Flow Monitoring in Microdialysis Systems for Continuous Sampling

Continuous in vivo sampling of medically relevant substances using the microdialysis method requires the most exact possible knowledge about the involved perfusate flow. As this flow is typically in the range of few microliters per hour a flow sensor with a resolution of less than 1 microliter per hour is required. This paper will present such a sensor based on a calorimetrical measurement. The described principle of operation allows not only the flow measurement itself but also an additional detection of the involved fluids thermal characteristics, allowing the compensation of important interferents in this and similar micro fluidic applications, e.g. gas enclosures.