work. Our experiments on the drying of aqueous dispersions of polystyrene particles show that (i) asymmetry in the deposition of particles is observed irrespective of the diameter of the dispersed particles in the drying drop (ii) the degree of asymmetry increases with a decrease in wettability of the drop on the substrate and (iii) it is a non-monotonic function of the inclination angle of the substrate. These results indicate the possibility of additional particle transport mechanisms working in tandem with evaporation driven capillary flows and demand further investigation of the physics of pattern formation in drops drying on oriented substrates.
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Affiliation(s)
- P Logesh Kumar
- Department of Chemical Engineering, Polymer Engineering and Colloid Sciences Laboratory, Indian Institute of Technology Madras, Chennai-600036, India.
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Kim JY, Gonçalves M, Jung N, Kim H, Weon BM. Evaporation and deposition of inclined colloidal droplets. Sci Rep 2021; 11:17784. [PMID: 34493801 PMCID: PMC8423794 DOI: 10.1038/s41598-021-97256-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/19/2021] [Indexed: 11/09/2022] Open
Abstract
Colloidal droplets on flat solid substrates commonly leave symmetric ring-like deposits due to coffee-ring flows during evaporation. On inclined substrates, droplet shapes may become asymmetric by gravity. On this basis, it is not clear how their evaporation dynamics and final deposits are changed depending on inclination. Here we explore evaporation and deposition dynamics of colloidal droplets on inclined substrates, mainly by controlling colloidal particle size, substrate inclination, and relative humidity, which are crucial to gravitational intervention and evaporation dynamics. We experimentally investigate two different flows with opposite directions: downward sedimentation flows by gravity (\documentclass[12pt]{minimal}
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\begin{document}$$\ll$$\end{document}≪ 1, evaporation-driven upward flows overwhelm sedimentation-driven downward flows, resulting in accentuated particle movement towards the top ring, which seems to defy gravitational intervention. We suggest a possible explanation for the flow speed dependence of final deposits in evaporating colloidal droplets. This study offers a framework to understand the intervention of inclination to the formation of final deposits and how to overcome the deposit pattern radial asymmetry, achieving symmetric deposit widths from inclined colloidal droplets.
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Affiliation(s)
- Jin Young Kim
- Research Center for Advanced Materials Technology, Sungkyunkwan University, Suwon, 16419, South Korea.,Department of Materials, ETH Zürich, 8093, Zurich, Switzerland
| | - Marta Gonçalves
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 16419, South Korea
| | - Narina Jung
- Research Center for Advanced Materials Technology, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Hyoungsoo Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea.
| | - Byung Mook Weon
- Research Center for Advanced Materials Technology, Sungkyunkwan University, Suwon, 16419, South Korea. .,SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 16419, South Korea. .,School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, 16419, South Korea.
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12
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Winhard BF, Haugg S, Blick R, Schneider GA, Furlan KP. Direct writing of colloidal suspensions onto inclined surfaces: Optimizing dispense volume for homogeneous structures. J Colloid Interface Sci 2021; 597:137-148. [PMID: 33872874 DOI: 10.1016/j.jcis.2021.03.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 01/27/2023]
Abstract
HYPOTHESIS A process to fabricate structures on inclined substrates has the potential to yield novel applications for colloidal-based structures. However, for conventional techniques, besides the coffee ring effect (CRE), anisotropic particle deposition along the inclination direction (IE) is expected to occur. We hypothesize that both effects can be inhibited by reducing the dispense volume during printing by direct writing. EXPERIMENTS We combined an additive manufacturing technique, namely direct writing, with colloidal assembly (AMCA) for an automated and localized drop-cast of polystyrene and silica suspensions onto inclined surfaces. Herein, we investigated the influence of the substrate tilting angle and the dispense volume on the printing of colloids and the resulting structures' morphology. FINDINGS The results demonstrate that a reduction in the dispense volume hinders the CRE and IE for both particles' systems, even though the evaporation mode is different. For polystyrene, the droplets evaporated solely in stick-mode, enabling a "surface capturing effect", while for silica, droplets evaporated in mixed stick-slip mode and a "confinement effect" was observed, which improved uniformity of the deposition. These findings were used to generate a model of the critical droplet radius needed to print homogeneous colloidal-based structures onto inclined substrates.
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Affiliation(s)
- Benedikt F Winhard
- Hamburg University of Technology, Institute of Advanced Ceramics, Denickestraße 15, 21073 Hamburg, Germany.
| | - Stefanie Haugg
- Center for Hybrid Nanostructures, Universität Hamburg, Luruper Chaussee 149, 22607 Hamburg, Germany.
| | - Robert Blick
- Center for Hybrid Nanostructures, Universität Hamburg, Luruper Chaussee 149, 22607 Hamburg, Germany.
| | - Gerold A Schneider
- Hamburg University of Technology, Institute of Advanced Ceramics, Denickestraße 15, 21073 Hamburg, Germany.
| | - Kaline P Furlan
- Hamburg University of Technology, Institute of Advanced Ceramics, Denickestraße 15, 21073 Hamburg, Germany; Center for Hybrid Nanostructures, Universität Hamburg, Luruper Chaussee 149, 22607 Hamburg, Germany.
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13
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Kumar PL, Thampi SP, Basavaraj MG. Particle size and substrate wettability dependent patterns in dried pendant drops. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:024003. [PMID: 33055378 DOI: 10.1088/1361-648x/abb64e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The particle laden sessile drops when dried on solid surfaces under certain conditions leave a deposit pattern wherein all the particles are confined to a narrow region close to the edge of the deposit. Such patterns which often form when coffee drops dry are referred to as the coffee ring patterns or the coffee stains. Recent research points to the formation of intriguing patterns when colloidal particle laden drops are dried in configurations other than sessile mode. In this article, the combined effect of particle size and wettability of the substrate on the patterns formed by drying drops in sessile and pendant configurations is investigated via experiments. Our results demonstrate a transition from coffee ring to central dome-like deposit morphology with decrease in wettability of the substrates when drops containing 3 μm diameter particles are dried in pendent mode. A similar transition in the deposit morphology is observed with increase in the diameter of the particles in pendant drops dried on substrates of near neutral wettability (θ = 86 ± 3°). The influence of particles size, substrate wettability and drop configuration on the kinetics of deposition of particles at the three phase contact line will also be discussed. We compare our experimental observations with particle based simulations wherein the dried patterns are generated by accounting for three particle transport modes, namely, advective particle transport resulting from capillary flow, gravity driven settling of particles and particle capture by descending interface.
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Affiliation(s)
- P Logesh Kumar
- Polymer Engineering and Colloid Science Laboratory, Department of Chemical Engineering, Indian Institute of Technology Madras, 600036, Chennai, India
| | - Sumesh P Thampi
- Polymer Engineering and Colloid Science Laboratory, Department of Chemical Engineering, Indian Institute of Technology Madras, 600036, Chennai, India
| | - Madivala G Basavaraj
- Polymer Engineering and Colloid Science Laboratory, Department of Chemical Engineering, Indian Institute of Technology Madras, 600036, Chennai, India
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