Issue 36, 2022, Issue in Progress

Surface acoustic wave-based generation and transfer of droplets onto wettable substrates

Abstract

Fluid manipulation using surface acoustic waves (SAW) has been utilized as a promising technique in the field of microfluidics due to its numerous advantages, over other active techniques, such as low power requirement, facile fabrication methods, and non-invasive nature. Even though SAW-based generation of micron-sized droplets through atomization has been studied, the role of substrate wettability on the characteristics of the transferred droplets has not been explored to date. Here, we study the generation and effective transfer of micron-sized droplets using SAW onto wettable substrates whose water contact angles vary from 5° to 145°. The characteristics of transferred droplets after impacting the wettable substrates are characterized in terms of the contact line diameter and polydispersity index. A theoretical model is formulated to predict the initial average size of the transferred droplets on the wettable substrates of different contact angles. The variation of polydispersity and number density with contact angle is explained by considering droplet coalescence and bouncing. The relevance of the technique in biological assays is demonstrated by transferring droplets of streptavidin protein samples onto a substrate.

Graphical abstract: Surface acoustic wave-based generation and transfer of droplets onto wettable substrates

Supplementary files

Article information

Article type
Paper
Submitted
02 Jul 2022
Accepted
09 Aug 2022
First published
17 Aug 2022
This article is Open Access
Creative Commons BY license

RSC Adv., 2022,12, 23400-23410

Surface acoustic wave-based generation and transfer of droplets onto wettable substrates

K. N. Nampoothiri, N. S. Satpathi and A. K. Sen, RSC Adv., 2022, 12, 23400 DOI: 10.1039/D2RA04089A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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