Microfluidic analog of the four-roll mill

We describe a microfluidic trap, for analysis of fluids and suspensions, that simulates the function of a four-roll mill, a theological tool with adjustable flow type and rate. These flow characteristics were designed with the assistance of flow simulations and are measured here by micro-particle-image-velocimetry. This miniature device permits microscopic manipulations and measurements (e.g., of cells, particles, and drops) and it is capable of a range of flow types, including simple shear.