A multi-axis confocal rheoscope for studying shear flow of structured fluids

We present a new design for a confocal rheoscope that enables uniform uniaxial or biaxial shear. The design consists of two precisely-positioned parallel plates with a gap that can be adjusted down to 2$\pm$0.1 \mu m, allowing for the exploration of confinement effects. By using our shear cell in conjunction with a biaxial force measurement device and a high-speed confocal microscope, we are able to measure the real-time biaxial stress while simultaneously imaging the material 3D structure. We illustrate the importance of the instrument capabilities by discussing the applications of this instrument in current and future research topics in colloidal suspensions.