Methods of diagnosing and/or monitoring tuberculosis (TB) in a subject by analyzing a test sample comprising at least one volatile organic compound (VOC) or semi-volatile organic compound (SVOC) emitted or excreted from the skin of the subject. The test sample can be analyzed by a sensing unit comprising nanomaterials- and/or polymer-based sensors. Further provided is a skin-mountable device comprising a fixing unit and said sensing unit. Also discloses a method of diagnosing and/or monitoring tuberculosis, comprising analyzing specific skin-emitted VOCs or SVOCs, which are indicative of tuberculosis in a subject.