Direct force measurement of microscopic droplets pulled along soft surfaces

Hamza K. Khattak, Stefan Karpitschka, Jacco H. Snoeijer, Kari Dalnoki-Veress*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)
43 Downloads (Pure)


When a droplet is placed on a soft surface, surface tension deforms the substrate, creating a capillary ridge. We study how the motion of the ridge dissipates energy in microscopic droplets. Using a micropipette based method, we are able to simultaneously image and measure forces on a microscopic droplet moving at a constant speed along a soft film supported on a rigid substrate. Changing the thickness of the thin film tunes the effective stiffness of the substrate. Thus we can control the ridge size without altering the surface chemistry. We find that the dissipation depends strongly on the film thickness, decreasing monotonically as effective stiffness increases. This monotonic trend is beyond the realm of small deformation theory, but can be explained with a simple scaling analysis.

Original languageEnglish
Article number4436
Pages (from-to)1-6
Number of pages6
JournalNature communications
Issue number1
Early online date30 Jul 2022
Publication statusPublished - Dec 2022


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