Swelling-induced Instability of Substrate-attached Hydrogel Lines
نویسندگان
چکیده
Microand nano-scale hydrogel lines can be fabricated on substrates by top-down approaches such as lithography and micro/nano-imprint. When in contact with a solvent, the hydrogel lines swell under the constraint of the substrate, often resulting in distorted shapes or instability patterns. In this paper, using a nonlinear finite element method, the effects of material and geometry on swell-induced instability of substrate-attached hydrogel lines are studied. Firstly, with a two-dimensional plane-strain model, we show that crease-like surface instability occurs in hydrogel lines with the width-to-height aspect ratio greater than a critical value. Next, for relative low aspect ratios, we show that a global buckling instability occurs. In both cases, the critical conditions depend on the material parameters that characterize the elastic stiffness of the polymer network and the chemical interaction between solvent and polymer in the hydrogel.
منابع مشابه
Swell-induced instability of substrate-attached hydrogel lines
Micro and nano-scale hydrogel lines can be fabricated on substrates by top-down approaches such as lithography and micro/nano-imprint. When in contact with a solvent, the hydrogel lines swell under the constraint of the substrate, often resulting in distorted shapes or instability patterns. In this paper, using a nonlinear finite element method, the effects of material and geometry on swell ind...
متن کاملEffect of surface tension on swell-induced surface instability of substrate-confined hydrogel layers†
Swell-induced surface instability has been observed experimentally in rubbers and gels. Here we present a theoretical model that predicts the critical condition along with a characteristic wavelength for swellinduced surface instability in substrate-confined hydrogel layers. The effect of surface tension is found to be critical in suppressing short-wavelength modes of instability, while the sub...
متن کاملSwell-induced surface instability of confined hydrogel layers on substrates
In response to external stimuli, polymeric hydrogels can change volume and shape dramatically. Experimental studies have observed a variety of instability patterns of hydrogels, due to swelling or shrinking, many of which have not been well understood. The present paper considers swell-induced surface instability of a hydrogel layer on a rigid substrate. Based on a recently developed theoretica...
متن کاملCoupled instabilities of surface crease and bulk bending during fast free swelling of hydrogels.
Most studies on hydrogel swelling instability have been focused on a constrained boundary condition. In this paper, we studied the mechanical instability of a piece of disc-shaped hydrogel during free swelling. The fast swelling of the gel induces two swelling mismatches; a surface-inner layer mismatch and an annulus-disc mismatch, which lead to the formation of a surface crease pattern and a s...
متن کاملA Variational Approach and Finite Element Implementation for Swelling of Polymeric Hydrogels Under Geometric Constraints
A hydrogel consists of a cross-linked polymer network and solvent molecules. Depending on its chemical and mechanical environment, the polymer network may undergo enormous volume change. The present work develops a general formulation based on a variational approach, which leads to a set of governing equations coupling mechanical and chemical equilibrium conditions along with proper boundary co...
متن کامل