Compression and reswelling of microgel particles after an osmotic shock

We use dedicated microuidic devices to expose soft hydrogel particles to a rapid change in the
externally applied osmotic pressure and observe a surprising, non-monotonic response: After an
initial rapid compression, the particle slowly reswells to approximately its original size. We the-
oretically account for this behavior, enabling us to extract important material properties from a
single microuidic experiment, including the compressive modulus, the gel permeability, and the
diffusivity of the osmolyte inside the gel. We expect our approach to be relevant to applications
such as controlled release, chromatography, and responsive materials.