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DY: Fachverband Dynamik und Statistische Physik
DY 14: Microfluidics and Droplets - organized by Uwe Thiele (Münster)
DY 14.6: Talk
Monday, March 22, 2021, 17:40–18:00, DYa
Characterizing the speed, size and shape of droplets during their flight from an ultrasonic spray coater — •Pieter Verding1,2, Wim Deferme1,2, and Werner Steffen3 — 1Hasselt University Institute for Materials Research, Diepenbeek, Belgium — 2IMEC, Diepenbeek,Belgium — 3Max-Planck-Institut for Polymer research, Mainz, Germany
Ultrasonic spray coating - USSC is a technology offering numerous possibilities, such as depositing ultrathin homogeneous layers up to 20 nm on large scale. However, its application is limited due to the many process parameters which have a large impact on the quality of the coating. For this reason, measuring the droplet size, speed and concentration during the flight from the ultrasonically generated droplet to the substrate, gives insight in how to tune these parameters. Because thousands of droplets are created at the same time, measuring the properties of the droplets during flight is a complicated task. Three different measurement techniques have been developed in and around an USSC setup. Dynamic Light Scattering (DLS) shows, after Fourier transformation, shifted peaks, representing the speed of the droplets. By applying Turbidimetry, it is possible to determine the size of the droplets. Droplets size and speed could be measured and gave comparable results as measured with a High Speed Camera (HSC). Furthermore, it was shown that the size and velocity of the droplets depend on the process parameters. It is therefore concluded from this work that a combination of DLS and Turbidimetry is a valuable alternative to measure droplets during their flight from an USSC.