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  • Open Access

Asymptotic description of confined hydrogel swelling

Ellen M. Jolley*, Daniel J. Booth, and Thomas D. Montenegro-Johnson

  • *Contact author: ellen.jolley@warwick.ac.uk
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Phys. Rev. Fluids 11, 053102 – Published 14 May, 2026

DOI: https://doi.org/10.1103/rvl1-1c4y

Abstract

Hydrogels are soft, poroelastic solids, comprising hydrophilic polymer scaffold surrounded by adsorbed water that is free to move through the pore spaces. Hydrogels are typically biocompatible, and are therefore used in a wide variety of medical contexts. For instance, they are used to make soft contact lenses, and have potential as advanced wound dressings, targeted drug delivery devices, and deployable intestinal stents. In all these applications, the hydrogel tends to be confined by or adhered to its surroundings, and while hydrogel dynamics has received increasing mathematical attention recently, most studies have focused on free swelling. In this paper, we mathematically analyze the swelling and deswelling behavior of a hydrogel confined between two plates, in both the case where the hydrogel can slip parallel to the wall and the case where it cannot. In the slip case, we numerically solve for a full nonlinear solution based on uniaxial deformation. In the adhered case, focusing on small deformation, we find that the gel may swell either completely or incompletely (i.e., the water only penetrates partially though the gel). We give a leading-order closed-form solution for the evolution of the porosity, and thus the force on the two plates, in both cases. The partial swelling may greatly impact the efficacy of hydrogels as actuators for deployable medical devices, so may need to be a consideration in design.

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Phys. Rev. Fluids 11, 053102– Published 14 May, 2026
  • Received 6 January 2026
  • Accepted 17 April 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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