A SHEAR DEVICE FOR THE MICROSCOPIC OBSERVATIONS OF SUSPENSIONS AND EMULSIONS

We describe a shear device designed to allow the visualization of suspensions or emulsions under an optical microscope. The optical axis of the microscope is perpendicular to the plane of shear. The detailed flow profile is determined by numerical simulation with two different aspect ratios of the flow cell. We use this shear device to investigate the structure of dilute suspensions of colloidal magnetic particles submitted to a magnetic field and to a flow.