Evaporation of picoliter droplets on surfaces with a range of wettabilities and thermal conductivities

Abstract

Publisher's copyright statement:Reprinted with permission from the American Physical Society: Talbot, E.L., Berson, A., Brown, P.S. and Bain, C.D. Physical Review E, 85, 061604, 2012. c 2012 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The evaporation of picoliter water and ethanol droplets generated by drop-on-demand inkjet printing was investigated on substrates with apparent contact angles between 10• and 135• and thermal conductivities between 0.25 and 149 W m −1 K −1 . Drying times were calculated from a diffusion-limited model for droplets with both pinned and moving contact lines as a function of droplet diameter and apparent contact angle. Droplets with a moving contact line take longer to dry on hydrophilic substrates than pinned droplets. The difference in drying times between evaporative modes vanishes at large apparent contact angles. Hence similar drying times are obtained for both modes on hydrophobic substrates. The predicted drying times for glass and silicon substrates were in good quantitative agreement with experimental data, suggesting that thermal effects are negligible for substrates of these base materials. However, on a PTFE substrate which has a lower thermal conductivity more relevant to inkjet printing, evaporative cooling reduces the evaporation rate causing drying times to be underpredicted by isothermal models.

Rheological Control of the Coffee Stain Effect for Inkjet Printing of Ceramics

“…Kuerten and Siregar stated that the drying time for inkjet droplets is usually in the range of a few seconds. This is confirmed by recent experiments of Talbot et al . Probably even more interesting than the overall drying time is the time span for the IPA evaporation in our case.…”

On the lifetimes of evaporating droplets

“…In many situations the evaporation of droplets is well described by the diffusionlimited model, in which diffusion of vapour from the droplet into the surrounding atmosphere is the rate-limiting mechanism (see, for example, Picknett & Bexon (1977), Deegan et al (1997), Hu & Larson (2002) Talbot et al (2012) and Dash & Garimella (2013)). …”

Evaporation of Droplets of Surfactant Solutions

“…Evaporation of liquid droplets in a gas volume has implications in different areas: spray drying and production of fine powders [1][2][3], spray cooling [4][5][6], fuel preparation [7-10], air humidifying [11], heat exchangers [12], drying in evaporation chambers of air conditioning systems [11,12], fire extinguishing [13,14], fuel spray auto ignition (Diesel) [15], solid surface templates from evaporation of nanofluid drops (coffee-ring effect) [16], spraying of pesticides [1][2][3], painting, coating and inkjet printing [17], printed MEMS devices, micro lens manufacturing, spotting of DNA microarray data [3,[18][19]. Because of such wide range of industrial applications this phenomenon has been under investigation for many years, both for pure fluids and for complex fluids.…”