Sensing Local Stresses with Mechano-Responsive Polymer Structures

We utilize mechano-responsive polymer brushes as spatially resolving force sensors. By labelling with fluorophores, local mechanical deformation of the polymer can be translated into an optical signal that can be read out with confocal microscopy.
Recently, we these systems to resolve the stress distributions in the contact area of bioinspired microstructures. Compressive and tensile stresses could be read out from locally decreased and increased fluorescence intensity, respectively.
For the quantification of the stresses, the calibration with Soft Colloidal Probe AFM is possible. In earlier work, the sensitivity upon compression was determined to 10 kPa with a spatial resolution better than human skin (1 µm).

With polymer brush layers being limited to a two-dimensional, planar geometry, we aim for transferring the mechano-response principle to polymer networks as an extension to the third dimension.
Currently, we focus on designing mechano-responsive microparticles. In need of mechanically defined properties, we utilize droplet microfluidics for controlling the homogeneity of a polymer network in spherical hydrogel microparticles.