text: The first OFM sampling probe to be used as an alternative to microdialysis was described in an Austrian patent application filed by Falko Skrabal in 1987, where OFM was described as a device, which can be implanted into the tissue of living organisms. In 1992, a US patent was filed claiming a device for determining at least one medical variable in the tissue of living organisms. In a later patent by Helmut Masoner, Falko Skrabal and Helmut List a linear type of the sampling probe with macroscopic circular holes was also disclosed. Alternative and current OFM versions for dermal and adipose tissue application were developed by [https://www.joanneum.at/en/health Joanneum Research], and were patented by Manfred Bodenlenz et al. Alternative materials featuring low absorption were used to enable manufacturing of probes with diameters of 0.55 mm and exchange areas of 15 mm in length. For cerebral application, special OFM probes were patented by Birngruber et al. Additionally, a patent was filed to manage the fluid handling of the ISF by using a portable peristaltic pump with a flow range of 0.1 to 10 µL/min that enables operation of up to three probes per pump.