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Updated: Jun 4, 2025
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Published on: February 1, 2016
Preservation of wetting ridges using field-induced plasticity of magnetoactive elastomers
Raphael Kriegl1, Lars Krenkel2, Mikhail Shamonin1
1East Bavarian Centre for Intelligent Materials (EBACIM), Ostbayerische Technische Hochschule Regensburg, Seybothstr. 2, Regensburg, 93053, Germany.
Hypothesis:
The presence of a wetting ridge is crucial for many wetting phenomena on soft substrates. Conventional experimental observations of a wetting ridge require permanent presence of a droplet. The magnetic field-induced plasticity effect (FIPE) of soft magnetoative elastomers (MAEs) allows one to overcome this limitation. Depositing a droplet onto an MAE surface and applying a magnetic field fixes the wetting ridge in place due to the FIPE. The droplet can be removed to investigate the ridge with ease using conventional optical methods.
Experiments:
The wetting ridge is observed on MAEs with different shear moduli and different material thicknesses by confocal laser scanning microscopy (LSM). The preservation quality of the ridge is analyzed for several values of magnetic field from 10mT to 270mT. To verify the plausibilty of results obtained, the measured shape is compared to a theoretical model by Style & Dufresne.
Findings:
Upon removal of the sessile droplet, the deformation remains embossed onto the MAE surface as long as the magnetic field remains applied. The height of the ridge peak on soft samples (effective shear modulus G<10kPa) is close to the theoretical prediction for a magnetic flux density of 50mT. The magnitude of the external magnetic field magnifies the height of the wetting ridge.
