In-situ Sub-micrometer Surface Flow Velocity Measurment

We have measured the flow velocity at a sub-micrometer distance from a flow channel wall by tracing the refractive index boundary of two consecutively flowed liquids. Using the surface plasmon resonance method to measure the surface proximity refractive index, we were able to measure the velocity without using additional tracer materials. This velocimetry can be performed while simultaneously measuring the reaction rate of surface immobilized biologically functioning molecules. Combining these two measurements enabled us to improve the fidelity of adsorption measurements of real samples undertaken using a capillary pumping biosensor by determining the flow velocity for each sample injection.