The present invention relates to a method of producing a FinFET sensor device comprising the steps of: providing a silicon substrate; etching the silicon substrate to produce at least one upwardly extending Fin structure externally protruding from a surface of the silicon substrate; depositing a spacer layer on the at least one Fin structure; anisotropically etching a section of the spacer layer to expose the underlying silicon; isotropic etching of the exposed silicon surrounding the at least one Fin structure; and carrying out oxidation of the silicon surrounding the at least one Fin structure to produce a Fin structure of silicon inside the at least one Fin structure. The present invention also relates to FinFET sensor devices produced by the above method.