Facile tuning of the mechanical properties of a biocompatible soft material

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  • Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir Prelog Weg 1, Zürich, 8093, Switzerland. d.vigolo@bham.ac.uk.
  • Laboratory for Surface Science and Technology, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093, Zürich, Switzerland.
  • Institute for Chemical and Bioengineering; Department of Chemistry and Applied Biosciences; ETH Zurich; Vladimir Prelog Weg 1 Zürich 8093 Switzerland


Herein, we introduce a method to locally modify the mechanical properties of a soft, biocompatible material through the exploitation of the effects induced by the presence of a local temperature gradient. In our hypotheses, this induces a concentration gradient in an aqueous sodium alginate solution containing calcium carbonate particles confined within a microfluidic channel. The concentration gradient is then fixed by forming a stable calcium alginate hydrogel. The process responsible for the hydrogel formation is initiated by diffusing an acidic oil solution through a permeable membrane in a 2-layer microfluidic device, thus reducing the pH and freeing calcium ions. We characterize the gradient of mechanical properties using atomic force microscopy nanoindentation measurements for a variety of material compositions and thermal conditions. Significantly, our novel approach enables the creation of steep gradients in mechanical properties (typically between 10-100 kPa/mm) on small scales, which will be of significant use in a range of tissue engineering and cell mechanosensing studies.


Original languageEnglish
Article number7125
Number of pages7
JournalScientific Reports
Issue number1
Publication statusPublished - 9 May 2019

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