Dynamically controlled deposition of colloidal nanoparticle suspension in evaporating drops using laser radiation.
Dynamic control of the distribution of polystyrene suspended nanoparticles in evaporating droplets is investigated using a 2.9 μm high power laser. Under laser radiation a droplet is locally heated and fluid flows are induced that overcome the capillary flow, and thus a reversal of the coffee-stain effect is observed. Suspension particles are accumulated in a localised area, one order of magnitude smaller than the original droplet size. By scanning the laser beam over the droplet, particles can be deposited in an arbitrary pattern. This finding raises the possibility for direct laser writing of suspended particles through a liquid layer. Furthermore, a highly uniform coating is possible by manipulating the laser beam diameter and exposure time. The effect is expected to be universally applicable to aqueous solutions independent of solutes (either particles or molecules) and deposited substrates.
Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. d.ta@hw.ac.uk.
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Ta
Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. d.ta@hw.ac.uk.
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Carter
Warwick Mathematics Institute, Zeeman Building, University of Warwick, Coventry CV4 7AL, UK and Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
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Esenturk
Warwick Mathematics Institute, Zeeman Building, University of Warwick, Coventry CV4 7AL, UK and Centre for Complexity Science, Zeeman Building, University of Warwick, Coventry CV4 7AL, UK.
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Connaughton
Additive Manufacturing Research Group, Loughborough University, Leicestershire, LE11 3TU, UK.
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TJ
Wasley
Additive Manufacturing Research Group, Loughborough University, Leicestershire, LE11 3TU, UK.
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J
Li
Additive Manufacturing Research Group, Loughborough University, Leicestershire, LE11 3TU, UK.
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RW
Kay
Laboratory of Applied Inkjet Printing, Department of Mechanical Engineering, University of Sheffield, Sheffield, S1 4BJ, UK and Department of Mechanical Engineering, The University of Auckland, Auckland 1142, New Zealand.
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J
Stringer
Laboratory of Applied Inkjet Printing, Department of Mechanical Engineering, University of Sheffield, Sheffield, S1 4BJ, UK.
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PJ
Smith
Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. d.ta@hw.ac.uk.
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Shephard