The present invention relates to a hydrophobic valve for liquids having an appreciable surface tension comprising magnetic particles, said device comprising at least two planar solid substrates with a functionalized surface each, wherein at least a first solid substrate has a patterned surface comprising at least two hydrophilic areas separated from one another by at least one hydrophobic area, wherein the said two planar substrates are disposed with a distance to one another in a sandwiched, parallel fashion, in such way that said functionalized surfaces are facing one another, said valve further comprising a magnetic actuator.