Abstract: The present invention provides a dermal patch for selectively retaining one or more analyte(s) from a body of a subject comprising: a membrane layer (101) for retaining one or more analyte(s) from a body of a subject, with a first and a second side, wherein the first side is adapted to be in fluid communication with the skin of the subject; optionally holding means for securing the membrane layer in place; an adhesive layer (104); and a backing layer; wherein between the backing layer and the membrane layer (101) there is an expandable layer (103) for applying pressure to the membrane layer.