The device has a microinvasive or micro-sampling investigating system comprising a flexible metallic guide with an end containing a series of pits. The pits are directly coupled to a specific reactive group of a substrate, where the end is perforated. Another end of the metallic guide is used to maneuver the metallic guide and associated with an aspiration system. A removable protection system e.g. flexible catheter, is arranged at the former end of the metallic guide. An independent claim is also included for a method for detecting ex vivo of a substrate present in a tissue or organ.