OFM uses probes with macroscopic openings to exchange substances in a liquid pathway that is based on convection rather than diffusion so that the exchange can occur non-selectively in either direction.
The direct liquid pathway between the probe’s perfusate and the surrounding interstitial fluid (ISF) provides a diluted but otherwise unchanged ISF sample, since no dialysis or filtering occurs. OFM provides unfiltered, merely diluted interstitial fluid from the investigated target tissues (skin, adipose, brain tissue). Endogenous and exogenous substances present in the interstitial fluid of targeted tissues can thus be quantified without the risk of investigating an altered sample.
OFM probes are perfused with a physiological solution (perfusate) which equilibrates with the interstitial fluid (ISF) of the surrounding tissue. Operating flow rates range from 0.1 to 10 μL/min. OFM allows unrestricted exchange of compounds Via the open exchange are of the probe. This exchange of compounds between the probe’s perfusate and the surrounding ISF is driven by convection and diffusion, and occurs non-selectively in either direction.
The concentric OFM probe
The direct liquid pathway between the probe’s perfusate and the surrounding fluid results in collection of ISF samples. These samples can be collected frequently and are then subjected to bioanalytical analysis to enable monitoring of substance concentrations with temporal resolution during the whole sampling period.The concentric OFM probe (Figure 2) works according to the same principle. The perfusate is pumped to the tip of the OFM probe through the inner, thin tubing and exits behind the Open Exchange Area. There it mixes with exogenous substances present in the ISF and is withdrawn through the outer, thick tubing.
Study materials
Complementary methods
Study materials